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Six Tough Questions About Climate Change

Whenever the focus is on climate change, as it is right now at the  Paris climate conference , tough questions are asked concerning the costs of cutting carbon emissions, the feasibility of transitioning to renewable energy, and whether it’s already too late to do anything about climate change. We posed these questions to Laura Segafredo , manager for the Deep Decarbonization Pathways Project . The decarbonization project comprises energy research teams from 16 of the world’s biggest greenhouse gas emitting countries that are developing concrete strategies to reduce emissions in their countries. The Deep Decarbonization Pathways Project is an initiative of the Sustainable Development Solutions Network .

• Will the actions we take today be enough to forestall the direct impacts of climate change? Or is it too little too late?

There is still time and room for limiting climate change within the 2˚C limit that scientists consider relatively safe, and that countries endorsed in Copenhagen and Cancun. But clearly the window is closing quickly. I think that the most important message is that we need to start really, really soon, putting the world on a trajectory of stabilizing and reducing emissions. The temperature change has a direct relationship with the cumulative amount of emissions that are in the atmosphere, so the more we keep emitting at the pace that we are emitting today, the more steeply we will have to go on a downward trajectory and the more expensive it will be.

Today we are already experiencing an average change in global temperature of .8˚. With the cumulative amount of emissions that we are going to emit into the atmosphere over the next years, we will easily reach 1.5˚ without even trying to change that trajectory.

Two degrees might still be doable, but it requires significant political will and fast action. And even 2˚ is a significant amount of warming for the planet, and will have consequences in terms of sea level rise, ecosystem changes, possible extinctions of species, displacements of people, diseases, agriculture productivity changes, health related effects and more. But if we can contain global warming within those 2˚, we can manage those effects. I think that’s really the message of the Intergovernmental Panel on Climate Change reports—that’s why the 2˚ limit was chosen, in a sense. It’s a level of warming where we can manage the risks and the consequences. Anything beyond that would be much, much worse.

• Will taking action make our lives better or safer, or will it only make a difference to future generations?

It will make our lives better and safer for sure. For example, let’s think about what it means to replace a coal power plant with a cleaner form of energy like wind or solar. People that live around the coal power plant are going to have a lot less air pollution, which means less asthma for children, and less time wasted because of chronic or acute diseases. In developing countries, you’re talking about potentially millions of lives saved by replacing dirty fossil fuel based power generation with clean energy.

It will also have important consequences for agricultural productivity. There’s a big risk that with the concentration of carbon and other gases in the atmosphere,   agricultural yields will be reduced, so preventing that means more food for everyone.

And then think about cities. If you didn’t have all that pollution from cars, we could live in cities that are less noisy, where the air’s much better, and have potentially better transportation. We could live in better buildings where appliances are more efficient. And investing in energy efficiency would basically leave more money in our pockets. So there are a lot of benefits that we can reap almost immediately, and that’s without even considering the biggest benefit—leaving a planet in decent condition for future generations.

• How will measures to cut carbon emissions affect my life in terms of cost?

To build a climate resilient economy, we need to incorporate the three pillars of energy system transformation that we focus on in all the deep decarbonization pathways. Number one is improving energy efficiency in every part of the economy—buildings, what we use inside buildings, appliances, industrial processes, cars…everything you can think of can perform the same service, but using less energy. What that means is that you will have a slight increase in the price in the form of a small investment up front, like insulating your windows or buying a more efficient car, but you will end up saving a lot more money over the life of the equipment in terms of decreased energy costs.

The second pillar is making electricity, the power sector, carbon-free by replacing dirty power generation with clean power sources. That’s clearly going to cost a little money, but those costs are coming down so quickly. In fact there are already a lot of clean technologies that are at cost parity with fossil fuels— for example, onshore wind is already as competitive as gas—and those costs are only coming down in the future. We can also expect that there are going to be newer technologies. But in any event, the fact that we’re going to use less power because of the first pillar should actually make it a wash in terms of cost.

The Australian deep decarbonization teams have estimated that even with the increased costs of cleaner cars, and more efficient equipment for the home, etc., when the power system transitions to where it’s zero carbon, you still have savings on your energy bills compared to the previous situation.

The third pillar that we think about are clean fuels, essentially zero-carbon fuels. So we either need to electrify everything— like cars and heating, once the power sector is free of carbon—or have low-carbon fuels to power things that cannot be electrified, such as airplanes or big trucks. But once you have efficiency, these types of equipment are also more efficient, and you should be spending less money on energy.

Saving money depends on the three pillars together, thinking about all this as a whole system.

• Given that renewable sources provide only a small percentage of our energy and that nuclear power is so expensive, what can we realistically do to get off fossil fuels as soon as possible?

There are a lot of studies that have been done for the U.S. and for Europe that show that it’s very realistic to think of a power sector that is almost entirely powered by renewables by 2050 or so. It’s actually feasible—and this considers all the issues with intermittency, dealing with the networks, and whatever else represents a technological barrier—that’s all included in these studies. There’s also the assumption that energy storage, like batteries, will be cheaper in the future.

That is the future, but 2050 is not that far away. 35 years for an energy transition is not a long time. It’s important that this transition start now with the right policy incentives in place. We need to make sure that cars are more efficient, that buildings are more efficient, that cities are built with more public transit so less fossil fuels are needed to transport people from one place to another.

I don’t want people to think that because we’re looking at 2050, that means that we can wait—in order to be almost carbon free by 2050, or close to that target, we need to act fast and start now.

• Will the remedies to climate change be worse than the disease? Will it drive more people into poverty with higher costs?

I actually think the opposite is true. If we just let climate go the way we are doing today by continuing business as usual, that will drive many people into poverty. There’s a clear relationship between climate change and changing weather patterns, so more significant and frequent extreme weather events, including droughts, will affect the livelihoods of a large portion of the world population. Once you have droughts or significant weather events like extreme precipitation, you tend to see displacements of people, which create conflict, and conflict creates disease.

I think Syria is a good example of the world that we might be going towards if we don’t do anything about climate change. Syria is experiencing a once-in-a-century drought, and there’s a significant amount of desertification going on in those areas, so you’re looking at more and more arid areas. That affects agriculture, so people have moved from the countryside to the cities and that has created a lot of pressure on the cities. The conflict in Syria is very much related to the drought, and the drought can be ascribed to climate change.

And consider the ramifications of the Syrian crisis: the refugee crisis in Europe, terrorism, security concerns and 7 million-plus people displaced. I think that that’s the world that we’re going towards. And in a world like that, when you have to worry about people being safe and alive, you certainly cannot guarantee wealth and better well-being, or education and health.

• So finally, doing what needs to be done to combat climate change all comes down to political will?

The majority of the American public now believe that climate change is real, that it’s human induced and that we should do something about it.

But there’s seems to be a disconnect between what these numbers seem to indicate and what the political discourse is like… I can’t understand it, yet it seems to be the situation.

I’m a little concerned because other more immediate concerns like terrorism and safety always come first. Because the effects of climate change are going to be felt a little further away, people think that we can always put it off. The Department of Defense, its top-level people, have made the connection between climate change and conflict over the next few decades. That’s why I would argue that Syria is actually a really good example to remind us that if we are experiencing security issues today, it’s also because of environmental problems. We cannot ignore them.

The reality is that we need to do something about climate change fast—we don’t have time to fight this over the next 20 years. We have to agree on this soon and move forward and not waste another 10 years debating.

Read the Deep Decarbonization Pathways Project 2015 report . The full report will be released Dec. 2.

Laura Segafredo was a senior economist at the ClimateWorks Foundation, where she focused on best practice energy policies and their impact on emission trajectories. She was a lead author of the 2012 UNEP Emissions Gap Report and of the Green Growth in Practice Assessment Report. Before joining ClimateWorks, Segafredo was a research economist at Electricité de France in Paris.

She obtained her Ph.D. in energy studies and her BA in economics from the University of Padova (Italy), and her MSc in economics from the University of Toulouse (France).

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Many find low wages prohibits saving. Changing personal vehicles and heating systems costs. Will there be financial support for people on low wages?

The energy innovation and dividend bill has already been introduced in the house. It’s a carbon fee and dividend plan. The carbon fee rises every year and 100% of it goes back directly into the hands of the people by a check each month. This helps offset rising costs, especially for lower income folks.

81 cosponsors now Tell your rep in Congress to support this HR 763!

Results show that yields for all four crops grown at levels of carbon dioxide remaining at 2000 levels would experience severe declines in yield due to higher temperatures and drier conditions. But when grown at doubled carbon dioxide levels, all four crops fare better due to increased photosynthesis and crop water productivity, partially offsetting the impacts from those adverse climate changes. For wheat and soybean crops, in terms of yield the median negative impacts are fully compensated, and rice crops recoup up to 90 percent and maize up to 60 percent of their losses.

When is Russia, China, and Mexico going to work toward a better environment instead of the United States trying to do it all? They continue to pollute like they have for years. Who is going to stop the deforestation of the rain forest?

I’m curious if climate change has any effect on seismic activity. It seems with ice melting on the poles and increasing water dispersement and temp of that water, it might cause the plates to shift to compensate. Is there any evidence of this?

this isn’t because of doldrums or jet streams. the pattern keeps having the same action. we must save trees :3

How long do we have, before it’s too late?

Climate Change isn’t nearly as big of a deal as everyone makes it out to be. Meaning no disrespect to the author, but I really don’t see how this is something that we should be worrying about given that one human recycling their soda cans or getting their old phone refurbished rather than dumping it isn’t going to restore the polar ice caps or lower the temperature of the planet. And supposedly agriculture is the problem, but I point-blank refuse to give up my beef night, or bacon and eggs for breakfast on Saturdays. Also, nuclear power is supposed to be a solution, but the building of the power plants is going to add more greenhouse gases than the plant will take out. The whole planet needs a reality check. Earth isn’t going to explode because it’s slightly hotter than it used to be!

Thank you and I need in your help

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Global warming frequently asked questions

] Earth’s average surface temperature has risen by 1.8°F (1.0°C) since the late 1800s, an average rate of 0.13° F (0.07° C) per decade. Since 1981, the rate of warming has more than doubled to 0.32°F (0.18°C) per decade. The six warmest years in the 1880–2020 record have all occurred since 2014, while 19 of the 20 warmest years have occurred since 2001.  ] With significant reductions in the emissions of greenhouse gases, the annual global surface temperature rise this century could be limited to 3.6°F (2°C) or less. Without major reductions in these emissions, the increase in annual average global temperatures relative to preindustrial times could reach 9°F (5°C) or more by the end of this century. ] Learn more and .

] Thanks to natural climate variability, volcanic eruptions, and to a smaller extent, low solar activity, the rate of average global warming from 1998–2013 was slower than it had been over the two preceding decades. Such varations in the rate of warming from decade to decade are common. ] Meanwhile, excess heat continued to accumulate in the deeper layers of the ocean, contributing to marine heat waves and sea level rise. ] The slowdown in surface warming was only temporary, however, as the six warmest years in recorded history have all occurred after 2013. ] Learn more and

. and and . . ] Carbon dioxide, methane, nitrous oxide, ozone, and various chlorofluorocarbons are all human-emitted . Among these, carbon dioxide is of greatest concern to scientists because it exerts a larger overall warming influence than the .

At present, humans are putting an estimated 9.5 billion metric tons of carbon into the atmosphere each year by burning fossil fuels, and another 1.5 billion through deforestation and other land cover changes. Of this human-produced carbon, forests and other vegetation absorb around 3.2 billion metric tons per year, while the ocean absorbs about 2.5 billion metric tons per year. A net 5 billion metric tons of human-produced carbon remain in the atmosphere each year, raising the global average carbon dioxide concentrations by about 2.3 parts per million per year. Since 1750, humans have increased the abundance of carbon dioxide in the atmosphere by nearly 50 percent. ]  .

and ?

generally refers to the long-term increase in global average temperature as a result of human activity. Climate change is a much broader term that covers changes in multiple parts of the climate system, from temperature to precipitation to wind patterns. Climate change can be local, regional, or global, and it can have natural or human causes. Global warming is a type of climate change; however, not all climate change is global warming. .

] When different teams of climate scientists in different agencies (e.g., NOAA and NASA) and in other countries (e.g., the U.K.’s Hadley Centre) average these data together, they all find essentially the same result: Earth’s average surface temperature has risen by about 1.8°F (1.0°C) since 1880. ]

In addition to our surface station data, we have many different lines of evidence that Earth is warming ( ). Birds are migrating earlier, and their migration patterns are changing. and are moving north. Plants are blooming earlier in the spring. Mountain glaciers are melting and snow cover is declining in the Northern Hemisphere (Learn more and ). Greenland’s ice sheet—which holds about 8 percent of Earth’s fresh water—is melting at an accelerating rate ( ). Mean global sea level is rising ( ). Arctic sea ice is declining rapidly in both thickness and extent ( ).

We know this warming is largely caused by human activities because the key role that carbon dioxide plays in maintaining Earth’s natural greenhouse effect has been understood since the mid-1800s. Unless it is offset by some equally large cooling influence, more atmospheric carbon dioxide will lead to warmer surface temperatures. Since 1800, the amount of carbon dioxide in the atmosphere from about 280 parts per million to 410 ppm in 2019. We know from both its rapid increase and its isotopic “fingerprint” that the source of this new carbon dioxide is fossil fuels, and not natural sources like forest fires, volcanoes, or outgassing from the ocean.

Finally, no other known climate influences have changed enough to account for the observed warming trend. Taken together, these and other lines of evidence point squarely to human activities as the cause of recent global warming.

] In addition, fossil fuels are the only source of carbon consistent with the of the carbon present in today’s atmosphere. That analysis indicates it must be coming from terrestrial plant matter, and it must be very, very old. These and other lines of evidence leave no doubt that fossil fuels are the primary source of the carbon dioxide building up in Earth’s atmosphere.

] [ ] [ ] [ ]

This scientific consensus is clearly summarized in the climate assessment reports of the U.S. Global Change Research Program and the Intergovernmental Panel on Climate Change. ] [ ] [ ] NOAA scientists played lead roles in authoring and editing both sets of reports.

Additionally, the United States’ foremost science agencies and organizations have all recognized global warming as a human-caused problem that threatens human and natural systems and, therefore, should be addressed. These agencies and organizations include (but are not limited to) ; the ; the ; the ; the ; the ; the ; the ; the ; and the .

is the short-term atmospheric conditions at a given location on a specific day and time. is usually described as the long-term average weather at a given place, but it the range of weather conditions that are possible at a given place, including the types and historical frequency of extreme events that occur there. By analogy, if the outcome of any given at-bat is like the weather, then a baseball player’s career batting average is like the climate. There’s an old saying: “Climate is what you expect; weather is what you get.”

Another way to think about the difference between weather and climate is to say that a region’s climate is the background conditions that give rise to a location’s weather events. Because all weather occurs within Earth’s climate system, changes in the background state of the climate system can make different weather outcomes more or less likely to happen. For example, during the period from 1997-2018, the percentage area of the globe that experienced record-setting warm temperatures dwarfed the percentage area of the globe that experienced record-setting cold temperatures. ] This was a predictable set of weather outcomes due to global warming. .

conditions and climate is about conditions. Climate models are not trying, for example, to forecast the daytime high temperature in Chicago, IL, on August 15, 2035. They are trying to forecast the daytime high temperature for the of August over the entire of the 2030s. And while the exact weather conditions at a given location can change dramatically from hour to hour, the average changes much less from year to year or even decade to decade. The difference in time scale means that our ability to predict future climate doesn’t depend on our ability to predict next week’s weather.

Not only are weather models predicting different things than climate models, they require different kinds of starting information. Modelers call weather forecasting an problem because, at short time scales, the future atmospheric conditions depend mostly on the initial atmospheric conditions. The accuracy of your forecast for a given location depends heavily on how well you can describe these initial conditions, especially in the surrounding area.

In contrast, most modelers describe a climate projection as a problem because at long time scales (years to decades), future climate depends mostly on big-picture characteristics of the Earth system that don’t vary from day to day: the amount of land and ocean surface, the height and location of mountain ranges, the geometry of Earth’s orbit, and—crucially—the composition of the global atmosphere. These things define the boundaries of the climate system, the relatively narrow range of outcomes that are possible over long time frames.

These fundamental differences between weather models and climate models, in both what they are trying to predict and what those predictions depend on, mean that the quality of a weather forecast two weeks out isn’t a good test of how well we can predict the climate two decades out.

since the mid-1800s. The more greenhouse gases in the atmosphere, the more heat energy the atmosphere traps near the surface ( ), causing Earth’s surface temperature to rise.

The initial warming due to increasing carbon dioxide kicks off several feedback loops: more water vapor, which is a powerful greenhouse gas; permafrost thaw and decomposition, which releases more methane and carbon dioxide; loss of sea ice and snow, which reduces the amount of sunlight the Earth reflects; and outgassing of additional carbon dioxide from the ocean. Together, these feedback loops make the actual warming two or more times larger than it would be due to carbon dioxide increases alone. ]

] So in terms of total warming, water vapor is the most important greenhouse gas. But without the background warmth provided by carbon dioxide—which doesn’t condense and rain out of the atmosphere as water vapor does—the atmosphere would be too cold to support much water vapor, and the entire greenhouse effect would collapse. Models indicate Earth would likely freeze over everywhere but the equator. ] So in terms of making the greenhouse effect , carbon dioxide is the most important greenhouse gas.

As the most abundant of the non-condensing , carbon dioxide is the main control knob—the thermostat—of Earth’s greenhouse effect. ] Increases in atmospheric carbon dioxide from human activities are turning the thermostat up. As surface temperatures rise, more water evaporates, enhancing the initial warming. This water vapor feedback loop is powerful, at least doubling the warming provided by carbon dioxide alone. ] [ ] [ ] But water vapor can’t act on its own to cause climate change; it can only amplify a change caused by the non-condensing greenhouse gases or other climate influences, such as variations in incoming sunlight. That means that when it comes to causing global warming, carbon dioxide is without question the most important greenhouse gas.

]  ]  ]  ] It was partly through their attempts to understand previous ice ages that climate scientists came to understand the dominant role that carbon dioxide plays in Earth’s climate system, and the role it is playing in current global warming. Learn more and .

Over at least the past million years, have been triggered by in how much sunlight reaches the Northern Hemisphere in the summer, which are driven by small variations in the geometry of Earth’s orbit around the Sun. But these fluctuations in sunlight aren’t enough on their own to bring about full-blown ice ages and interglacials. They trigger several that amplify the original warming or cooling. During an interglacial,

These feedbacks until the Earth’s orbit goes through a phase during which the amount of Northern Hemisphere summer sunlight is minimized. Then these feedbacks operate in reverse, reinforcing the cooling trend.

During all the ice ages that have occurred over at least the past million years, these opposing branches of the carbon cycle have kept the atmospheric carbon dioxide level at or below 300 parts per million (ppm). ] , that level is close to 410 ppm. Not only is this the highest carbon dioxide has been during all of human civilization, it has reached these levels virtually instantaneously in geologic time frames. During ice age cycles of the past, a change this large would likely have taken thousands of years to occur.

This extremely rapid build-up of carbon dioxide is happening because humans are putting carbon dioxide into the atmosphere faster than natural sinks can remove it. By burning fossil fuels, we have essentially taken millions of years of carbon uptake by plants and returned it to the atmosphere in . ]

] to perhaps as much as 0.6 billion metric tons ], whereas human activities have been releasing more than 30 billion metric tons of carbon dioxide per year ] 

up to 0.1°C of the 1.0°C (1.8°F) of warming observed since the pre-industrial era. ] However, there has been no significant net change in the Sun’s energy output from the late 1970s to the present, which is when we have observed the most rapid global warming. .

A second reason that scientists have ruled out a significant role for the Sun in global warming is that if the Sun’s energy output had intensified, we would expect all layers of Earth’s atmosphere to have warmed. But we don’t see that. Rather, satellites and observations from weather balloons show warming in the lower atmosphere (troposphere) and cooling in the upper stratosphere (stratosphere)—which is exactly what we would expect to see as a result of increasing greenhouse gases trapping heat in the lower atmosphere. ] Scientists regard this piece of evidence as one of several “smoking guns” linking today’s global warming to human-emitted, heat-trapping gases.

are smaller than the warming influence of the heat-trapping gases humans put into the air. ]

Our greatest cooling influence comes from particulate pollution (aerosols) we produce. We put plumes of aerosols into the air from power plants and industrial smokestacks; smoke and gases from biomass burning; windblown dust from deforested areas, dried wetlands, and crop fields; exhaust from ships’ smokestacks; tailpipe emissions from cars, trucks, buses, and trains; etc. Aerosol particles absorb and reflect the sun’s rays, thereby reducing the amount of sunlight reaching Earth’s surface. They also interact with clouds, in many cases making them brighter and longer-lived, also reducing the amount of sunlight reaching the surface. .

Whereas aerosols linger in the atmosphere from days to a few weeks, heat-trapping gases that we add to the atmosphere linger from decades to centuries. Plus, when scientists discovered that our aerosol emissions were causing other undesired harmful side effects—such as acid rain and human respiratory diseases and deaths—we began to regulate and reduce their emission. Thus, the warming effect of our heat-trapping gases is ultimately winning out over the cooling influence of our particle pollution. .

makes it harder for shell-building marine life—including commercially and culturally valuable species such as coral, crabs, and oysters—to build and maintain their shells. ]

Because of its tremendous volume and high heat capacity, the ocean has absorbed more than 90 percent of all excess heat trapped in Earth's climate system by greenhouse gases. Currents mix much of that heat into deeper layers of the ocean, delaying the full impact of surface warming we would otherwise expect. However, the heating of deeper layers of the ocean still contributes to sea level rise, sea ice retreat, marine heatwaves, oxygen depletion and expanding dead zones, shifts in the ranges of several marine species, and accelerating loss of polar ice shelves. ]

and not necessarily in all seasons. It’s like your grades—if you get Bs and Cs in your first semester and in the next semester you get all As and Cs, your overall grade point average rises even though you didn’t improve in every class. Differences in exposure to sunlight, cloud cover, atmospheric circulation patterns, aerosol concentrations, atmospheric humidity, land surface cover, etc., all vary from place to place which, in turn, influence whether and how much a location is warming or cooling. Learn more , , , and .

Generally speaking, an extreme event is any event that ranks in the highest or lowest 5 percent or 10 percent of all historical observations of that type of event. The percentage threshold is arbitrary and is designated by a researcher to provide context on a given event or set of events.

Scientists sometimes describe extreme events in terms of their “sigmas” (or their “standard deviation”), which is a measure of how far removed an individual value is from the average of all observations in a data set. So, if a climate expert describes a heavy rain event as a “5-sigma event,” s/he is talking about rainfall so extreme that it was 5 standard deviations away from the average rainfall for that location—way out at the tail end of the range of all values that have ever been observed. .

Another way of characterizing an extreme event is by describing the probability of occurrence in a given span of time. Based on historical observations, experts to estimate the range of all possible events that we would eventually expect to observe if our data record was long enough. From this range of all possible values, they can pinpoint how frequently a particular value would be expected to recur within a given amount of time. For example, 100-year event means an event is so extreme that it has only a 1 percent chance (1 divided by 100) of happening in any given year. A thousand-year event has a 0.1 percent chance of happening in any single year (1 divided by 1,000). .

 by global warming. However, over the past decade, that climate change due to global warming has made many extreme events more likely, more intense, longer-lasting, or larger in scale than they would have been without it. For many of the events that have been studied, global warming has been identified as the primary driver of the event, not just a supporting player. And a number of recent studies have concluded that certain heat-related extreme events would not have been possible without human-caused global warming. Learn more   and  .

is the science of figuring out what caused a given extreme weather or climate event, and weighting the relative influence of global warming versus natural variability. The biggest collection of research dedicated to understanding the causes of extreme events is published annually in a special issue of the Bulletin of the American Meteorological Society. The most recent edition of the report, , was the eighth in the series. (The report covering a selection of events from 2019 is soon to be released). Together, these eight reports have documented 168 attribution studies, 73 percent of which identified a substantial link between an extreme event and human-caused climate change, whereas 27 percent did not. To learn more, go   and 

]

Today’s warming is occurring much more quickly than previous interglacial episodes. In transitions from an ice age to an interglacial, it took 5,000–10,000 years for the temperature to rise between 5 and 9° Fahrenheit (3–5° Celsius). Humans could witness the same amount of global warming within the next 80 years if we continue emitting heat-trapping gases at today’s rate. ]

Finally, if we cause our world to warm by 2.7°F (1.5°C) or more compared to the temperatures before the start of the Industrial Revolution, scientists warn that there will be harmful repercussions for human health, the economy, infrastructure, and agriculture and natural resources. ] The greater the warming above that threshold, the more widespread and severe the impacts are likely to be. Human and natural systems that cannot adapt quickly enough may be overwhelmed.

from year to year. In a geological context, a global-scale warming of 1.8°F (1°C) in less than 150 years is an unusually large temperature change in a relatively short span of time.

It's also important to recognize that Earth is not warming uniformly, nor is it expected to. Middle and high latitudes in general will warm more than the tropics, and land surface temperatures will rise more than ocean temperatures. Over the long term, land masses at the latitude of the United States are expected to warm much more than the global average.  ] If global warming continues at an increasing rate, in several decades the world is likely to be warmer than it's been for over a million years, with unpredictable consequences for humans and the natural resources we depend on.

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In terms of biodiversity, adaptable species with wide geographic ranges—such as white-tailed deer and feral hogs—are likely to continue to thrive. But those species that depend on particular habitats—polar and alpine species, coral reefs, coldwater fishes—are vulnerable, as are the communities that depend on them culturally and economically. ] According to the Fourth National Climate Assessment, “[S]pecies, including many iconic species, may disappear from regions where they have been prevalent or become extinct, altering some regions so much that their mix of plant and animal life will become almost unrecognizable.” ]

Food and forage production will decline in agricultural regions experiencing increased frequency and duration of drought. Even without drought, higher temperatures will increase evaporation of soil moisture, increasing crop stress and water demand—further stressing U.S. surface and groundwater supplies used for irrigation. And even with irrigation, many commodity crops are likely to experience declines in average yield as temperatures rise beyond their preferred heat tolerance range. Milder winters and shifts in precipitation are likely to increase the incidence of pests and diseases for crops and livestock, while extreme heat—especially nighttime heat—will reduce livestock productivity. Impacts will vary from region to region, depending on the extent of warming and the level of adaptation. ]

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] and the trend is likely to continue as many extreme events become more frequent and severe. The economic impacts of extreme events include not just the direct damages, but also the loss of productivity and interruption of essential services and supply chains that can reach deep into the national economy. ]

In many parts of the country, existing infrastructure—septic and stormwater systems, roads, bridges, the energy grid—was not designed to cope with current and future sea level and climate extremes, and current levels of investment aren’t enough to cover necessary repairs and upgrades. ]  ]

Beyond extreme events, human-caused climate change is likely to disrupt many sectors of the U.S. economy and the communities that depend on them, including commercial and recreational fisheries, tourism and recreation, and agriculture. ]  ]  ]

In the short term, farmers in some regions may benefit from the earlier onset of spring and from a longer warm season that is suitable for growing crops. Also, studies show that, up to a certain point, crops and other plants grow better in the presence of higher carbon dioxide levels and seem to be more drought-tolerant. ] But this benefit is a two-edged sword: weeds, many invasive plant species, and insect pests will also thrive in a warmer world. Water availability will be impacted in drier agricultural areas that need irrigation. At some point, the benefits to crops of increased carbon dioxide will likely be overwhelmed by the negative impacts of heat stress and drought.

In the long term, shipping commerce will benefit from the opening of the Northwest Passage for longer periods of the year due to the loss of Arctic sea ice. However, in the long run, if a "business as usual" approach to emitting heat-trapping gases is maintained at the present rate, or faster, then the negative costs and impacts of global warming are very likely to far outweigh the benefits over the course of this century, with increased potential for catastrophic impacts from more extreme events. ] In part, this is because any substantial change, whether warmer or colder, would challenge the societal infrastructure that has developed under the current climate.

]

If all human emissions of heat-trapping gases were to stop today, Earth’s temperature would continue to rise for a few decades as ocean currents bring excess heat stored in the deep ocean back to the surface. Once this excess heat radiated out to space, Earth’s temperature would stabilize. Experts think the additional warming from this “hidden” heat is unlikely to exceed 0.9° Fahrenheit (0.5°Celsius). ] With no further human influence, natural processes would begin to slowly remove the excess carbon dioxide from the atmosphere, and global temperatures would gradually begin to decline.

It’s true that without dramatic action in the next couple of decades, we are unlikely to keep global warming in this century below 2.7° Fahrenheit (1.5° Celsius) compared to pre-industrial temperatures—a threshold that experts say offers a lower risk of serious negative impacts. ] But the more we overshoot that threshold, the more serious and widespread the negative impacts will be, which means that it is never “too late” to take action.

it is likely many strategies working together will be needed. Generally speaking, here are some examples of mitigation strategies we can use to slow or stop the human-caused global warming ( ):

techniques.

Note that NOAA doesn’t advocate for or against particular climate policies. Instead, NOAA’s role is to provide data and scientific information about climate, including how it has changed and is likely to change in the future depending on different climate policies or actions society may or may not take. Learn more  and .

):

Note that NOAA doesn’t advocate for or against particular climate policies. Instead, NOAA’s role is to provide data and scientific information about climate, including how it has changed and is likely to change in the future depending on different climate policies or actions society may or may not take. Learn more  and .

NOAA is helping to improve the nation’s resilience to changes in climate and weather. Specifically, NOAA is working to…

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9 questions about climate change you were too embarrassed to ask

Basic answers to basic questions about global warming and the future climate.

by Brad Plumer , Umair Irfan , and Brian Resnick

This explainer was updated by Umair Irfan in December 2018 and draws heavily from a card stack written by Brad Plumer in 2015. Brian Resnick contributed the section on the Paris climate accord in 2017.

There’s a vast and growing gap between the urgency to fight climate change and the policies needed to combat it.

In 2018, the United Nations’ Intergovernmental Panel on Climate Change found that it is possible to limit global warming to 1.5 degrees Celsius this century, but the world may have as little as 12 years left to act. The US government’s National Climate Assessment , with input from NASA, the Environmental Protection Agency, and the Pentagon, also reported that the consequences of climate change are already here, ranging from nuisance flooding to the spread of mosquito-borne viruses into what were once colder climates. Left unchecked, warming will cost the US economy hundreds of billions of dollars.

However, these facts have failed to register with the Trump administration, which is actively pushing policies that will increase the emissions of heat-trapping gases.

Ever since he took office, President Donald Trump has rejected or undermined President Barack Obama’s signature climate achievements: the Paris climate agreement; the Clean Power Plan , the main domestic policy for limiting greenhouse gas emissions; and fuel economy standards , which target transportation, the largest US source of greenhouse gases.

At the same time, the Trump administration has aggressively boosted fossil fuels: opening unprecedented swaths of public lands to mining and drilling , attempting to bail out foundering coal power plants , and promoting hydrocarbon exploitation at climate change conferences .

Trump has also appointed climate change skeptics to key positions. Quietly, officials at these and other science agencies have been removing the words “climate change” from government websites and press releases.

Yet the evidence for humanity’s role in changing the climate continues to mount, and its consequences are increasingly difficult to ignore. Atmospheric carbon dioxide concentrations now top 408 parts per million, a threshold the planet hasn’t seen in millions of years . Greenhouse gas emissions reached a record high in 2018. Disasters worsened by climate change have taken hundreds of lives, destroyed thousands of homes, and cost billions of dollars.

The big questions now are how these ongoing changes in the climate will reverberate throughout the rest of the world, and what we should do about them. The answers bridge decades of research across geology, economics, and social science, which have been confounded by uncertainty and obscured by jargon. That’s why it can be a bit daunting to join the discussion for the first time, or to revisit the conversation after a hiatus.

To help, we’ve provided answers to some fundamental questions about climate change you may have been afraid to ask.

1) What is global warming?

In short: The world is getting hotter, and humans are responsible.

Yes, the planet’s temperature has changed before, but it’s the rise in average temperature of the Earth's climate system since the late 19th century, the dawn of the Industrial Revolution, that’s important here. Temperatures over land and ocean  have gone up  0.8° to 1° Celsius (1.4° to 1.8° Fahrenheit), on average, in that span:

Many people use the term “climate change” to describe this rise in temperatures and the associated effects on the Earth's climate. (The shift from the term “global warming” to “climate change” was also part of a deliberate messaging effort by a Republican pollster to undermine support for environmental regulations.)

Like detectives solving a murder, climate scientists have found humanity’s fingerprints all over the planet’s warming, with the overwhelming majority of the evidence pointing to the extra greenhouse gases humans have put into the atmosphere by burning fossil fuels. Greenhouse gases like carbon dioxide  trap heat  at the Earth’s surface, preventing that heat from escaping back out into space too quickly. When we burn coal, natural gas, or oil for energy, or when we cut down forests that usually soak up greenhouse gases, we  add even more  carbon dioxide to the atmosphere, so the planet warms up.

Global warming also refers to what scientists think will happen in the future if humans  keep  adding greenhouse gases to the atmosphere.

Though there is a steady stream of new studies on climate change, one of the most robust aggregations of the science remains the Intergovernmental Panel on Climate Change’s fifth assessment report from 2013. The IPCC is convened by the United Nations, and the report draws on more than 800 expert authors. It  projects  that temperatures could rise at least 2°C (3.6°F) by the end of the century under many plausible scenarios — and possibly 4°C or more. A more recent study by scientists in the United Kingdom found a narrower range of expected temperatures if atmospheric carbon dioxide doubled, rising between 2.2°C and 3.4°C.

Many experts consider 2°C of warming to be  unacceptably high , increasing the risk of deadly heat waves, droughts, flooding, and extinctions. Rising temperatures will drive up global sea levels as the world’s glaciers and ice sheets melt. Further global warming  could affect  everything from our ability to grow food to the spread of disease.

That’s why the IPCC put out another report in 2018 comparing 2°C of warming to a scenario with 1.5°C of warming . The researchers found that this half-degree difference is actually pretty important, since every bit of warming matters. Between the two outlooks, less warming means fewer people will have to move from coastal areas, natural weather events will be less severe, and economies will take a smaller hit.

However, limiting warming would likely require a complete overhaul of our energy system. Fossil fuels currently  provide just over 80 percent  of the world’s energy. To zero out emissions this century, we’d have to replace most of that with low-carbon sources like wind, solar, nuclear, geothermal, or carbon capture.

Beyond that, we may have to electrify everything that uses energy and start pulling greenhouse gases straight from the air. And to get on track for 1.5°C of warming, the world would have to halve greenhouse gas emissions from current levels by 2030.

That’s a staggering task, and there are huge technological and political hurdles standing in the way. As such, the world's nations have been slow to act on global warming — many of the existing targets for curbing greenhouse gas emissions are too weak , yet many countries are falling short of even these modest goals.

2) How do we know global warming is real?

The simplest way is through temperature measurements. Agencies in the United States, Europe, and Japan have  independently   analyzed   historical temperature data and reached the same conclusion: The Earth’s average surface temperature has risen roughly 0.8° Celsius (1.4° Fahrenheit) since the early 20th century.

But that’s not the only clue. Scientists have also noted that glaciers and ice sheets around the world are melting. Satellite observations since the 1970s have shown warming in the lower atmosphere. There’s more heat in the ocean, causing water to expand and sea levels to rise. Plants are flowering earlier in many parts of the world. There’s more humidity in the atmosphere.  Here’s  a summary from the National Oceanic and Atmospheric Administration:

These are all signs that the Earth really is getting warmer — and that it’s not just a glitch in the thermometers. That explains why climate scientists  say things like , “Warming in the climate system is unequivocal.” They’re really confident about this one.

3) How do we know humans are causing global warming?

Climate scientists say they are more than  95 percent certain that human influence has been the dominant cause of global warming since 1950. They’re about  as sure of this  as they are that cigarette smoke causes cancer.

Why are they so confident? In part because they have a good grasp of how greenhouse gases can warm the planet, in part because the theory fits the available evidence, and in part because alternate theories have been ruled out. Let's break it down in six steps:

1) Scientists have long known that  greenhouse gases  in the atmosphere — such as carbon dioxide, methane, or water vapor — absorb certain frequencies of infrared radiation and  scatter them back  toward the Earth. These gases essentially prevent heat from escaping too quickly back into space, trapping that radiation at the surface and keeping the planet warm.

2) Climate scientists also know that concentrations of greenhouse gases in the atmosphere  have grown significantly  since the Industrial Revolution. Carbon dioxide has risen 45 percent . Methane has risen more than 200 percent . Through some relatively straightforward chemistry and physics , scientists can trace these increases to human activities like burning oil, gas, and coal.

3) So it stands to reason that more greenhouse gases would lead to more heat. And indeed, satellite measurements have shown that less infrared radiation is escaping out  into space over time and instead  returning  to the Earth’s surface. That’s strong evidence that the greenhouse effect is increasing.

4) There are other human fingerprints  that suggest increased greenhouse gases are warming the planet. For instance, back in the 1960s, simple climate models predicted that global warming caused by more carbon dioxide would lead to cooling in the upper atmosphere (because the heat is getting trapped at the surface). Later satellite measurements confirmed  exactly that . Here are  a few  other  similar predictions  that have also been confirmed.

5) Meanwhile, climate scientists have ruled out other explanations for the rise in average temperatures over the past century. To take one example: Solar activity can shift from year to year, affecting the Earth's climate. But satellite data shows that total solar irradiance  has declined slightly  in the past 35 years, even as the Earth has warmed.

6) More  recent calculations  have shown that it’s impossible to explain the temperature rise we’ve seen in the past century without taking the increase in carbon dioxide and other greenhouse gases into account. Natural causes, like the sun or volcanoes, have an influence, but they’re not sufficient by themselves.

Ultimately, the Intergovernmental Panel on Climate Change  concluded  that most of the warming since 1951 has been due to human activities. The Earth’s climate can certainly fluctuate from year to year due to natural forces (including oscillations in the Pacific Ocean, such as  El Niño ). But greenhouse gases are driving the larger upward trend in temperatures.

And as the Climate Science Special Report , released by 13 US federal agencies in November 2017, put it, “For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”

More:  This chart breaks down all the different factors affecting the Earth’s average temperature. And there’s much more detail in the IPCC’s  report , particularly this section  and  this one .

4) How has global warming affected the world so far?

Here’s a list of ongoing changes that climate scientists have concluded are likely linked to global warming, as detailed by the IPCC  here  and  here .

Higher temperatures:  Every continent has warmed substantially since the 1950s. There are more hot days and fewer cold days, on average, and the hot days are hotter.

Heavier storms and floods:  The world’s atmosphere can hold more moisture as it warms. As a result, the overall number of heavier storms has increased since the mid-20th century, particularly in North America and Europe (though there’s plenty of regional variation). Scientists reported in December that at least 18 percent of Hurricane Harvey’s record-setting rainfall over Houston in August was due to climate change.

Heat waves:  Heat waves have become  longer and more frequent  around the world over the past 50 years, particularly in Europe, Asia, and Australia.

Shrinking sea ice:  The extent of sea ice in the Arctic, always at its maximum in winter, has shrunk since 1979, by 3.3 percent per decade. Summer sea ice has dwindled even more rapidly, by 13.2 percent per decade. Antarctica has seen recent years with record growth in sea ice, but it’s a very different environment than the Arctic, and the losses in the north far exceed any gains at the South Pole, so total global sea ice is on the decline:

Shrinking glaciers and ice sheets:  Glaciers around the world have, on average, been losing ice since the 1970s. In some areas, that  is reducing  the amount of available freshwater. The ice sheet on Greenland, which would raise global sea levels by 25 feet if it all melted, is declining, with some sections experiencing a sudden surge in the melt rate. The Antarctic ice sheet is also getting smaller, but at a much slower rate .

Sea level rise:  Global sea levels rose 9.8 inches (25 centimeters) in the 19th and 20th centuries, after 2,000 years  of relatively little change , and the pace is speeding up . Sea level rise is caused by both the thermal expansion of the oceans — as water warms up, it expands — and the melting of glaciers and ice sheets (but not sea ice).

Food supply:  A hotter climate can be both good for crops (it lengthens the growing season, and more carbon dioxide can increase photosynthesis) and bad for crops (excess heat can damage plants). The IPCC  found  that global warming was currently benefiting crops in some high-latitude areas but that negative effects are becoming increasingly common worldwide. In areas like California, crop yields are estimated to decline 40 percent by 2050.

Shifting species:  Many land and marine species  have had to shift  their geographic ranges in response to warmer temperatures. So far, several extinctions  have been linked  to global warming, such as certain frog species in Central America.

Warmer winters: In general, winters are warming faster than summers . Average low temperatures are rising all over the world. In some cases, these temperatures are climbing above the freezing point of water. We’re already seeing massive declines in snow accumulation in the United States, which can paradoxically increase flood, drought, and wildfire risk — as water that would ordinarily dispatch slowly over the course of a season instead flows through a region all at once.

Debated impacts

Here are a few other ways the Earth’s climate has been changing — but scientists are still debating whether and how they’re linked to global warming:

Droughts have become  more frequent and more intense  in some parts of the world — such as the American Southwest, Mediterranean Europe, and West Africa — though it’s hard to identify a clear global trend. In other parts of the world, such as the Midwestern United States and Northwestern Australia, droughts appear to have become  less  frequent. A recent study shows that, globally, the time between droughts is shrinking and more areas are affected by drought and taking longer to recover from them.

Hurricanes have clearly become more intense in the North Atlantic Ocean since 1970, the IPCC says. But it’s less clear whether global warming is driving this. 2017 was an exceptionally bad year for Atlantic hurricanes in terms of strength and damage. And while scientists are still uncertain whether they were a fluke or part of a trend, they are warning we should treat it as a baseline year. There doesn’t yet seem to be  any clear trajectory for tropical cyclones worldwide.

5) What impacts will global warming have in the future?

It depends on how much the planet actually heats up. The changes associated with 4° Celsius (or 7.2° Fahrenheit) of warming are expected to be more dramatic than the changes associated with 2°C of warming.

Here’s a basic rundown of big impacts we can expect if global warming continues, via the IPCC ( here  and  here ).

Hotter temperatures:  If emissions keep rising unchecked, then global average surface temperatures will be at least 2°C higher (3.6°F) than preindustrial levels by 2100 — and possibly 3°C or 4°C or more.

Higher sea level rise:  The expert consensus is that global sea levels will rise somewhere between 0.2 and 2 meters by the end of the century if global warming continues unchecked (that’s between 0.6 and 6.6 feet). That’s a wide range, reflecting some of the uncertainties scientists have in how ice will melt. In specific regions like the Eastern United States, sea level rise could be even higher, and around the world, the rate of rise is accelerating .

Heat waves:  A hotter planet will mean more frequent and severe heat waves .

Droughts and floods:  Across the globe, wet seasons are expected to become wetter, and dry seasons drier. As the IPCC  puts it , the world will see “more intense downpours, leading to more floods, yet longer dry periods between rain events, leading to more drought.”

Hurricanes:  It’s not yet clear what impact global warming will have on tropical cyclones. The IPCC  said  it was likely that tropical cyclones would get stronger as the oceans heat up, with faster winds and heavier rainfall. But the overall number of hurricanes in many regions was likely to “either decrease or remain essentially unchanged.”

Heavier storm surges:  Higher sea levels will  increase the risk of storm surges  and flooding when storms do hit.

Agriculture:  In many parts of the world, the mix of increased heat and drought is expected to make food production more difficult. The IPCC  concluded  that global warming of 1°C or more could start hurting crop yields for wheat, corn, and rice by the 2030s, especially in the tropics. (This wouldn’t be uniform, however; some crops may benefit from mild warming, such as winter wheat in the United States.)

Extinctions:  As the world warms, many plant and animal species will need to shift habitats at a rapid rate to maintain their current conditions. Some species will be able to keep up; others likely won’t. The Great Barrier Reef, for instance, may not be able to recover from major recent bleaching events linked to climate change. The National Research Council  has estimated  that a mass extinction event “could conceivably occur before the year 2100.”

Long-term changes:  Most of the projected changes above will occur in the 21st century. But temperatures will keep rising after that if greenhouse gas levels aren’t stabilized. That increases the risk of more drastic longer-term shifts. One example: If West Antarctica’s ice sheet started crumbling, that could push sea levels up significantly. The National Research Council in 2013 deemed  many of these rapid climate surprises unlikely this century but a real possibility further into the future.

6) What happens if the world heats up more drastically — say, 4°C?

The risks of climate change would rise considerably if temperatures rose 4° Celsius (7.2° Fahrenheit) above preindustrial levels — something that’s possible if greenhouse gas emissions keep rising at their current rate.

The IPCC  says  4°C of global warming could lead to “substantial species extinctions,” “large risks to global and regional food security,” and the risk of irreversibly destabilizing Greenland’s massive ice sheet.

One huge concern is food production: A  growing   number  of  studies suggest it would become significantly more difficult for the world to grow food with 3°C or 4°C of global warming. Countries like Bangladesh, Egypt, Vietnam, and parts of Africa could see large tracts of farmland turn unusable due to rising seas. Scientists are also concerned about crops getting less nutritious due to rising CO2.

Humans could struggle to adapt to these conditions. Many people might think the impacts of 4°C of warming will simply be twice as bad as those of 2°C. But as a 2013 World Bank  report argued, that’s not necessarily true. Impacts may interact with each other in unpredictable ways. Current agriculture models, for instance, don’t have a good sense of what will happen to crops if increased heat waves, droughts, new pests and diseases, and other changes all start to combine.

“Given that uncertainty remains about the full nature and scale of impacts,” the World Bank report said, “there is also no certainty that adaptation to a 4°C world is possible.” Its conclusion was blunt: “The projected 4°C warming simply must not be allowed to occur.”

7) What do climate models say about the warming that could actually happen in the coming decades?

That depends on your faith in humanity.

Climate models depend on not only complicated physics but the intricacies of human behavior over the entire planet.

Generally, the more greenhouse gases humanity pumps into the atmosphere, the warmer it will get. But scientists aren’t certain how sensitive the global climate system is to increases in greenhouse gases. And just how much we might emit over the coming decades remains an open question, depending on advances in technology and international efforts to cut emissions.

The IPCC groups these scenarios into four categories of atmospheric greenhouse gas concentrations known as Representative Concentration Pathways . They serve as standard benchmarks for evaluating climate models, but they also have some assumptions baked in .

RCP 2.6, also called RCP 3PD, is the scenario with very low greenhouse gas concentrations in the atmosphere. It bets on declining oil use, a population of 9 billion by 2100, increasing energy efficiency, and emissions holding steady until 2020, at which point they’ll decline and even go negative by 2100. This is, to put it mildly, very optimistic.

The next tier up is RCP 4.5, which still banks on ambitious reductions in emissions but anticipates an inflection point in the emissions rate around 2040. RCP 6 expects emissions to increase 75 percent above today’s levels before peaking and declining around 2060 as the world continues to rely heavily on fossil fuels.

The highest tier, RCP 8.5, is the pessimistic business-as-usual scenario, anticipating no policy changes nor any technological advances. It expects a global population of 12 billion and triple the rate of carbon dioxide emissions compared to today by 2100.

Here’s how greenhouse gas emissions under each scenario stack up next to each other:

And here’s what that means for global average temperatures, assuming that a doubling of carbon dioxide concentrations in the atmosphere leads to 3°C of warming:

As you can see, RCP 3PD is the only trajectory that keeps the planet below 2°C of warming. Recall what it would take to keep emissions in line with this pathway and you’ll understand the enormity of the challenge of meeting this goal.

8) How do we stop global warming?

The world’s nations would need to cut  their greenhouse gas emissions by a lot. And even that wouldn’t stop all global warming.

For example, let’s say we wanted to limit global warming to below 2°C. To do that, the IPCC  has calculated  that annual greenhouse gas emissions would need to drop at least 40 to 70 percent by midcentury.

Emissions would then have to keep falling until humans were hardly emitting any extra greenhouse gases by the end of the century. We’d also have to remove carbon dioxide from the atmosphere .

Cutting emissions that sharply is a daunting task. Right now, the world gets  87 percent  of its primary energy from fossil fuels: oil, gas, and coal. By contrast, just 13 percent of the world’s primary energy is “low carbon”: a little bit of wind and solar power, some nuclear power plants, a bunch of hydroelectric dams. That’s one reason global emissions keep rising each year.

To stay below 2°C, that would all need to change radically. By 2050, the IPCC notes, the world would need to triple or even quadruple the share of clean energy it uses — and keep scaling it up thereafter. Second, we’d have to get dramatically more efficient at using energy in our homes, buildings, and cars. And stop cutting down forests. And reduce emissions from agriculture and from industrial processes like cement manufacturing.

The IPCC also notes that this task becomes even more difficult the longer we put it off, because carbon dioxide and other greenhouse gases will keep piling up in the atmosphere in the meantime, and the cuts necessary to stay below the 2°C limit become more severe.

9) What are we actually doing to fight climate change?

A global problem requires global action, but with climate change, there is a yawning gap between ambition and action.

The main international effort is the 2015 Paris climate accord, of which the United States is the only country in the world that wants out . The deal was hammered out over weeks of tense negotiations and weighs in at 31 pages . What it does is actually pretty simple.

The backbone is the global target of keeping global average temperatures from rising 2°C (compared to temperatures before the Industrial Revolution) by the end of the century. Beyond 2 degrees, we risk dramatically higher seas, changes in weather patterns, food and water crises, and an overall more hostile world.

Critics have argued that the 2-degree mark is arbitrary, or even too low , to make a difference. But it’s a starting point, a goal that, before Paris, the world was on track to wildly miss.

Paris is voluntary

To accomplish this 2-degree goal, the accord states that countries should strive to reach peak emissions “as soon as possible.” (Currently, we’re on track to hit peak emissions around 2030 or later , which will likely be too late.)

But the agreement doesn’t detail exactly how these countries should do that. Instead, it provides a framework for getting momentum going on greenhouse gas reduction, with some oversight and accountability. For the US, the pledge involves 26 to 28 percent reductions by 2025. (Under Trump’s current policies, that goal is impossible .)

There’s also no defined punishment for breaking it. The idea is to create a culture of accountability (and maybe some peer pressure) to get countries to step up their climate game.

In 2020, delegates are supposed to reconvene and provide updates about their emission pledges and report on how they’re becoming more aggressive on accomplishing the 2-degree goal.

However, many countries are already falling behind on their climate change commitments, and some, like Germany, are giving up on their near-term targets.

Paris asks richer countries to help out poorer countries

There’s a fundamental inequality when it comes to global emissions. Rich countries have plundered and burned huge amounts of fossil fuels and gotten rich from them. Poor countries seeking to grow their economies are now being admonished for using the same fuels. Many low-lying poor countries also will be among the first to bear the worst impacts of climate change.

The main vehicle for rectifying this is the Green Climate Fund , via which richer countries, like the US, are supposed to send $100 billion a year in aid and financing by 2020 to the poorer countries. The United States’ share was $3 billion , but with President Trump’s decision to withdraw from the Paris accord, this goal is unlikely to be met.

The agreement matters because we absolutely need momentum on this issue

The Paris agreement is largely symbolic, and it will live on even though Trump is aiming to pull the US out. But, as Jim Tankersley wrote for Vox , “the accord will be weakened, and, much more importantly, so will the fragile international coalition” around climate change.

We’re already seeing the Paris agreement lose steam. At a follow-up climate meeting this year in Katowice, Poland , negotiators forged an agreement on measuring and verifying their progress in cutting greenhouse gases, but left many critical questions of how to achieve these reductions unanswered.

But the Paris accord isn’t the only international climate policy game in town

There are regional international climate efforts like the European Union’s Emissions Trading System . However, the most effective global policy at keeping warming in check to date doesn’t have to do with climate change, at least on the surface.

The 1987 Montreal Protocol , which was convened by countries to halt the destruction of the ozone layer, had a major side effect of averting warming. In fact, it’s been the single most effective effort humanity has undertaken to fight climate change. Since many of the substances that eat away at the ozone layer are potent heat-trappers, limiting emissions of gases like chlorofluorocarbons has an outsize effect.

And the Trump administration doesn’t appear as hostile to Montreal as it does to Paris. The White House may send the 2016 Kigali Amendment to the Montreal Protocol to the Senate for ratification, giving the new regulations the force of law. If implemented, the amendment would avert 0.5°C of warming by 2100.

Regardless of what path we choose, the key thing to remember is that we are going to pay for climate change one way or another. We have the opportunity now to address warming on our own terms, with investments in clean energy, moving people away from disaster-prone areas, and regulating greenhouse gas emissions. Otherwise, we’ll pay through diminished crop harvests, inundated coastlines, destroyed homes, lost lives, and an increasingly unlivable planet. Ignoring or stalling on climate change chooses the latter option by default. Our choices do matter, but we’re running out of time to make them.

Further reading:

Avoiding catastrophic climate change isn’t impossible yet. Just incredibly hard.

Reckoning with climate change will demand ugly tradeoffs from environmentalists — and everyone else

Show this cartoon to anyone who doubts we need huge action on climate change

It’s time to start talking about “negative” carbon dioxide emissions

A history of the 2°C global warming target  

Scientists made a detailed “roadmap” for meeting the Paris climate goals. It’s eye-opening.

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A review of the global climate change impacts, adaptation, and sustainable mitigation measures

Kashif abbass.

1 School of Economics and Management, Nanjing University of Science and Technology, Nanjing, 210094 People’s Republic of China

Muhammad Zeeshan Qasim

2 Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, 210094 People’s Republic of China

Huaming Song

Muntasir murshed.

3 School of Business and Economics, North South University, Dhaka, 1229 Bangladesh

4 Department of Journalism, Media and Communications, Daffodil International University, Dhaka, Bangladesh

Haider Mahmood

5 Department of Finance, College of Business Administration, Prince Sattam Bin Abdulaziz University, 173, Alkharj, 11942 Saudi Arabia

Ijaz Younis

Associated data.

Data sources and relevant links are provided in the paper to access data.

Climate change is a long-lasting change in the weather arrays across tropics to polls. It is a global threat that has embarked on to put stress on various sectors. This study is aimed to conceptually engineer how climate variability is deteriorating the sustainability of diverse sectors worldwide. Specifically, the agricultural sector’s vulnerability is a globally concerning scenario, as sufficient production and food supplies are threatened due to irreversible weather fluctuations. In turn, it is challenging the global feeding patterns, particularly in countries with agriculture as an integral part of their economy and total productivity. Climate change has also put the integrity and survival of many species at stake due to shifts in optimum temperature ranges, thereby accelerating biodiversity loss by progressively changing the ecosystem structures. Climate variations increase the likelihood of particular food and waterborne and vector-borne diseases, and a recent example is a coronavirus pandemic. Climate change also accelerates the enigma of antimicrobial resistance, another threat to human health due to the increasing incidence of resistant pathogenic infections. Besides, the global tourism industry is devastated as climate change impacts unfavorable tourism spots. The methodology investigates hypothetical scenarios of climate variability and attempts to describe the quality of evidence to facilitate readers’ careful, critical engagement. Secondary data is used to identify sustainability issues such as environmental, social, and economic viability. To better understand the problem, gathered the information in this report from various media outlets, research agencies, policy papers, newspapers, and other sources. This review is a sectorial assessment of climate change mitigation and adaptation approaches worldwide in the aforementioned sectors and the associated economic costs. According to the findings, government involvement is necessary for the country’s long-term development through strict accountability of resources and regulations implemented in the past to generate cutting-edge climate policy. Therefore, mitigating the impacts of climate change must be of the utmost importance, and hence, this global threat requires global commitment to address its dreadful implications to ensure global sustenance.

Introduction

Worldwide observed and anticipated climatic changes for the twenty-first century and global warming are significant global changes that have been encountered during the past 65 years. Climate change (CC) is an inter-governmental complex challenge globally with its influence over various components of the ecological, environmental, socio-political, and socio-economic disciplines (Adger et al.  2005 ; Leal Filho et al.  2021 ; Feliciano et al.  2022 ). Climate change involves heightened temperatures across numerous worlds (Battisti and Naylor  2009 ; Schuurmans  2021 ; Weisheimer and Palmer  2005 ; Yadav et al.  2015 ). With the onset of the industrial revolution, the problem of earth climate was amplified manifold (Leppänen et al.  2014 ). It is reported that the immediate attention and due steps might increase the probability of overcoming its devastating impacts. It is not plausible to interpret the exact consequences of climate change (CC) on a sectoral basis (Izaguirre et al.  2021 ; Jurgilevich et al.  2017 ), which is evident by the emerging level of recognition plus the inclusion of climatic uncertainties at both local and national level of policymaking (Ayers et al.  2014 ).

Climate change is characterized based on the comprehensive long-haul temperature and precipitation trends and other components such as pressure and humidity level in the surrounding environment. Besides, the irregular weather patterns, retreating of global ice sheets, and the corresponding elevated sea level rise are among the most renowned international and domestic effects of climate change (Lipczynska-Kochany  2018 ; Michel et al.  2021 ; Murshed and Dao 2020 ). Before the industrial revolution, natural sources, including volcanoes, forest fires, and seismic activities, were regarded as the distinct sources of greenhouse gases (GHGs) such as CO 2 , CH 4 , N 2 O, and H 2 O into the atmosphere (Murshed et al. 2020 ; Hussain et al.  2020 ; Sovacool et al.  2021 ; Usman and Balsalobre-Lorente 2022 ; Murshed 2022 ). United Nations Framework Convention on Climate Change (UNFCCC) struck a major agreement to tackle climate change and accelerate and intensify the actions and investments required for a sustainable low-carbon future at Conference of the Parties (COP-21) in Paris on December 12, 2015. The Paris Agreement expands on the Convention by bringing all nations together for the first time in a single cause to undertake ambitious measures to prevent climate change and adapt to its impacts, with increased funding to assist developing countries in doing so. As so, it marks a turning point in the global climate fight. The core goal of the Paris Agreement is to improve the global response to the threat of climate change by keeping the global temperature rise this century well below 2 °C over pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5° C (Sharma et al. 2020 ; Sharif et al. 2020 ; Chien et al. 2021 .

Furthermore, the agreement aspires to strengthen nations’ ability to deal with the effects of climate change and align financing flows with low GHG emissions and climate-resilient paths (Shahbaz et al. 2019 ; Anwar et al. 2021 ; Usman et al. 2022a ). To achieve these lofty goals, adequate financial resources must be mobilized and provided, as well as a new technology framework and expanded capacity building, allowing developing countries and the most vulnerable countries to act under their respective national objectives. The agreement also establishes a more transparent action and support mechanism. All Parties are required by the Paris Agreement to do their best through “nationally determined contributions” (NDCs) and to strengthen these efforts in the coming years (Balsalobre-Lorente et al. 2020 ). It includes obligations that all Parties regularly report on their emissions and implementation activities. A global stock-take will be conducted every five years to review collective progress toward the agreement’s goal and inform the Parties’ future individual actions. The Paris Agreement became available for signature on April 22, 2016, Earth Day, at the United Nations Headquarters in New York. On November 4, 2016, it went into effect 30 days after the so-called double threshold was met (ratification by 55 nations accounting for at least 55% of world emissions). More countries have ratified and continue to ratify the agreement since then, bringing 125 Parties in early 2017. To fully operationalize the Paris Agreement, a work program was initiated in Paris to define mechanisms, processes, and recommendations on a wide range of concerns (Murshed et al. 2021 ). Since 2016, Parties have collaborated in subsidiary bodies (APA, SBSTA, and SBI) and numerous formed entities. The Conference of the Parties functioning as the meeting of the Parties to the Paris Agreement (CMA) convened for the first time in November 2016 in Marrakesh in conjunction with COP22 and made its first two resolutions. The work plan is scheduled to be finished by 2018. Some mitigation and adaptation strategies to reduce the emission in the prospective of Paris agreement are following firstly, a long-term goal of keeping the increase in global average temperature to well below 2 °C above pre-industrial levels, secondly, to aim to limit the rise to 1.5 °C, since this would significantly reduce risks and the impacts of climate change, thirdly, on the need for global emissions to peak as soon as possible, recognizing that this will take longer for developing countries, lastly, to undertake rapid reductions after that under the best available science, to achieve a balance between emissions and removals in the second half of the century. On the other side, some adaptation strategies are; strengthening societies’ ability to deal with the effects of climate change and to continue & expand international assistance for developing nations’ adaptation.

However, anthropogenic activities are currently regarded as most accountable for CC (Murshed et al. 2022 ). Apart from the industrial revolution, other anthropogenic activities include excessive agricultural operations, which further involve the high use of fuel-based mechanization, burning of agricultural residues, burning fossil fuels, deforestation, national and domestic transportation sectors, etc. (Huang et al.  2016 ). Consequently, these anthropogenic activities lead to climatic catastrophes, damaging local and global infrastructure, human health, and total productivity. Energy consumption has mounted GHGs levels concerning warming temperatures as most of the energy production in developing countries comes from fossil fuels (Balsalobre-Lorente et al. 2022 ; Usman et al. 2022b ; Abbass et al. 2021a ; Ishikawa-Ishiwata and Furuya  2022 ).

This review aims to highlight the effects of climate change in a socio-scientific aspect by analyzing the existing literature on various sectorial pieces of evidence globally that influence the environment. Although this review provides a thorough examination of climate change and its severe affected sectors that pose a grave danger for global agriculture, biodiversity, health, economy, forestry, and tourism, and to purpose some practical prophylactic measures and mitigation strategies to be adapted as sound substitutes to survive from climate change (CC) impacts. The societal implications of irregular weather patterns and other effects of climate changes are discussed in detail. Some numerous sustainable mitigation measures and adaptation practices and techniques at the global level are discussed in this review with an in-depth focus on its economic, social, and environmental aspects. Methods of data collection section are included in the supplementary information.

Review methodology

Related study and its objectives.

Today, we live an ordinary life in the beautiful digital, globalized world where climate change has a decisive role. What happens in one country has a massive influence on geographically far apart countries, which points to the current crisis known as COVID-19 (Sarkar et al.  2021 ). The most dangerous disease like COVID-19 has affected the world’s climate changes and economic conditions (Abbass et al. 2022 ; Pirasteh-Anosheh et al.  2021 ). The purpose of the present study is to review the status of research on the subject, which is based on “Global Climate Change Impacts, adaptation, and sustainable mitigation measures” by systematically reviewing past published and unpublished research work. Furthermore, the current study seeks to comment on research on the same topic and suggest future research on the same topic. Specifically, the present study aims: The first one is, organize publications to make them easy and quick to find. Secondly, to explore issues in this area, propose an outline of research for future work. The third aim of the study is to synthesize the previous literature on climate change, various sectors, and their mitigation measurement. Lastly , classify the articles according to the different methods and procedures that have been adopted.

Review methodology for reviewers

This review-based article followed systematic literature review techniques that have proved the literature review as a rigorous framework (Benita  2021 ; Tranfield et al.  2003 ). Moreover, we illustrate in Fig.  1 the search method that we have started for this research. First, finalized the research theme to search literature (Cooper et al.  2018 ). Second, used numerous research databases to search related articles and download from the database (Web of Science, Google Scholar, Scopus Index Journals, Emerald, Elsevier Science Direct, Springer, and Sciverse). We focused on various articles, with research articles, feedback pieces, short notes, debates, and review articles published in scholarly journals. Reports used to search for multiple keywords such as “Climate Change,” “Mitigation and Adaptation,” “Department of Agriculture and Human Health,” “Department of Biodiversity and Forestry,” etc.; in summary, keyword list and full text have been made. Initially, the search for keywords yielded a large amount of literature.

Methodology search for finalized articles for investigations.

Source : constructed by authors

Since 2020, it has been impossible to review all the articles found; some restrictions have been set for the literature exhibition. The study searched 95 articles on a different database mentioned above based on the nature of the study. It excluded 40 irrelevant papers due to copied from a previous search after readings tiles, abstract and full pieces. The criteria for inclusion were: (i) articles focused on “Global Climate Change Impacts, adaptation, and sustainable mitigation measures,” and (ii) the search key terms related to study requirements. The complete procedure yielded 55 articles for our study. We repeat our search on the “Web of Science and Google Scholars” database to enhance the search results and check the referenced articles.

In this study, 55 articles are reviewed systematically and analyzed for research topics and other aspects, such as the methods, contexts, and theories used in these studies. Furthermore, this study analyzes closely related areas to provide unique research opportunities in the future. The study also discussed future direction opportunities and research questions by understanding the research findings climate changes and other affected sectors. The reviewed paper framework analysis process is outlined in Fig.  2 .

Framework of the analysis Process.

Natural disasters and climate change’s socio-economic consequences

Natural and environmental disasters can be highly variable from year to year; some years pass with very few deaths before a significant disaster event claims many lives (Symanski et al.  2021 ). Approximately 60,000 people globally died from natural disasters each year on average over the past decade (Ritchie and Roser  2014 ; Wiranata and Simbolon  2021 ). So, according to the report, around 0.1% of global deaths. Annual variability in the number and share of deaths from natural disasters in recent decades are shown in Fig.  3 . The number of fatalities can be meager—sometimes less than 10,000, and as few as 0.01% of all deaths. But shock events have a devastating impact: the 1983–1985 famine and drought in Ethiopia; the 2004 Indian Ocean earthquake and tsunami; Cyclone Nargis, which struck Myanmar in 2008; and the 2010 Port-au-Prince earthquake in Haiti and now recent example is COVID-19 pandemic (Erman et al.  2021 ). These events pushed global disaster deaths to over 200,000—more than 0.4% of deaths in these years. Low-frequency, high-impact events such as earthquakes and tsunamis are not preventable, but such high losses of human life are. Historical evidence shows that earlier disaster detection, more robust infrastructure, emergency preparedness, and response programmers have substantially reduced disaster deaths worldwide. Low-income is also the most vulnerable to disasters; improving living conditions, facilities, and response services in these areas would be critical in reducing natural disaster deaths in the coming decades.

Global deaths from natural disasters, 1978 to 2020.

Source EMDAT ( 2020 )

The interior regions of the continent are likely to be impacted by rising temperatures (Dimri et al.  2018 ; Goes et al.  2020 ; Mannig et al.  2018 ; Schuurmans  2021 ). Weather patterns change due to the shortage of natural resources (water), increase in glacier melting, and rising mercury are likely to cause extinction to many planted species (Gampe et al.  2016 ; Mihiretu et al.  2021 ; Shaffril et al.  2018 ).On the other hand, the coastal ecosystem is on the verge of devastation (Perera et al.  2018 ; Phillips  2018 ). The temperature rises, insect disease outbreaks, health-related problems, and seasonal and lifestyle changes are persistent, with a strong probability of these patterns continuing in the future (Abbass et al. 2021c ; Hussain et al.  2018 ). At the global level, a shortage of good infrastructure and insufficient adaptive capacity are hammering the most (IPCC  2013 ). In addition to the above concerns, a lack of environmental education and knowledge, outdated consumer behavior, a scarcity of incentives, a lack of legislation, and the government’s lack of commitment to climate change contribute to the general public’s concerns. By 2050, a 2 to 3% rise in mercury and a drastic shift in rainfall patterns may have serious consequences (Huang et al. 2022 ; Gorst et al.  2018 ). Natural and environmental calamities caused huge losses globally, such as decreased agriculture outputs, rehabilitation of the system, and rebuilding necessary technologies (Ali and Erenstein  2017 ; Ramankutty et al.  2018 ; Yu et al.  2021 ) (Table ​ (Table1). 1 ). Furthermore, in the last 3 or 4 years, the world has been plagued by smog-related eye and skin diseases, as well as a rise in road accidents due to poor visibility.

Main natural danger statistics for 1985–2020 at the global level

Key natural hazards statistics from 1978 to 2020
Country	1978 change	2018	Absolute change	Relative
Drought	63	0	− 63	− 100%
Earthquake	25,162	4,321	− 20,841	− 83%
Extreme temperature	150	536	+ 386	+ 257%
Extreme weather	3676	1,666	− 2,010	− 55%
Flood	5,897	2,869	− 3,028	− 51%
Landslide	86	275	+ 189	+ 220%
Mass movement	50	17	− 33	− 66%
Volcanic activity	268	878	+ 610	+ 228%
Wildfire	2	247	+ 245	+ 12,250%
All − natural disasters	35,036	10,809	− 24,227	− 69%

Source: EM-DAT ( 2020 )

Climate change and agriculture

Global agriculture is the ultimate sector responsible for 30–40% of all greenhouse emissions, which makes it a leading industry predominantly contributing to climate warming and significantly impacted by it (Grieg; Mishra et al.  2021 ; Ortiz et al.  2021 ; Thornton and Lipper  2014 ). Numerous agro-environmental and climatic factors that have a dominant influence on agriculture productivity (Pautasso et al.  2012 ) are significantly impacted in response to precipitation extremes including floods, forest fires, and droughts (Huang  2004 ). Besides, the immense dependency on exhaustible resources also fuels the fire and leads global agriculture to become prone to devastation. Godfray et al. ( 2010 ) mentioned that decline in agriculture challenges the farmer’s quality of life and thus a significant factor to poverty as the food and water supplies are critically impacted by CC (Ortiz et al.  2021 ; Rosenzweig et al.  2014 ). As an essential part of the economic systems, especially in developing countries, agricultural systems affect the overall economy and potentially the well-being of households (Schlenker and Roberts  2009 ). According to the report published by the Intergovernmental Panel on Climate Change (IPCC), atmospheric concentrations of greenhouse gases, i.e., CH 4, CO 2 , and N 2 O, are increased in the air to extraordinary levels over the last few centuries (Usman and Makhdum 2021 ; Stocker et al.  2013 ). Climate change is the composite outcome of two different factors. The first is the natural causes, and the second is the anthropogenic actions (Karami 2012 ). It is also forecasted that the world may experience a typical rise in temperature stretching from 1 to 3.7 °C at the end of this century (Pachauri et al. 2014 ). The world’s crop production is also highly vulnerable to these global temperature-changing trends as raised temperatures will pose severe negative impacts on crop growth (Reidsma et al. 2009 ). Some of the recent modeling about the fate of global agriculture is briefly described below.

Decline in cereal productivity

Crop productivity will also be affected dramatically in the next few decades due to variations in integral abiotic factors such as temperature, solar radiation, precipitation, and CO 2 . These all factors are included in various regulatory instruments like progress and growth, weather-tempted changes, pest invasions (Cammell and Knight 1992 ), accompanying disease snags (Fand et al. 2012 ), water supplies (Panda et al. 2003 ), high prices of agro-products in world’s agriculture industry, and preeminent quantity of fertilizer consumption. Lobell and field ( 2007 ) claimed that from 1962 to 2002, wheat crop output had condensed significantly due to rising temperatures. Therefore, during 1980–2011, the common wheat productivity trends endorsed extreme temperature events confirmed by Gourdji et al. ( 2013 ) around South Asia, South America, and Central Asia. Various other studies (Asseng, Cao, Zhang, and Ludwig 2009 ; Asseng et al. 2013 ; García et al. 2015 ; Ortiz et al. 2021 ) also proved that wheat output is negatively affected by the rising temperatures and also caused adverse effects on biomass productivity (Calderini et al. 1999 ; Sadras and Slafer 2012 ). Hereafter, the rice crop is also influenced by the high temperatures at night. These difficulties will worsen because the temperature will be rising further in the future owing to CC (Tebaldi et al. 2006 ). Another research conducted in China revealed that a 4.6% of rice production per 1 °C has happened connected with the advancement in night temperatures (Tao et al. 2006 ). Moreover, the average night temperature growth also affected rice indicia cultivar’s output pragmatically during 25 years in the Philippines (Peng et al. 2004 ). It is anticipated that the increase in world average temperature will also cause a substantial reduction in yield (Hatfield et al. 2011 ; Lobell and Gourdji 2012 ). In the southern hemisphere, Parry et al. ( 2007 ) noted a rise of 1–4 °C in average daily temperatures at the end of spring season unti the middle of summers, and this raised temperature reduced crop output by cutting down the time length for phenophases eventually reduce the yield (Hatfield and Prueger 2015 ; R. Ortiz 2008 ). Also, world climate models have recommended that humid and subtropical regions expect to be plentiful prey to the upcoming heat strokes (Battisti and Naylor 2009 ). Grain production is the amalgamation of two constituents: the average weight and the grain output/m 2 , however, in crop production. Crop output is mainly accredited to the grain quantity (Araus et al. 2008 ; Gambín and Borrás 2010 ). In the times of grain set, yield resources are mainly strewn between hitherto defined components, i.e., grain usual weight and grain output, which presents a trade-off between them (Gambín and Borrás 2010 ) beside disparities in per grain integration (B. L. Gambín et al. 2006 ). In addition to this, the maize crop is also susceptible to raised temperatures, principally in the flowering stage (Edreira and Otegui 2013 ). In reality, the lower grain number is associated with insufficient acclimatization due to intense photosynthesis and higher respiration and the high-temperature effect on the reproduction phenomena (Edreira and Otegui 2013 ). During the flowering phase, maize visible to heat (30–36 °C) seemed less anthesis-silking intermissions (Edreira et al. 2011 ). Another research by Dupuis and Dumas ( 1990 ) proved that a drop in spikelet when directly visible to high temperatures above 35 °C in vitro pollination. Abnormalities in kernel number claimed by Vega et al. ( 2001 ) is related to conceded plant development during a flowering phase that is linked with the active ear growth phase and categorized as a critical phase for approximation of kernel number during silking (Otegui and Bonhomme 1998 ).

The retort of rice output to high temperature presents disparities in flowering patterns, and seed set lessens and lessens grain weight (Qasim et al. 2020 ; Qasim, Hammad, Maqsood, Tariq, & Chawla). During the daytime, heat directly impacts flowers which lessens the thesis period and quickens the earlier peak flowering (Tao et al. 2006 ). Antagonistic effect of higher daytime temperature d on pollen sprouting proposed seed set decay, whereas, seed set was lengthily reduced than could be explicated by pollen growing at high temperatures 40◦C (Matsui et al. 2001 ).

The decline in wheat output is linked with higher temperatures, confirmed in numerous studies (Semenov 2009 ; Stone and Nicolas 1994 ). High temperatures fast-track the arrangements of plant expansion (Blum et al. 2001 ), diminution photosynthetic process (Salvucci and Crafts‐Brandner 2004 ), and also considerably affect the reproductive operations (Farooq et al. 2011 ).

The destructive impacts of CC induced weather extremes to deteriorate the integrity of crops (Chaudhary et al. 2011 ), e.g., Spartan cold and extreme fog cause falling and discoloration of betel leaves (Rosenzweig et al. 2001 ), giving them a somehow reddish appearance, squeezing of lemon leaves (Pautasso et al. 2012 ), as well as root rot of pineapple, have reported (Vedwan and Rhoades 2001 ). Henceforth, in tackling the disruptive effects of CC, several short-term and long-term management approaches are the crucial need of time (Fig.  4 ). Moreover, various studies (Chaudhary et al. 2011 ; Patz et al. 2005 ; Pautasso et al. 2012 ) have demonstrated adapting trends such as ameliorating crop diversity can yield better adaptability towards CC.

Schematic description of potential impacts of climate change on the agriculture sector and the appropriate mitigation and adaptation measures to overcome its impact.

Climate change impacts on biodiversity

Global biodiversity is among the severe victims of CC because it is the fastest emerging cause of species loss. Studies demonstrated that the massive scale species dynamics are considerably associated with diverse climatic events (Abraham and Chain 1988 ; Manes et al. 2021 ; A. M. D. Ortiz et al. 2021 ). Both the pace and magnitude of CC are altering the compatible habitat ranges for living entities of marine, freshwater, and terrestrial regions. Alterations in general climate regimes influence the integrity of ecosystems in numerous ways, such as variation in the relative abundance of species, range shifts, changes in activity timing, and microhabitat use (Bates et al. 2014 ). The geographic distribution of any species often depends upon its ability to tolerate environmental stresses, biological interactions, and dispersal constraints. Hence, instead of the CC, the local species must only accept, adapt, move, or face extinction (Berg et al. 2010 ). So, the best performer species have a better survival capacity for adjusting to new ecosystems or a decreased perseverance to survive where they are already situated (Bates et al. 2014 ). An important aspect here is the inadequate habitat connectivity and access to microclimates, also crucial in raising the exposure to climate warming and extreme heatwave episodes. For example, the carbon sequestration rates are undergoing fluctuations due to climate-driven expansion in the range of global mangroves (Cavanaugh et al. 2014 ).

Similarly, the loss of kelp-forest ecosystems in various regions and its occupancy by the seaweed turfs has set the track for elevated herbivory by the high influx of tropical fish populations. Not only this, the increased water temperatures have exacerbated the conditions far away from the physiological tolerance level of the kelp communities (Vergés et al. 2016 ; Wernberg et al. 2016 ). Another pertinent danger is the devastation of keystone species, which even has more pervasive effects on the entire communities in that habitat (Zarnetske et al. 2012 ). It is particularly important as CC does not specify specific populations or communities. Eventually, this CC-induced redistribution of species may deteriorate carbon storage and the net ecosystem productivity (Weed et al. 2013 ). Among the typical disruptions, the prominent ones include impacts on marine and terrestrial productivity, marine community assembly, and the extended invasion of toxic cyanobacteria bloom (Fossheim et al. 2015 ).

The CC-impacted species extinction is widely reported in the literature (Beesley et al. 2019 ; Urban 2015 ), and the predictions of demise until the twenty-first century are dreadful (Abbass et al. 2019 ; Pereira et al. 2013 ). In a few cases, northward shifting of species may not be formidable as it allows mountain-dwelling species to find optimum climates. However, the migrant species may be trapped in isolated and incompatible habitats due to losing topography and range (Dullinger et al. 2012 ). For example, a study indicated that the American pika has been extirpated or intensely diminished in some regions, primarily attributed to the CC-impacted extinction or at least local extirpation (Stewart et al. 2015 ). Besides, the anticipation of persistent responses to the impacts of CC often requires data records of several decades to rigorously analyze the critical pre and post CC patterns at species and ecosystem levels (Manes et al. 2021 ; Testa et al. 2018 ).

Nonetheless, the availability of such long-term data records is rare; hence, attempts are needed to focus on these profound aspects. Biodiversity is also vulnerable to the other associated impacts of CC, such as rising temperatures, droughts, and certain invasive pest species. For instance, a study revealed the changes in the composition of plankton communities attributed to rising temperatures. Henceforth, alterations in such aquatic producer communities, i.e., diatoms and calcareous plants, can ultimately lead to variation in the recycling of biological carbon. Moreover, such changes are characterized as a potential contributor to CO 2 differences between the Pleistocene glacial and interglacial periods (Kohfeld et al. 2005 ).

Climate change implications on human health

It is an understood corporality that human health is a significant victim of CC (Costello et al. 2009 ). According to the WHO, CC might be responsible for 250,000 additional deaths per year during 2030–2050 (Watts et al. 2015 ). These deaths are attributed to extreme weather-induced mortality and morbidity and the global expansion of vector-borne diseases (Lemery et al. 2021; Yang and Usman 2021 ; Meierrieks 2021 ; UNEP 2017 ). Here, some of the emerging health issues pertinent to this global problem are briefly described.

Climate change and antimicrobial resistance with corresponding economic costs

Antimicrobial resistance (AMR) is an up-surging complex global health challenge (Garner et al. 2019 ; Lemery et al. 2021 ). Health professionals across the globe are extremely worried due to this phenomenon that has critical potential to reverse almost all the progress that has been achieved so far in the health discipline (Gosling and Arnell 2016 ). A massive amount of antibiotics is produced by many pharmaceutical industries worldwide, and the pathogenic microorganisms are gradually developing resistance to them, which can be comprehended how strongly this aspect can shake the foundations of national and global economies (UNEP 2017 ). This statement is supported by the fact that AMR is not developing in a particular region or country. Instead, it is flourishing in every continent of the world (WHO 2018 ). This plague is heavily pushing humanity to the post-antibiotic era, in which currently antibiotic-susceptible pathogens will once again lead to certain endemics and pandemics after being resistant(WHO 2018 ). Undesirably, if this statement would become a factuality, there might emerge certain risks in undertaking sophisticated interventions such as chemotherapy, joint replacement cases, and organ transplantation (Su et al. 2018 ). Presently, the amplification of drug resistance cases has made common illnesses like pneumonia, post-surgical infections, HIV/AIDS, tuberculosis, malaria, etc., too difficult and costly to be treated or cure well (WHO 2018 ). From a simple example, it can be assumed how easily antibiotic-resistant strains can be transmitted from one person to another and ultimately travel across the boundaries (Berendonk et al. 2015 ). Talking about the second- and third-generation classes of antibiotics, e.g., most renowned generations of cephalosporin antibiotics that are more expensive, broad-spectrum, more toxic, and usually require more extended periods whenever prescribed to patients (Lemery et al. 2021 ; Pärnänen et al. 2019 ). This scenario has also revealed that the abundance of resistant strains of pathogens was also higher in the Southern part (WHO 2018 ). As southern parts are generally warmer than their counterparts, it is evident from this example how CC-induced global warming can augment the spread of antibiotic-resistant strains within the biosphere, eventually putting additional economic burden in the face of developing new and costlier antibiotics. The ARG exchange to susceptible bacteria through one of the potential mechanisms, transformation, transduction, and conjugation; Selection pressure can be caused by certain antibiotics, metals or pesticides, etc., as shown in Fig.  5 .

A typical interaction between the susceptible and resistant strains.

Source: Elsayed et al. ( 2021 ); Karkman et al. ( 2018 )

Certain studies highlighted that conventional urban wastewater treatment plants are typical hotspots where most bacterial strains exchange genetic material through horizontal gene transfer (Fig.  5 ). Although at present, the extent of risks associated with the antibiotic resistance found in wastewater is complicated; environmental scientists and engineers have particular concerns about the potential impacts of these antibiotic resistance genes on human health (Ashbolt 2015 ). At most undesirable and worst case, these antibiotic-resistant genes containing bacteria can make their way to enter into the environment (Pruden et al. 2013 ), irrigation water used for crops and public water supplies and ultimately become a part of food chains and food webs (Ma et al. 2019 ; D. Wu et al. 2019 ). This problem has been reported manifold in several countries (Hendriksen et al. 2019 ), where wastewater as a means of irrigated water is quite common.

Climate change and vector borne-diseases

Temperature is a fundamental factor for the sustenance of living entities regardless of an ecosystem. So, a specific living being, especially a pathogen, requires a sophisticated temperature range to exist on earth. The second essential component of CC is precipitation, which also impacts numerous infectious agents’ transport and dissemination patterns. Global rising temperature is a significant cause of many species extinction. On the one hand, this changing environmental temperature may be causing species extinction, and on the other, this warming temperature might favor the thriving of some new organisms. Here, it was evident that some pathogens may also upraise once non-evident or reported (Patz et al. 2000 ). This concept can be exemplified through certain pathogenic strains of microorganisms that how the likelihood of various diseases increases in response to climate warming-induced environmental changes (Table ​ (Table2 2 ).

Examples of how various environmental changes affect various infectious diseases in humans

Environmental modifications	Potential diseases	The causative organisms and pathway of effect
Construction of canals, dams, irrigation pathways	Schistosomiasis	Snail host locale, human contact
	Malaria	Upbringing places for mosquitoes
	Helminthiases	Larval contact due to moist soil
	River blindness	Blackfly upbringing
Agro-strengthening	Malaria	Crop pesticides
	Venezuelan hemorrhagic fever	Rodent abundance, contact
Suburbanization	Cholera	deprived hygiene, asepsis; augmented water municipal assembling pollution
	Dengue	Water-gathering rubbishes Aedes aegypti mosquito upbringing sites
	Cutaneous leishmaniasis	PSandfly vectors
Deforestation and new tenancy	Malaria	Upbringing sites and trajectories, migration of vulnerable people
	Oropouche	upsurge contact, upbringing of directions
	Visceral leishmaniasis	Recurrent contact with sandfly vectors
Agriculture	Lyme disease	Tick hosts, outside revelation
Ocean heating	Red tide	Poisonous algal blooms

Source: Aron and Patz ( 2001 )

A recent example is an outburst of coronavirus (COVID-19) in the Republic of China, causing pneumonia and severe acute respiratory complications (Cui et al. 2021 ; Song et al. 2021 ). The large family of viruses is harbored in numerous animals, bats, and snakes in particular (livescience.com) with the subsequent transfer into human beings. Hence, it is worth noting that the thriving of numerous vectors involved in spreading various diseases is influenced by Climate change (Ogden 2018 ; Santos et al. 2021 ).

Psychological impacts of climate change

Climate change (CC) is responsible for the rapid dissemination and exaggeration of certain epidemics and pandemics. In addition to the vast apparent impacts of climate change on health, forestry, agriculture, etc., it may also have psychological implications on vulnerable societies. It can be exemplified through the recent outburst of (COVID-19) in various countries around the world (Pal 2021 ). Besides, the victims of this viral infection have made healthy beings scarier and terrified. In the wake of such epidemics, people with common colds or fever are also frightened and must pass specific regulatory protocols. Living in such situations continuously terrifies the public and makes the stress familiar, which eventually makes them psychologically weak (npr.org).

CC boosts the extent of anxiety, distress, and other issues in public, pushing them to develop various mental-related problems. Besides, frequent exposure to extreme climatic catastrophes such as geological disasters also imprints post-traumatic disorder, and their ubiquitous occurrence paves the way to developing chronic psychological dysfunction. Moreover, repetitive listening from media also causes an increase in the person’s stress level (Association 2020 ). Similarly, communities living in flood-prone areas constantly live in extreme fear of drowning and die by floods. In addition to human lives, the flood-induced destruction of physical infrastructure is a specific reason for putting pressure on these communities (Ogden 2018 ). For instance, Ogden ( 2018 ) comprehensively denoted that Katrina’s Hurricane augmented the mental health issues in the victim communities.

Climate change impacts on the forestry sector

Forests are the global regulators of the world’s climate (FAO 2018 ) and have an indispensable role in regulating global carbon and nitrogen cycles (Rehman et al. 2021 ; Reichstein and Carvalhais 2019 ). Hence, disturbances in forest ecology affect the micro and macro-climates (Ellison et al. 2017 ). Climate warming, in return, has profound impacts on the growth and productivity of transboundary forests by influencing the temperature and precipitation patterns, etc. As CC induces specific changes in the typical structure and functions of ecosystems (Zhang et al. 2017 ) as well impacts forest health, climate change also has several devastating consequences such as forest fires, droughts, pest outbreaks (EPA 2018 ), and last but not the least is the livelihoods of forest-dependent communities. The rising frequency and intensity of another CC product, i.e., droughts, pose plenty of challenges to the well-being of global forests (Diffenbaugh et al. 2017 ), which is further projected to increase soon (Hartmann et al. 2018 ; Lehner et al. 2017 ; Rehman et al. 2021 ). Hence, CC induces storms, with more significant impacts also put extra pressure on the survival of the global forests (Martínez-Alvarado et al. 2018 ), significantly since their influences are augmented during higher winter precipitations with corresponding wetter soils causing weak root anchorage of trees (Brázdil et al. 2018 ). Surging temperature regimes causes alterations in usual precipitation patterns, which is a significant hurdle for the survival of temperate forests (Allen et al. 2010 ; Flannigan et al. 2013 ), letting them encounter severe stress and disturbances which adversely affects the local tree species (Hubbart et al. 2016 ; Millar and Stephenson 2015 ; Rehman et al. 2021 ).

Climate change impacts on forest-dependent communities

Forests are the fundamental livelihood resource for about 1.6 billion people worldwide; out of them, 350 million are distinguished with relatively higher reliance (Bank 2008 ). Agro-forestry-dependent communities comprise 1.2 billion, and 60 million indigenous people solely rely on forests and their products to sustain their lives (Sunderlin et al. 2005 ). For example, in the entire African continent, more than 2/3rd of inhabitants depend on forest resources and woodlands for their alimonies, e.g., food, fuelwood and grazing (Wasiq and Ahmad 2004 ). The livings of these people are more intensely affected by the climatic disruptions making their lives harder (Brown et al. 2014 ). On the one hand, forest communities are incredibly vulnerable to CC due to their livelihoods, cultural and spiritual ties as well as socio-ecological connections, and on the other, they are not familiar with the term “climate change.” (Rahman and Alam 2016 ). Among the destructive impacts of temperature and rainfall, disruption of the agroforestry crops with resultant downscale growth and yield (Macchi et al. 2008 ). Cruz ( 2015 ) ascribed that forest-dependent smallholder farmers in the Philippines face the enigma of delayed fruiting, more severe damages by insect and pest incidences due to unfavorable temperature regimes, and changed rainfall patterns.

Among these series of challenges to forest communities, their well-being is also distinctly vulnerable to CC. Though the detailed climate change impacts on human health have been comprehensively mentioned in the previous section, some studies have listed a few more devastating effects on the prosperity of forest-dependent communities. For instance, the Himalayan people have been experiencing frequent skin-borne diseases such as malaria and other skin diseases due to increasing mosquitoes, wild boar as well, and new wasps species, particularly in higher altitudes that were almost non-existent before last 5–10 years (Xu et al. 2008 ). Similarly, people living at high altitudes in Bangladesh have experienced frequent mosquito-borne calamities (Fardous; Sharma 2012 ). In addition, the pace of other waterborne diseases such as infectious diarrhea, cholera, pathogenic induced abdominal complications and dengue has also been boosted in other distinguished regions of Bangladesh (Cell 2009 ; Gunter et al. 2008 ).

Pest outbreak

Upscaling hotter climate may positively affect the mobile organisms with shorter generation times because they can scurry from harsh conditions than the immobile species (Fettig et al. 2013 ; Schoene and Bernier 2012 ) and are also relatively more capable of adapting to new environments (Jactel et al. 2019 ). It reveals that insects adapt quickly to global warming due to their mobility advantages. Due to past outbreaks, the trees (forests) are relatively more susceptible victims (Kurz et al. 2008 ). Before CC, the influence of factors mentioned earlier, i.e., droughts and storms, was existent and made the forests susceptible to insect pest interventions; however, the global forests remain steadfast, assiduous, and green (Jactel et al. 2019 ). The typical reasons could be the insect herbivores were regulated by several tree defenses and pressures of predation (Wilkinson and Sherratt 2016 ). As climate greatly influences these phenomena, the global forests cannot be so sedulous against such challenges (Jactel et al. 2019 ). Table ​ Table3 3 demonstrates some of the particular considerations with practical examples that are essential while mitigating the impacts of CC in the forestry sector.

Essential considerations while mitigating the climate change impacts on the forestry sector

Attributes		Description	Forestry example
Purposefulness	Autonomous	Includes continuing application of prevailing information and techniques in retort to experienced climate change	Thin to reduce drought stress; construct breaks in vegetation to Stop feast of wildfires, vermin, and ailments
Timing	Preemptive	Necessitates interactive change to diminish future injury, jeopardy, and weakness, often through planning, observing, growing consciousness, structure partnerships, and ornamental erudition or investigation	Ensure forest property against potential future losses; transition to species or stand erections that are better reformed to predictable future conditions; trial with new forestry organization practices
Scope	Incremental	Involves making small changes in present circumstances to circumvent disturbances and ongoing to chase the same purposes	Condense rotation pauses to decrease the likelihood of harm to storm Events, differentiate classes to blowout jeopardy; thin to lessening compactness and defenselessness of jungle stands to tension
Goal	Opposition	Shield or defend from alteration; take procedures to reservation constancy and battle change	Generate refugia for rare classes; defend woodlands from austere fire and wind uproar; alter forest construction to reduce harshness or extent of wind and ice impairment; establish breaks in vegetation to dampen the spread of vermin, ailments, and wildfire

Source : Fischer ( 2019 )

Climate change impacts on tourism

Tourism is a commercial activity that has roots in multi-dimensions and an efficient tool with adequate job generation potential, revenue creation, earning of spectacular foreign exchange, enhancement in cross-cultural promulgation and cooperation, a business tool for entrepreneurs and eventually for the country’s national development (Arshad et al. 2018 ; Scott 2021 ). Among a plethora of other disciplines, the tourism industry is also a distinct victim of climate warming (Gössling et al. 2012 ; Hall et al. 2015 ) as the climate is among the essential resources that enable tourism in particular regions as most preferred locations. Different places at different times of the year attract tourists both within and across the countries depending upon the feasibility and compatibility of particular weather patterns. Hence, the massive variations in these weather patterns resulting from CC will eventually lead to monumental challenges to the local economy in that specific area’s particular and national economy (Bujosa et al. 2015 ). For instance, the Intergovernmental Panel on Climate Change (IPCC) report demonstrated that the global tourism industry had faced a considerable decline in the duration of ski season, including the loss of some ski areas and the dramatic shifts in tourist destinations’ climate warming.

Furthermore, different studies (Neuvonen et al. 2015 ; Scott et al. 2004 ) indicated that various currently perfect tourist spots, e.g., coastal areas, splendid islands, and ski resorts, will suffer consequences of CC. It is also worth noting that the quality and potential of administrative management potential to cope with the influence of CC on the tourism industry is of crucial significance, which renders specific strengths of resiliency to numerous destinations to withstand against it (Füssel and Hildén 2014 ). Similarly, in the partial or complete absence of adequate socio-economic and socio-political capital, the high-demanding tourist sites scurry towards the verge of vulnerability. The susceptibility of tourism is based on different components such as the extent of exposure, sensitivity, life-supporting sectors, and capacity assessment factors (Füssel and Hildén 2014 ). It is obvious corporality that sectors such as health, food, ecosystems, human habitat, infrastructure, water availability, and the accessibility of a particular region are prone to CC. Henceforth, the sensitivity of these critical sectors to CC and, in return, the adaptive measures are a hallmark in determining the composite vulnerability of climate warming (Ionescu et al. 2009 ).

Moreover, the dependence on imported food items, poor hygienic conditions, and inadequate health professionals are dominant aspects affecting the local terrestrial and aquatic biodiversity. Meanwhile, the greater dependency on ecosystem services and its products also makes a destination more fragile to become a prey of CC (Rizvi et al. 2015 ). Some significant non-climatic factors are important indicators of a particular ecosystem’s typical health and functioning, e.g., resource richness and abundance portray the picture of ecosystem stability. Similarly, the species abundance is also a productive tool that ensures that the ecosystem has a higher buffering capacity, which is terrific in terms of resiliency (Roscher et al. 2013 ).

Climate change impacts on the economic sector

Climate plays a significant role in overall productivity and economic growth. Due to its increasingly global existence and its effect on economic growth, CC has become one of the major concerns of both local and international environmental policymakers (Ferreira et al. 2020 ; Gleditsch 2021 ; Abbass et al. 2021b ; Lamperti et al. 2021 ). The adverse effects of CC on the overall productivity factor of the agricultural sector are therefore significant for understanding the creation of local adaptation policies and the composition of productive climate policy contracts. Previous studies on CC in the world have already forecasted its effects on the agricultural sector. Researchers have found that global CC will impact the agricultural sector in different world regions. The study of the impacts of CC on various agrarian activities in other demographic areas and the development of relative strategies to respond to effects has become a focal point for researchers (Chandioet al. 2020 ; Gleditsch 2021 ; Mosavi et al. 2020 ).

With the rapid growth of global warming since the 1980s, the temperature has started increasing globally, which resulted in the incredible transformation of rain and evaporation in the countries. The agricultural development of many countries has been reliant, delicate, and susceptible to CC for a long time, and it is on the development of agriculture total factor productivity (ATFP) influence different crops and yields of farmers (Alhassan 2021 ; Wu  2020 ).

Food security and natural disasters are increasing rapidly in the world. Several major climatic/natural disasters have impacted local crop production in the countries concerned. The effects of these natural disasters have been poorly controlled by the development of the economies and populations and may affect human life as well. One example is China, which is among the world’s most affected countries, vulnerable to natural disasters due to its large population, harsh environmental conditions, rapid CC, low environmental stability, and disaster power. According to the January 2016 statistical survey, China experienced an economic loss of 298.3 billion Yuan, and about 137 million Chinese people were severely affected by various natural disasters (Xie et al. 2018 ).

Mitigation and adaptation strategies of climate changes

Adaptation and mitigation are the crucial factors to address the response to CC (Jahanzad et al. 2020 ). Researchers define mitigation on climate changes, and on the other hand, adaptation directly impacts climate changes like floods. To some extent, mitigation reduces or moderates greenhouse gas emission, and it becomes a critical issue both economically and environmentally (Botzen et al. 2021 ; Jahanzad et al. 2020 ; Kongsager 2018 ; Smit et al. 2000 ; Vale et al. 2021 ; Usman et al. 2021 ; Verheyen 2005 ).

Researchers have deep concern about the adaptation and mitigation methodologies in sectoral and geographical contexts. Agriculture, industry, forestry, transport, and land use are the main sectors to adapt and mitigate policies(Kärkkäinen et al. 2020 ; Waheed et al. 2021 ). Adaptation and mitigation require particular concern both at the national and international levels. The world has faced a significant problem of climate change in the last decades, and adaptation to these effects is compulsory for economic and social development. To adapt and mitigate against CC, one should develop policies and strategies at the international level (Hussain et al. 2020 ). Figure  6 depicts the list of current studies on sectoral impacts of CC with adaptation and mitigation measures globally.

Sectoral impacts of climate change with adaptation and mitigation measures.

Conclusion and future perspectives

Specific socio-agricultural, socio-economic, and physical systems are the cornerstone of psychological well-being, and the alteration in these systems by CC will have disastrous impacts. Climate variability, alongside other anthropogenic and natural stressors, influences human and environmental health sustainability. Food security is another concerning scenario that may lead to compromised food quality, higher food prices, and inadequate food distribution systems. Global forests are challenged by different climatic factors such as storms, droughts, flash floods, and intense precipitation. On the other hand, their anthropogenic wiping is aggrandizing their existence. Undoubtedly, the vulnerability scale of the world’s regions differs; however, appropriate mitigation and adaptation measures can aid the decision-making bodies in developing effective policies to tackle its impacts. Presently, modern life on earth has tailored to consistent climatic patterns, and accordingly, adapting to such considerable variations is of paramount importance. Because the faster changes in climate will make it harder to survive and adjust, this globally-raising enigma calls for immediate attention at every scale ranging from elementary community level to international level. Still, much effort, research, and dedication are required, which is the most critical time. Some policy implications can help us to mitigate the consequences of climate change, especially the most affected sectors like the agriculture sector;

Warming might lengthen the season in frost-prone growing regions (temperate and arctic zones), allowing for longer-maturing seasonal cultivars with better yields (Pfadenhauer 2020 ; Bonacci 2019 ). Extending the planting season may allow additional crops each year; when warming leads to frequent warmer months highs over critical thresholds, a split season with a brief summer fallow may be conceivable for short-period crops such as wheat barley, cereals, and many other vegetable crops. The capacity to prolong the planting season in tropical and subtropical places where the harvest season is constrained by precipitation or agriculture farming occurs after the year may be more limited and dependent on how precipitation patterns vary (Wu et al. 2017 ).

The genetic component is comprehensive for many yields, but it is restricted like kiwi fruit for a few. Ali et al. ( 2017 ) investigated how new crops will react to climatic changes (also stated in Mall et al. 2017 ). Hot temperature, drought, insect resistance; salt tolerance; and overall crop production and product quality increases would all be advantageous (Akkari 2016 ). Genetic mapping and engineering can introduce a greater spectrum of features. The adoption of genetically altered cultivars has been slowed, particularly in the early forecasts owing to the complexity in ensuring features are expediently expressed throughout the entire plant, customer concerns, economic profitability, and regulatory impediments (Wirehn 2018 ; Davidson et al. 2016 ).

To get the full benefit of the CO 2 would certainly require additional nitrogen and other fertilizers. Nitrogen not consumed by the plants may be excreted into groundwater, discharged into water surface, or emitted from the land, soil nitrous oxide when large doses of fertilizer are sprayed. Increased nitrogen levels in groundwater sources have been related to human chronic illnesses and impact marine ecosystems. Cultivation, grain drying, and other field activities have all been examined in depth in the studies (Barua et al. 2018 ).

• The technological and socio-economic adaptation

The policy consequence of the causative conclusion is that as a source of alternative energy, biofuel production is one of the routes that explain oil price volatility separate from international macroeconomic factors. Even though biofuel production has just begun in a few sample nations, there is still a tremendous worldwide need for feedstock to satisfy industrial expansion in China and the USA, which explains the food price relationship to the global oil price. Essentially, oil-exporting countries may create incentives in their economies to increase food production. It may accomplish by giving farmers financing, seedlings, fertilizers, and farming equipment. Because of the declining global oil price and, as a result, their earnings from oil export, oil-producing nations may be unable to subsidize food imports even in the near term. As a result, these countries can boost the agricultural value chain for export. It may be accomplished through R&D and adding value to their food products to increase income by correcting exchange rate misalignment and adverse trade terms. These nations may also diversify their economies away from oil, as dependence on oil exports alone is no longer economically viable given the extreme volatility of global oil prices. Finally, resource-rich and oil-exporting countries can convert to non-food renewable energy sources such as solar, hydro, coal, wind, wave, and tidal energy. By doing so, both world food and oil supplies would be maintained rather than harmed.

IRENA’s modeling work shows that, if a comprehensive policy framework is in place, efforts toward decarbonizing the energy future will benefit economic activity, jobs (outweighing losses in the fossil fuel industry), and welfare. Countries with weak domestic supply chains and a large reliance on fossil fuel income, in particular, must undertake structural reforms to capitalize on the opportunities inherent in the energy transition. Governments continue to give major policy assistance to extract fossil fuels, including tax incentives, financing, direct infrastructure expenditures, exemptions from environmental regulations, and other measures. The majority of major oil and gas producing countries intend to increase output. Some countries intend to cut coal output, while others plan to maintain or expand it. While some nations are beginning to explore and execute policies aimed at a just and equitable transition away from fossil fuel production, these efforts have yet to impact major producing countries’ plans and goals. Verifiable and comparable data on fossil fuel output and assistance from governments and industries are critical to closing the production gap. Governments could increase openness by declaring their production intentions in their climate obligations under the Paris Agreement.

It is firmly believed that achieving the Paris Agreement commitments is doubtlful without undergoing renewable energy transition across the globe (Murshed 2020 ; Zhao et al. 2022 ). Policy instruments play the most important role in determining the degree of investment in renewable energy technology. This study examines the efficacy of various policy strategies in the renewable energy industry of multiple nations. Although its impact is more visible in established renewable energy markets, a renewable portfolio standard is also a useful policy instrument. The cost of producing renewable energy is still greater than other traditional energy sources. Furthermore, government incentives in the R&D sector can foster innovation in this field, resulting in cost reductions in the renewable energy industry. These nations may export their technologies and share their policy experiences by forming networks among their renewable energy-focused organizations. All policy measures aim to reduce production costs while increasing the proportion of renewables to a country’s energy system. Meanwhile, long-term contracts with renewable energy providers, government commitment and control, and the establishment of long-term goals can assist developing nations in deploying renewable energy technology in their energy sector.

Author contribution

KA: Writing the original manuscript, data collection, data analysis, Study design, Formal analysis, Visualization, Revised draft, Writing-review, and editing. MZQ: Writing the original manuscript, data collection, data analysis, Writing-review, and editing. HS: Contribution to the contextualization of the theme, Conceptualization, Validation, Supervision, literature review, Revised drapt, and writing review and editing. MM: Writing review and editing, compiling the literature review, language editing. HM: Writing review and editing, compiling the literature review, language editing. IY: Contribution to the contextualization of the theme, literature review, and writing review and editing.

Availability of data and material

Declarations.

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The authors declare no competing interests.

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Contributor Information

Kashif Abbass, Email: nc.ude.tsujn@ssabbafihsak .

Muhammad Zeeshan Qasim, Email: moc.kooltuo@888misaqnahseez .

Huaming Song, Email: nc.ude.tsujn@gnimauh .

Muntasir Murshed, Email: [email protected] .

Haider Mahmood, Email: moc.liamtoh@doomhamrediah .

Ijaz Younis, Email: nc.ude.tsujn@sinuoyzaji .

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Frequently Asked Questions

General questions

What’s the difference between climate change and global warming.

“Global warming” refers to the long-term warming of the planet. “Climate change” encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.

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What’s the difference between weather and climate?

“Weather” refers to the more local changes in the climate we see around us, on short timescales from minutes to hours, to days to weeks. Examples are familiar – rain, snow, clouds, winds, thunderstorms, sleet, and hail.

“Climate” refers to longer-term averages (which may be regional or global) and can be thought of as the weather averaged over several decades.

Is it too late to prevent climate change?

Humans have caused major climate changes to happen already, and we have set in motion more changes still. However, if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries.

Do scientists agree on climate change?

Yes, the vast majority of actively publishing climate scientists – 97 percent – agree that humans are causing global warming and climate change.

What is NASA's role in climate research?

NASA’s role is to make observations of our Earth's systems (geosphere, biosphere, cryosphere, hydrosphere, and atmosphere)--and how they connect--that can be used by the public, researchers, policymakers and to support strategic decision-making. The core responsibility of NASA is to conduct rigorous scientific research. It's important to clarify that NASA does not advocate for specific climate policies.

Climate data

What types of data do scientists use to study climate.

Climate researchers employ a wide range of direct and indirect measurements to thoroughly investigate Earth's climate history. These measurements include data from natural sources like tree rings, ice cores, corals, and sediments from oceans and lakes. Additionally, data from satellites in space, instruments on the International Space Station, aircraft, ships, buoys, and ground-based instruments are all vital for this research. This comprehensive array of data sources allows scientists to gain a detailed understanding of Earth's climate history.

How do scientists measure global temperature?

Modern weather observations primarily originate from a network of sources, including weather stations , weather balloons, radar systems, ships, buoys, and satellites.

Can scientists use global temperature data as is?

No. The Goddard Institute for Space Studies (GISS) utilizes temperature data for conducting long-term climate studies. To ensure the reliability of station data for such research, it's crucial that the time series of observations are consistent. We need to eliminate any temperature fluctuations that are not caused by climate-related factors. These fluctuations can occur due to station relocations, equipment upgrades, or the merging of data from various sources into a single dataset.

Once the invalid data are eliminated, are global temperature data ready to use?

Not yet. In order to use temperature data effectively, we have to make adjustments to account for all the changes that have occurred over the past 100-150 years. 

How do scientists deal with changes in where data come from?

Major climate research organizations worldwide have developed mathematically rigorous, peer-reviewed data-processing methods to identify and compensate for changes in observing conditions.

How do scientists know their data-processing techniques are reliable?

The global temperature records calculated by U.S. and other countries are remarkably similar, even though they use different methods to process the data. NASA's Goddard Institute for Space Studies (GISS), National Climatic Data Center (NCDC), and other respected groups subject their techniques and processed data to extensive peer-reviewed analyses.

Does data processing make temperature data warmer?

Almost half of the National Oceanic and Atmospheric Administration's (NOAA) corrected data are cooler than the original records. NOAA's corrections of temperatures over the oceans — done to compensate for changes in methods of observing the temperature of water at the surface of the ocean — reduced the warming trend in global temperature.

Does data processing destroy the original data?

No, the original records are preserved and are available at no cost online. You can access the National Climatic Data Center's (NCDC) U.S. and global records here .

Greenhouse gases

What is the greenhouse effect.

The greenhouse effect is the process through which heat is trapped near Earth's surface by substances known as 'greenhouse gases.' Imagine these gases as a cozy blanket enveloping our planet, helping to maintain a warmer temperature than it would have otherwise. Greenhouse gases consist of carbon dioxide, methane, ozone, nitrous oxide, chlorofluorocarbons, and water vapor. Water vapor, which reacts to temperature changes, is referred to as a 'feedback', because it amplifies the effect of forces that initially caused the warming.

How might Earth’s atmosphere, land, and ocean systems respond to changes in carbon dioxide over time?

The amount of anthropogenic carbon dioxide (CO 2 ) absorbed by Earth's life forms, ocean, and other "sinks" might decrease as time goes by. Natural carbon sinks (the carbon absorbers, as opposed to "sources," which release carbon) on land and in the ocean have become less effective over time. That is, natural sinks that removed about 60% of annual human-caused CO 2 emissions in 1959 now remove about 55% today.

Which is a bigger methane source: cow belching or cow flatulence?

Contrary to common belief, it's actually cow belching caused by a process called enteric fermentation that contributes to methane emissions.

Can new NASA carbon-to-oxygen conversion technology like MOXIE be used to address climate change?

Since MOXIE works by ingesting carbon dioxide – the gas that’s mostly driving climate change here on Earth – and produces oxygen, a lot of people wondered whether it could it be helpful on our own planet. But while technology is part of any plan for addressing climate change, the conversion that MOXIE accomplished on Mars is not a viable approach.

Global temperatures (land and ocean)

Why does the temperature record shown on your "vital signs" page begin at 1880.

Three of the world’s most complete temperature tracking records, maintained by NASA’s Goddard Institute for Space Studies, the National Oceanic and Atmospheric Administration’s National Climactic Data Center and the UK Meteorological Office’s Hadley Centre, begin in 1880. The oldest continuous temperature record is the Central England Temperature Data Series, which began in 1659, and the Hadley Centre has some measurements beginning in 1850, but there are too few data before 1880 for scientists to estimate average temperatures for the entire planet.

Has Earth continued to warm since 1998?

Yes, evidence shows warming from 1998 to the present, with 2014, 2015, 2016, 2017, 2018, 2019, and 2020 being the hottest years globally since 1880.

Which measurement is more accurate: taking Earth’s surface temperature from the ground or from space?

Satellites technically do not measure either temperature or the surface (where people live). Therefore, it's safe to say that ground thermometers are more accurate than satellite measurements.

Is the ocean continuing to warm?

Yes, the ocean is continuing to warm. Notably, all ocean basins have been experiencing significant warming since 1998, with more heat being transferred deeper into the ocean since 1990.

Can you explain the urban heat island effect?

While urban areas are warmer than surrounding rural areas, the urban heat island effect has had little to no impact on our warming world because scientists have accounted for it in their measurements.

Ice and snow

Are the land-based ice sheets in greenland and antarctica continuing to lose mass (ice).

Data from NASA's GRACE satellites, which measured Earth’s gravity field, show that the land ice sheets in both Antarctica and Greenland have been losing mass (ice) since 2002.

How are Earth’s mountain glaciers faring in a warming world?

On average, most of Earth’s mountain glaciers are continuing to melt.

How is Earth’s sea ice faring in our warming world?

Arctic sea ice volume and extent have been declining since record-keeping began in the late 1970s and prior. Antarctic sea ice extent is currently below the long-term average of prior decades since 1979 .

What’s the difference between glacier or ice sheet surface mass balance and total mass balance?

Surface mass balance is the difference between the precipitation (rain and snow) that has accumulated on the upper surfaces of glaciers and ice sheets and what has been lost due to melt, eventual runoff, and evaporation.Total mass balance is the difference between total mass gains and total mass losses, which includes ice lost in the lower margins due to calving and thinning from contact with warm ocean waters.

If all of Earth's ice melts and flows into the ocean, what would happen to the planet's rotation?

Melting land ice, like mountain glaciers and the Greenland and Antarctic ice sheets, will change Earth’s rotation only if the meltwater flows into the ocean. For example, if the Greenland ice sheet were to completely melt and the meltwater were to completely flow into the ocean, then global sea level would rise by about seven meters (23 feet) and Earth would rotate more slowly, with the length of the day becoming longer than it is today, by about 2 milliseconds.Melting sea ice, such as the Arctic ice cap, does not change sea level because the ice displaces its volume and, hence, does not change Earth’s rotation.

The sun, volcanoes, and more

Is the sun causing global warming.

No. The Sun can influence Earth’s climate, but it isn’t responsible for the warming trend we’ve seen in recent decades.

What happens if the next solar cycle becomes less active? Will we enter into a new ice age?

No. Even if the amount of radiation coming from the Sun were to decrease as it has before, it would not significantly affect the global warming coming from long-lived, human-emitted greenhouse gases. Further, given our greenhouse gas emissions to date and those expected to come, the evidence points to the next “ice age” being averted altogether.

What do volcanoes have to do with climate change?

Volcanic eruptions are often discussed in the context of climate change because they release CO2 and other gases into our atmosphere. However, the impact of human activities on the carbon cycle far exceeds that of all the world's volcanoes combined, by more than 100 times.To put it in perspective, while volcanic eruptions do contribute to an increase in atmospheric CO2, human activities release an amount of CO2 equivalent to what a Mount St. Helens-sized eruption produces every 2.5 hours and a Mount Pinatubo-sized eruption twice daily.

Is the ozone hole causing climate change?

Yes and no. The ozone hole is not causing global warming, but it is affecting atmospheric circulation.

The amount of carbon dioxide in the atmosphere is measured at Mauna Loa, Hawaii, by the National Oceanic and Atmospheric Administration. Could the rising carbon dioxide be caused by the volcano?

The amount of carbon dioxide (CO 2 ) in the atmosphere is measured by many different methods, all around the world. By using more than one approach, scientists can be sure they’re measuring a global trend, rather than a local variation.

Do small particles in the air (aerosols) have a warming or cooling effect on the climate?

Both! In general, light-colored particles in the atmosphere will reflect incoming sunlight and cause a cooling effect. Dark-colored particles absorb sunlight and make the atmosphere warmer. Because different types of particles have different effects, aerosols are a hot topic in climate research.

Past climates

How do we know what greenhouse gas and temperature levels were in the distant past.

Ice cores are scientists’ best source for historical climate data. Other tools for learning about Earth’s ancient atmosphere include growth rings in trees, which keep a rough record of each growing season’s temperature, moisture and cloudiness going back about 2,000 years. Corals also form growth rings that provide information about temperature and nutrients in the tropical ocean. Other proxies, such as benthic cores, extend our knowledge of past climate back about a billion years.

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Frequently Asked Questions About Climate Change

Below are answers to some frequently asked questions about climate change. For information about evidence of climate change, the greenhouse effect, and the human role in climate change, please see EPA Climate Science .

On this page:

What is the difference between weather and climate?

What is climate change, what is the difference between global warming and climate change, what is the difference between climate change and climate variability, why has my town experienced record-breaking cold and snowfall if the climate is warming, is there scientific consensus that people are causing today’s climate change, do natural variations in climate contribute to today’s climate change, why be concerned about a degree or two change in the average global temperature, how does climate change affect people’s health, who is most at risk from the impacts of climate change, how can people reduce the risks of climate change, what are the benefits of taking action now.

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"Weather" refers to the day-to-day state of the atmosphere such as the combination of temperature, humidity, rainfall, wind, and other factors. "Climate" describes the weather of a place averaged over a period of time, often 30 years. Think about it this way: climate is something that can be expected to happen in general, like a cold winter season, whereas weather is what a person might experience on any given day, like a snowstorm in January or a sunny day in July.

Climate change involves significant changes in average conditions—such as temperature, precipitation, wind patterns, and other aspects of climate—that occur over years, decades, centuries, or longer. Climate change involves longer-term trends, such as shifts toward warmer, wetter, or drier conditions. These trends can be caused by natural variability in climate over time, as well as human activities that add greenhouse gases to the atmosphere like burning fossil fuels for energy.

The terms "global warming" and "climate change" are sometimes used interchangeably, but global warming is just one of the ways in which climate is affected by rising concentrations of greenhouse gases. "Global warming" describes the recent rise in the global average temperature near the earth's surface, which is caused mostly by increasing concentrations of greenhouse gases (such as carbon dioxide and methane) in the atmosphere from human activities such as burning fossil fuels for energy.

Climate change occurs over a long period of time, typically over decades or longer. In contrast, climate variability includes changes that occur within shorter timeframes, such as a month, season, or year. Climate variability explains the natural variability within the system. For example, one unusually cold or wet year followed by an unusually warm or dry year would not be considered a sign of climate change.

Today’s Climate Change

Even though the planet is warming, some areas may be experiencing extra cold or snowy winters. These cold spells are due to variability in local weather patterns, which sometimes lead to colder-than-average seasons or even colder-than-average years at the local or regional level. In fact, a warmer climate traps more water vapor in the air, which may lead to extra snowy winters in some areas. As long as it is still cold enough to snow, a warming climate can lead to bigger snowstorms.

Yes. Climate scientists overwhelmingly agree that people are contributing significantly to today’s climate change, primarily by releasing excess greenhouse gases into the atmosphere from activities such as burning fossil fuels for energy, cultivating crops, raising livestock, and clearing forests. The Intergovernmental Panel on Climate Change's Sixth Assessment Report , which represents the work of hundreds of leading experts in climate science, states that "it is unequivocal that human influence has warmed the atmosphere, ocean and land. Widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred.”

The 2018 National Climate Assessment , developed by the U.S. Global Change Research Program—which is composed of 13 federal scientific agencies—concluded that scientific evidence consistently points to human activities, rather than natural climate trends, as the “dominant cause” behind the rapid global temperature increase of 1.8°F from 1901 to 2016 (see Figure 1). Hundreds of independent and governmental scientific organizations have released similar statements, both in the United States and worldwide, including the World Meteorological Organization , the American Meteorological Society , and the American Geophysical Union .

The earth does go through natural cycles of warming and cooling caused by factors such as changes in the sun or volcanic activity. For example, there were times in the distant past when the earth was warmer than it is now. However, natural variations in climate do not explain today’s climate change. Most of the warming since 1950 has been caused by human emissions of greenhouse gases that come from a variety of activities, including burning fossil fuels.

A degree or two change in average global temperature might not sound like much to worry about, but relatively small changes in the earth’s average temperature can mean big changes in local and regional climate, creating risks to public health and safety , water resources , agriculture , infrastructure , and ecosystems . Among the many examples cited by the 2018 National Climate Assessment are an increase in heat waves and days with temperatures above 90°F; more extreme weather events such as storms, droughts, and floods; and a projected sea level rise of 1 to 4 feet by the end of this century, which could put certain areas of the country underwater.

Climate change poses many threats to people’s health and well-being. Among the health impacts cited by the 2018 National Climate Assessment are the following:

• Atmospheric warming has the potential to increase ground-level ozone in many regions, which can cause multiple health issues (e.g., bronchitis, emphysema, and asthma) and worsen lung function.
• Higher summer temperatures are linked to an increased risk of heat-related illnesses and death . Older adults, pregnant women, and children are at particular risk, as are people living in urban areas because of the additional heat associated with urban heat islands .
• Climate change is expected to expose more people to ticks that carry Lyme disease or other bacterial and viral agents, and to mosquitoes that transmit West Nile and other viruses.
• More frequent extreme weather events such as droughts , hurricanes , floods , and wildfires will not only put people’s lives at risk, but can also worsen underlying medical conditions, increase stress, and lead to adverse mental health effects.
• Rising temperatures and extreme weather have the potential to disrupt the availability, safety, and nutritional quality of food.

See EPA’s Climate Indicators website for more information about the effects of climate change in the United States.

Everyone will be affected by climate change, but some people may be more affected than others. Among the most vulnerable people are those in overburdened, underserved, and economically distressed communities. Three key factors influence a person’s vulnerability to the impacts of climate change:

• Exposure . Some people are more at risk simply because they are more exposed to climate change hazards where they live or work. For example, people who live on the coast can be more vulnerable to sea level rise, coastal storms, and flooding.
• Sensitivity . Some people are more sensitive to the impacts of climate change, such as children, pregnant women, and those with pre-existing medical conditions such as asthma.
• Adaptability . Older adults, those with disabilities, those with low income, and some indigenous people may have more difficulty than others in adapting to climate change hazards.

In addition, there is a wide range of other factors that influence people’s vulnerability. For example, people with less access to healthcare, adequate housing, and financial resources are less likely to rebound from climate disasters. People who are excluded from planning processes, experience racial and ethnic discrimination, or have language barriers are also more vulnerable to and less able to prepare for and avoid the risks of climate change.

Learn more about the connections between climate change and human health .

People can reduce the risks of climate change by making choices that reduce greenhouse gas emissions and by preparing for the changes expected in the future. Decisions that people make today will shape the world for decades and even centuries to come. Communities can also prepare for the changes in the decades ahead by identifying and reducing their vulnerabilities and considering climate change risks in planning and development . Such actions can ensure that the most vulnerable populations —such as young children, older adults, and people living in poverty—are protected from the health and safety threats of climate change.

The longer people wait to act on climate change, the more damaging its effects will become on the planet and people’s health. If people fail to take action soon, more drastic and costly measures to prevent greenhouse gases from exceeding dangerous levels could be needed later. The most recent National Climate Assessment found that global efforts to reduce greenhouse gas emissions could avoid tens of thousands of deaths per year in the United States by the end of the century, as well as billions of dollars in damages related to water shortages, wildfires, agricultural losses, flooding, and other impacts. There are many actions that people can take now to help reduce the risk of climate change while also improving the natural environment, community infrastructure and transportation systems, and overall health.

• Frequently Asked Questions

5 ways NOAA scientists are answering big questions about climate change

• April 20, 2021
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From warmer ocean temperatures to longer and more intense droughts and heat waves, climate change is affecting our entire planet. Scientists at NOAA have long worked to track, understand and predict how climate change is progressing and impacting ecosystems, communities and economies. This Earth Day, take a look at five ways scientists are studying this far-reaching global trend.

1. Tracking greenhouse gas levels in the atmosphere

To understand climate change, scientists need an accurate, up-to-date record of how greenhouse gas levels in the atmosphere have changed over time. Enter: NOAA Global Monitoring Laboratories’ Global Greenhouse Gas Reference Network , which measures the three main long-term drivers of climate change: carbon dioxide (CO2), methane, and nitrous oxide. Four remote atmospheric baseline observatories form the backbone of the monitoring system – the most well-known of which, located in Mauna Loa, Hawaii, is home to the longest record of direct measurements of CO2 in the atmosphere. This year, scientists used data from these observatories to confirm that average global CO2 levels had surged in 2020 to 412.5 parts per million – levels that are higher than at any time in the past 3.6 million years.

2. Understanding ocean warming 

The ocean can absorb and store a lot of heat. In fact, more than 90 percent of the planet’s warming over the past 50 years has occurred in the ocean, making the buoys, floats and other ocean monitoring tools NOAA uses to keep tabs on ocean warming critical. Argo, for instance, is a network of about 4,000 autonomous floats that drift throughout the ocean, gathering critical data on salt content and temperature. Last year, data collected by Argo floats helped scientists determine that the area of ocean regions with long-term warming trends dwarfs that of regions with cooling trends. Deep Argo floats have also found that the coldest waters off of Antarctica are warming three times faster than they were in the 1990s. Tracking ocean warming helps scientists better predict sea level rise, gauge threats to coral reef ecosystems and important fisheries, and build knowledge on how a warmer ocean impacts our weather – including severe weather like hurricanes.  

3. Exploring the link between climate change and hurricanes

Hurricanes draw their strength from warm ocean waters. So as the ocean continues to absorb heat, should we expect to see more intense hurricanes, tropical storms and typhoons? 

Probably, according to recent research led by NOAA scientists . The research, which analyzed findings from over 90 peer-reviewed studies, found that warming of the surface ocean from human-caused climate change is likely fueling more powerful tropical cyclones. And as sea levels rise, the destructive power of tropical cyclones is amplified, as higher sea levels can result in more intense flooding. ⁣NOAA scientists  have also concluded  that climate change has been influencing the pattern of where tropical cyclones have been increasing or decreasing in occurrence. Researchers are still working to understand the link between climate and hurricanes – check out this page for the most up-to-date science.

4. Tracking warming in the Great Lakes

Like the ocean, freshwater is also impacted by Earth’s warming temperatures. In the Great Lakes, scientists who monitor winter ice cover say that, though ice cover tends to be variable from year to year, the data show a long-term trend of ice decline over the last several decades. Research has also shown that the Great Lakes’ deep waters aren’t immune to warming: As climate change has gradually delayed the onset of autumn in the Great Lakes region, the deep waters of Lake Michigan have started showing shorter winter seasons.  Increases in the lakes’ water temperatures can have serious impacts, including disruptions in the food web that could affect fisheries and recreation, which are important parts of the regional economy. 

5. Working towards climate resilience

From sunny day flooding creating hazards for coastal regions in Florida, to summer heat waves posing risks to communities without air conditioning in the Northeast, climate change creates a range of challenges and dangers for communities. NOAA is helping communities become more resilient to these changes. In Utqiaġvik, Alaska, for instance, NOAA Sea Grant and partners are working with the local community  to better understand risks of flooding and shoreline erosion, helping them better prepare for storms. The NOAA Regional Integrated Sciences and Assessments (RISA) program also funds research and engagement to help Americans prepare for climate change. For instance, the Northeast RISA team worked with New York City officials to map out where in the city extreme heat was having the most impact, so that the city could take action to protect at-risk residents. The U.S. Climate Resilience Toolkit also makes it easy for people to learn more about climate-related risks and opportunities in their area, giving them the knowledge they need to make their communities more climate resilient. 

To learn more NOAA’s work on climate change, visit climate.gov , and consider subscribing  to the This Week on Climate.gov newsletter.

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You Asked, We Answered: Some Burning Climate Questions

Reporters from the Climate Desk gathered reader questions and are here to help explain some frequent puzzlers.

What’s one thing you want to know about climate change? We asked, and hundreds of you responded.

The topic, like the planet, is vast. Overwhelming. Complex. But there’s no more important time to understand what is happening and what can be done about it.

Why are extreme cold weather events happening if the planet is warming?

I understand that scientists believe that some extreme cold weather events are due to climate change, but I don’t quite understand how, especially if Earth is getting warmer overall. Could you explain this? — Gabriel Gutierrez, West Lafayette, Ind.

By Maggie Astor

The connection between climate change and extreme cold weather involves the polar jet stream in the Northern Hemisphere, strong winds that blow around the globe from west to east at an altitude of 5 to 9 miles. The jet stream naturally shifts north and south, and when it shifts south, it brings frigid Arctic air with it.

A separate wind system, called the polar vortex , forms a ring around the North Pole. When the vortex is temporarily disrupted — sometimes stretched or elongated, and other times broken into pieces — the jet stream tends to take one of those southward shifts. And research “suggests these disruptions to the vortex are happening more often in connection with a rapidly warming, melting Arctic, which we know is a clear symptom of climate change,” said Jennifer A. Francis, a senior scientist at the Woodwell Climate Research Center.

In other words, as climate change makes the Arctic warmer, the polar vortex is being more frequently disrupted in ways that allow Arctic air to escape south. And while temperatures are increasing on average, Arctic air is still frigid much of the time. Certainly frigid enough to cause extreme cold snaps in places like, say, Texas that are not accustomed to or prepared for them.

Where the extreme cold occurs depends on the nature of the disruption to the polar vortex. One type of disruption brings Arctic air into Europe and Asia. Another type brings Arctic air into the United States, and “that’s the type of polar vortex disruption that’s increasing the fastest,” said Judah L. Cohen, the director of seasonal forecasting at Atmospheric and Environmental Research, a private organization that works with government agencies.

It is important to note that these atmospheric patterns are extremely complicated, and while studies have shown a clear correlation between the climate-change-fueled warming of the Arctic and these extreme cold events, there is some disagreement among scientists about whether the warming of the Arctic is directly causing the extreme cold events. Research on that question is ongoing.

How will climate change affect biodiversity?

What impact will climate change have on biodiversity? How are they interlinked? How do the roles of developing versus developed countries differ, for example the United States and India? — A reader in India

By Catrin Einhorn

Warmer oceans are killing corals . Rising sea levels threaten the beaches that sea turtles need for nesting, and hotter temperatures are causing more females to be born. Changing seasons are increasingly out of step with the conditions species have evolved to depend on.

And then there are the polar bears , long a symbol of what could be lost in a warming world.

Climate change is already affecting plants and animals in ways that scientists are racing to understand. One study predicted sudden die offs , with large segments of ecosystems collapsing in waves. This has already started in coral reefs, scientists say, and could start in tropical forests by the 2040s.

Keeping global warming under 2 degrees Celsius, or 3.6 degrees Fahrenheit, the upper limit outlined by the Paris Agreement, would reduce the number of species exposed to dangerous climate change by 60 percent, the study found.

Despite these grim predictions, climate change isn’t yet the biggest driver of biodiversity loss. On land, the largest factor is the ways in which people have reshaped the terrain itself, creating farms and ranches, towns and cities, roads and mines from what was once habitat for myriad species. At sea, the main cause of biodiversity loss is overfishing. Also at play: pollution, introduced species that outcompete native ones, and hunting. A sobering report in 2019 by the leading international authority on biodiversity found that around a million species were at risk of extinction, many within decades.

While climate change will increasingly drive species loss, that’s not the only way in which the two are interlinked. Last year the same biodiversity panel joined with its climate change counterpart to issue a paper declaring that neither crisis could be addressed effectively on its own. For example, intact ecosystems like peatlands and forests both nurture biodiversity and sequester carbon; destroy them, and they turn into emitters of greenhouse gasses as well as lost habitat.

What to do? The science is clear that the world must transition away from fossil fuels far more quickly than is happening. Deforestation must stop . Consuming less meat and dairy would free up farmland for restoration , providing habitat for species and stashing away carbon. Ultimately, many experts say, we need a transformation from an extraction-based economy to a circular one. Like nature’s cycle, our waste — old clothes, old smartphones, old furniture — must be designed to provide the building blocks of what comes next.

Countries around the world are working on a new United Nations biodiversity agreement , which is expected to be approved later this year. One sticking point: How much money wealthy countries are willing to give poorer ones to protect intact natural areas, since wealthy countries have already largely exploited theirs.

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What’s the status of U.S. climate legislation and emissions?

Where is the trimmed back version of climate legislation at? Joe Manchin reportedly said he would support such a bill. What do you know about the bill and will it pass with just Democrats? — Richard Buttny, Virgil, N.Y.

What is the current stated U.S. goal regarding reducing greenhouse gases and climate change, and how likely is it that we will achieve that goal? What do we need to do today to make progress toward achieving that goal? — Kathy Gray, Oak Ridge, Tenn.

By Lisa Friedman

Richard, as to the last part of your question, honestly, at this point your guess is as good as ours.

But here is what we know so far. Senator Joe Manchin III, Democrat of West Virginia, the most powerful man in Congress because his support in an evenly divided Senate is key, effectively killed President Biden’s Build Back Better climate and social spending legislation when he ended months of negotiations last year, saying he could not support the package .

A few weeks ago amid talks of revived discussions, Mr. Manchin was blunt. “There is no Build Back Better legislation,” he told reporters. Mr. Manchin also has not committed to passing a smaller version of the original $1 trillion spending plan. He has, however, voiced support for an “all of the above” energy package that increases oil and gas development.

Democrats hope that billions of dollars in tax incentives for wind, solar, geothermal and electric vehicle charging stations can also make its way into such a package. But relations between the White House and Mr. Manchin are rocky and it is unclear whether such a bill could pass before lawmakers leave town for an August recess.

To your emissions question, Kathy, Mr. Biden has pledged to cut United States emissions 50 to 52 percent below 2005 levels by 2030 . Energy experts say it is a challenging but realistic goal, and critical for helping the world avert the worst impacts of climate change.

It’s not going to be easy. So far there are few regulations and even fewer laws that can help achieve that target. Mr. Biden’s centerpiece legislation, the Build Back Better Act, includes $550 billion in clean energy tax incentives that researchers said could get the country about halfway to its goal. But, as noted, that bill is stalled in the Senate . Even if it manages to win approval this year, the administration will still have to enact regulations on things like power plants and automobile emissions to meet the target.

Will our drinking water be safe?

A lot of coverage on climate change deals with rising sea levels and extreme weather — droughts, floods, etc. My question is more about how climate change will affect drinking water and access to safe clean water. Are we in danger within our current lifetime to see an impact to safe water within the U.S. due to climate change? — Jessica, Silver Spring, Md.

By Christopher Flavelle

Climate change threatens Americans’ access to clean drinking water in a number of ways. The most obvious is drought: Rising temperatures are reducing the snowpack that supplies drinking water for much of the West.

But drought is far from the only climate-related threat to America’s water. Along the coast, cities like Miami that draw drinking water from underground aquifers have to worry about rising seas pushing saltwater into those aquifers , a process called saltwater intrusion. And rising seas also push up groundwater levels, which can cause septic systems to stop working, pushing unfiltered human waste into that groundwater.

Even in cities far from the coast, worsening floods are overwhelming aging sewer systems , causing untreated storm water and sewage to reach rivers and streams more frequently . And some 2,500 chemical sites are in areas at risk of flooding, which could cause those chemicals to leach into the groundwater.

In some cases, protecting drinking water from the effects of climate change is possible, so long as governments can find enough money to upgrade infrastructure — building new systems to contain storm water, for example, or better protect chemicals from being released during a flood.

Far harder will be finding new supplies of water to make up for what’s lost as temperatures rise. Some communities are responding by pumping more water from the ground. But if those aquifers are depleted faster than rainwater can replenish them, they will eventually run dry, a concern with the Ogallala Aquifer that supports much of the High Plains.

Even with significant reductions in water use, climate change could reduce the number of people that some regions can support, and leave more areas dependent on importing water.

Can you solve drought by piping water across the country?

Why don’t we create a national acequia system to capture excess rain falling primarily in the Eastern United States and pipeline it to the drought in the West? — Carol P. Chamberland, Albuquerque, N.M

The idea of taking water from one community and giving it to another has some basis in American history. In 1913, Los Angeles opened an aqueduct to carry water from Owens Valley, 230 miles north of the city, to sustain its growth.

But the project, in addition to costing some $23 million at the time, greatly upset Owens Valley residents, who so resented losing their water that they took to dynamiting the aqueduct. Repeatedly .

Today, there are some enormous water projects in the United States, though building a pipeline that spanned a significant stretch of the country would be astronomically more difficult. The distance between Albuquerque, for example, and the Mississippi River — perhaps the closest hypothetical starting point for such a pipeline — is about 1,000 miles, crossing at least three states along the way. Moving that water all the way to Los Angeles would mean piping it at least 1,800 miles across five states.

So the engineering and permitting challenges alone would be daunting. And that’s assuming the local and state governments that would have to give up their water would be willing to do so.

China dealt with similar challenges to build a colossal network of waterways that is transferring water from the country’s humid south to its dry north. But of course, China’s system of government makes engineering feats of that scale somewhat more feasible to pull off.

For the United States, it would be easier to just build a series of desalination plants along the West coast, according to Greg Pierce, director of the Human Right to Water Solutions Lab at the University of California, Los Angeles. And before turning to desalination, which is itself energy-intensive and thus expensive, communities in the West should work harder at other steps, such as water conservation and recycling, he said.

“It’s not worth it,” Dr. Pierce said of the pipeline idea. “You’d have to exhaust eight other options first.”

Is the weather becoming more extreme than scientists predicted?

How can we have faith in climate modeling when extreme events are much worse than predicted? Given “unexpected” extreme events like the 2021 Pacific Northwest heat wave and extreme heat in Antarctica that appear to shock scientists, it’s difficult for me to trust the I.P.C.C.’s framing that we haven’t run out of time. — Kevin, Herndon, Va.

By Raymond Zhong

Climate scientists have said for a long time that global warming is causing the intensity and frequency of many types of extreme weather to increase. And that’s exactly what has been happening. But global climate models aren’t really designed to simulate extreme events in individual regions. The factors that shape individual heat waves, for instance, are very local. Large-scale computer models simply can’t handle that level of detail quite yet.

That said, sometimes there are events that seem so anomalous that they make scientists wonder if they reflect something totally new and unforeseen, a gap in our understanding of the climate. Some researchers put the 2021 Pacific Northwest heat wave in that category, and are working to figure out whether they need to re-evaluate some of their assumptions.

For its part, the I.P.C.C. has hardly failed to acknowledge what’s happening with extreme weather. But its mandate is to assess the whole range of climate research, which might make it lean toward the middle of the road in its summaries. A decade ago, when a group of researchers looked back at the panel’s assessments from the early 2000s, they found that it generally underestimated the actual changes in sea level rise, increases in surface temperatures, intensity of rainfall and more. They blamed the instinct of scientists to avoid making conclusions that seem “excessively dramatic,” perhaps out of fear of being called alarmist.

The panel’s latest report, from April , concluded that we haven’t run out of time to slow global warming, but only if nations and societies make some huge changes right away. That’s a big if.

How can I hear from climate scientists themselves?

Why are climate change scientists faceless, aloof, terrible communicators and absent from social media? — A reader in Dallas

Climate science may not yet have its Bill Nye or its Neil deGrasse Tyson, but plenty of climate scientists are passionate about communicating their work to the public. Lots of them are on Twitter. Here’s a (very small) cross-section of people to follow, in alphabetical order:

Alaa Al Khourdajie : Senior scientist in London with the Intergovernmental Panel on Climate Change, the body of experts convened by the United Nations that puts out regular, authoritative surveys of climate research. Tweets on climate change economics and climate diplomacy.

Andrew Dessler : Professor of atmospheric sciences at Texas A&M University. Elucidator of energy and renewables, climate models and Texas.

Zeke Hausfather : Climate research lead at the payment processing company Stripe and scientist at Berkeley Earth, a nonprofit research group. A seemingly tireless chronicler, charter and commentator on all things climate.

David Ho : Climate scientist at the University of Hawaii at Manoa and École Normale Supérieure in Paris. Talks oceans and carbon dioxide removal, with wry observations on transit, cycling and life in France, too.

Twila Moon : Deputy lead scientist at the National Snow and Ice Data Center in Boulder, Colo. Covers glaciers, polar regions and giant ice sheets, and why we should all care about what happens to them.

Maisa Rojas : Climatologist at the University of Chile and Chile’s current environment minister. Follow along for slices of life at the intersection of science and government policy.

Sonia I. Seneviratne : Professor of land-climate dynamics at ETH Zurich in Switzerland. Tweets on extreme weather, greenhouse gas emissions and European energy policy.

Chandni Singh : Researcher on climate adaptation at the Indian Institute for Human Settlements in Bangalore. Posts about how countries and communities are coping with climate change, in both helpful ways and not so helpful ones.

Kim Wood : Geoscientist and meteorologist at Mississippi State University. A fount of neat weather maps and snarky GIFs.

What kind of trees are best to plant for the planet?

The world is trying to reforest the planet by planting nonnative trees like eucalyptus. Is this another disastrous plan? Shouldn’t they be planting native trees? — Katy Green, Nashville

Ecologists would say planting native trees is the best choice. We recently published an article on this very topic , examining how tree planting can resurrect or devastate ecosystems, depending on what species are planted and where.

To be sure, people need wood and other tree products for all kinds of reasons, and sometimes nonnative species make sense. But even when the professed goal is to help nature, the commercial benefits of certain trees, like Australian eucalyptus in Africa and South America or North American Sitka spruce in Europe, often win out.

A new standard is in development that would score tree planting projects on how well they’re doing with regard to biodiversity, with the aim of helping those with poor scores to improve.

The same ecological benefit of planting native species also holds true for people’s yards. Doug Tallamy, a professor of entomology at the University of Delaware, worked with the National Wildlife Federation to develop this tool to help people find native trees, shrubs and flowers that support the most caterpillars, which in turn feed baby birds .

Can we engineer solutions to atmospheric warming?

Why are we not investing in scalable solutions that can remove carbon or reduce solar radiation? — Hayes Morehouse, Hayward, Calif.

By Henry Fountain

As a group, these types of solutions are referred to as geoengineering, or intentional manipulation of the climate. Geoengineering generally falls into two categories: removing some of the carbon dioxide already in the atmosphere so Earth traps less heat, known as direct air capture, or reducing how much sunlight reaches Earth’s surface so that there is less heat to begin with, usually called solar radiation management.

There are a few companies developing direct air capture machines, and some have deployed them on a small scale. According to the International Energy Agency, these projects capture a total of about 10 thousand tons of CO2 a year, a tiny fraction of the roughly 35 billion tons of annual energy-related emissions. Removing enough CO2 to have a climate impact would take a long time and require many thousands of machines, all of which would need energy to operate.

The captured gas would also have to be securely stored to keep it from re-entering the atmosphere. Those hurdles make direct air capture a long shot, especially since, for now at least, there are few financial incentives to overcome them. No one wants to pay to remove carbon dioxide from the air and bury it underground.

Solar radiation management is a different story. The basics of how to do it are known: inject some kind of chemical (perhaps sulfur dioxide) into the upper atmosphere, where it would reflect more of the sun’s rays. Relatively speaking, it wouldn’t be all that expensive (a fleet of high-flying planes would probably suffice) although once started it would have to continue indefinitely.

The major hurdle to developing the technology has been grave concern among many scientists, policymakers and others about unintended consequences that might result, and about the lack of a structure to govern its deployment. To date, there have been almost no real-world studies of the technology .

How do we know how warm the planet was in the 1800s?

One key finding of climate science is that global temperatures have increased by 2 degrees Fahrenheit since the late 1800s. How can we possibly have reliable measures of global temperatures from back then, keeping in mind that oceans cover about 70 percent of the globe and that a large majority of land has never been populated by humans to any significant degree? — Robert, Madison, Wis.

The mercury thermometer was invented in the early 1700s, and by the mid- to late 19th century, local temperatures were being monitored continuously in many locations, predominantly in the United States, Europe and the British colonies. By 1900, there were hundreds of recording stations worldwide, but over half of the Southern Hemisphere still wasn’t covered. And the techniques could be primitive. To measure temperatures at the sea’s surface, for instance, the most common method before about 1940 was to toss a bucket overboard a ship, haul it back up with a rope and read the temperature of the water inside.

To turn these spotty local measurements into estimates of average temperatures globally, across both land and ocean, climate scientists have had to perform some highly delicate analysis . They’ve used statistical models to fill in the gaps in direct readings. They’ve taken into account when weather stations changed locations or were situated close to cities that were hot for reasons unrelated to larger temperature trends.

They have also used some clever techniques to try to correct for antiquated equipment and methods. Those bucket readings , for example, might be inaccurate because the water in the bucket cooled down as it was pulled aboard. So scientists have scoured various nations’ maritime archives to determine what materials their sailors’ buckets were made of — tin, wood, canvas, rubber — during different periods in history and adjusted the way they incorporate those temperature recordings into their computations.

Such analysis is fiendishly tricky. The numbers that emerge are uncertain estimates, not gospel truth. Scientists are working constantly to refine them. Today’s global temperature measurements are based on a much broader and more quality-controlled set of readings, including from ships and buoys in the oceans.

But having a historical baseline, even an imperfect one, is important. As Roy L. Jenne, a researcher at the National Center for Atmospheric Research, wrote in a 1975 report on the institution’s collections of climate data: “Although they are not perfect, if they are used wisely they can help us find answers to a number of problems.”

Does producing batteries for electric cars damage the environment more than gas vehicles do?

Is the environmental damage collecting metals/producing batteries for electric cars more dangerous to the environment than gas powered vehicles? — Sandy Rogers, San Antonio, Texas

By Hiroko Tabuchi

There’s no question that mining the metals and minerals used in electric car batteries comes with sizable costs that are not just environmental but also human.

Much of the world’s cobalt, for example, is mined in the Democratic Republic of Congo , where corruption and worker exploitation has been widespread. Extracting the metals from their ores also requires a process called smelting, which can emit sulfur oxide and other harmful air pollution.

Beyond the minerals required for batteries, electric grids still need to become much cleaner before electric vehicles are emissions free.

Most electric vehicles sold today already produce significantly fewer planet-warming emissions than most cars fueled with gasoline, but a lot still depends on how much coal is being burned to generate the electricity they use.

Still, consider that batteries and other clean technology require relatively tiny amounts of these critical minerals, and that’s only to manufacture them. Once a battery is in use, there are no further minerals necessary to sustain it. That’s a very different picture from oil and gas, which must constantly be drilled from the ground, transported via pipelines and tankers, refined and combusted in our gasoline cars to keep those cars moving, said Jim Krane, a researcher at Rice University’s Baker Institute for Public Policy in Houston. In terms of environmental and other impacts, he said, “There’s just no comparison.”

How close are alternatives to fuel-powered aircraft?

As E. V.s are to gas-powered cars, are there greener alternatives to fuel-powered planes that are close to commercialization? — Rashmi Sarnaik, Boston

There are alternatives to fossil-fuel-powered aircraft in development, but whether they are close to commercialization depends on how you define “close.” It’s probably fair to say that the day when a significant amount of air travel is on low- or zero-emissions planes is still far-off.

There has been some work on using hydrogen , including burning it in modified jet engines. Airbus and the engine manufacturer CFM International expect to begin flight testing a hydrogen-fueled engine by the middle of the decade.

As with cars, though, most of the focus in aviation has been on electric power and batteries. The main problem with batteries is how little energy they supply relative to their weight. In cars that’s less of an obstacle (they don’t have to get off the ground, after all) but in aviation, batteries severely limit the size of the plane and how far it can fly.

One of the biggest battery-powered planes to fly so far was a modified Cessna Grand Caravan, test-flown by two companies, Magnix and Aerotec. Turboprop Grand Caravans can carry 10 or more people up to 1,200 miles. The companies said theirs could fly four or five people 100 miles or less.

The limitations of batteries, at least for now, have led some companies to work on other designs. Some use fuel cells, which work like batteries but can continuously supply electricity using hydrogen or other fuel. Others use hybrid systems — like hybrid cars, combining batteries and fossil-fuel-powered engines. In one approach, the engines provide some power and also keep the batteries charged. In another, the engines are used in takeoff and descent, when more power is needed, and the batteries for cruising, which requires less power. That keeps the number of batteries, and the weight, down.

Can countries meet the goals they set in the Paris agreement?

What countries, if any, have a realistic chance of meeting their Paris agreement pledges? — Michael Svetly, Philadelphia

According to Climate Action Tracker , a research group that analyzes climate goals and policies, very few. Ahead of United Nations talks in Glasgow last year, the organization found most major emitters of carbon dioxide, including the United States and China, are falling short of their pledge to stabilize global warming around 1.5 degrees Celsius, or 2.7 degrees Fahrenheit.

A few are doing better than most, including Costa Rica and the United Kingdom. Just one country was on track to meet its promises: Gambia, a small West African nation that has been bolstering its renewable energy use.

What will happen to N.Y.C.?

How is N.Y.C. planning for relocation or redevelopment, or both, of its many low-lying neighborhoods as floodwaters become too high to levee? — A reader in North Bergen, N.J.

New York City has yet to announce plans to fully relocate entire neighborhoods threatened by climate change, with all the steps that would entail: determining which homes to buy, getting agreement from homeowners, finding a new patch of land for the community, building new infrastructure, securing funding and so on.

Relocation projects on that scale, often described as “managed retreat,” remain extremely rare in the United States. What projects have been attempted so far have mostly been in rural areas or small towns , and their success has been mixed.

And the idea of pulling back from the water, while never easy, is especially fraught in New York City, which has some of the highest real estate values in the country. Those high values have been used to justify fantastically expensive projects to protect low-lying land in the city, rather than abandon it — like a $10 billion berm along the South Street Seaport , or a $119 billion sea wall in New York Harbor .

Perhaps unsurprisingly, then, the city’s most recent Comprehensive Waterfront Plan , issued in December, makes no mention of managed retreat. But the plan does include what it calls “housing mobility” — policies aimed at helping individual households move to safer areas, for example by giving people money to buy a new home on higher ground, as well as paying for moving and other costs. The city also says it is limiting the density of new development in high-risk areas.

Robert Freudenberg, a vice president of the Regional Plan Association, a nonprofit planning group in New York, New Jersey and Connecticut, gave city officials credit for beginning to talk about the idea that some areas can’t be protected forever.

“It’s an extremely challenging topic,” Mr. Freudenberg said. But as flooding gets worse, he added, “we can’t not talk about it.”

As oceans rise, will the Great Lakes, too?

The oceans are predicted to rise and affect coastal areas and cities, however, does this rise also affect the coastal areas of the Great Lakes, as the lakes are connected to the Atlantic Ocean via the St. Lawrence River and one would have to assume they would eventually be impacted? — Terri Messinides, Madison, Wis.

The Great Lakes are not directly threatened by rising oceans because of their elevation: The lowest of them, Lake Ontario, is about 240 feet above sea level. The St. Lawrence River carries water from the lakes to the Atlantic Ocean, but because of the elevation change, rising waters in the Atlantic can’t travel in the other direction.

That said, climate change is causing increasingly frequent and intense storms in the Great Lakes region, and the effects, including higher water levels and more flooding, are in many respects the same as those caused by rising seas. It’s just a different manifestation of climate change.

When it comes to precipitation, the past five years, from April 2017 through March 2022, the last month for which complete data is available, have been the second-wettest on record for the Great Lakes Basin, according to records kept by the National Oceanic and Atmospheric Administration . The water has risen accordingly. In 2019, water levels in the lakes hit 100-year highs , causing severe flooding and shoreline erosion.

At the same time, higher temperatures increase the rate of evaporation, which can lead to abnormally low water levels. People who live around the Great Lakes can expect to see both extremes — high water driven by severe rainfall, and low water driven by evaporation — happen more often as the climate continues to warm.

What is the environmental cost of cryptocurrency?

Can you tell us about the damage being done to our environment by crypto mining? I’ve heard the mining companies are trying to switch to renewable energy, yet at the same time reopening old coal power plants to provide the huge amounts of electricity they need. — Barry Engelman, Santa Monica, Calif.

Cryptomining, the enigmatic way in which virtual cryptocurrencies like Bitcoin are created (and which is also behind technology like NFTs ), requires a whole lot of computing power, is highly energy-intensive and generates outsize emissions. We delved into that process, and its environmental impact in this article — but suffice to say the problem isn’t going away soon.

The way Bitcoin is set up, using a process called “proof of work,” means that as interest in cryptocurrencies grows and more people start mining, more energy is required to mine a single Bitcoin. Researchers at Cambridge University estimate that mining Bitcoin uses more electricity than midsize countries like Norway. In New York, an influx of Bitcoin miners has led to the reopening of mothballed power plants.

But you might wonder about the traditional financial system: doesn’t that use energy, too? Yes, of course. But Bitcoin, for all its hype, still makes up just a few percent of all the world’s money or its transactions. So even though one industry study estimated that Bitcoin consumes about a 10th of the energy required by the traditional banking system, that still means Bitcoin’s energy use is outsize.

To address its high emissions footprint, cryptomining has increasingly tapped into renewable forms of energy, like hydroelectric power. But figuring out exactly just how much renewable energy Bitcoin miners use can be tricky. For one, we don’t exactly know where many of these miners are. We do know a lot of crypto miners used to be in China, where they had access to large amounts of hydro power. But now that they’ve largely been kicked out, cryptomining’s global climate impact has likely gotten worse .

In the United States, cryptominers have started to tap an unconventional new energy source: drilled gas, collected at oil and gas wells. The miners argue that this gas would otherwise have been flared or vented into the atmosphere, so no excess emissions are created. The reality is not that clear cut: If the presence of those cryptominers disincentivizes oil and gas companies from piping away that gas to be used elsewhere, any savings effect is blunted.

Other efforts are afoot to make cryptomining less damaging for the environment, including an alternative way of cryptomining involving a process called “proof of stake,” that doesn’t require miners to use as much energy. But unless Bitcoin, the most popular cryptocurrency, switches over, that’s going to do little to dent miners’ energy use.

How much do volcanoes contribute to global warming?

What does the data look like for greenhouse gas emissions in the last 200 years if volcanic activity was subtracted out? — Haley Rowlands, Boston

Volcanic activity generates 130 million to 440 million tons of carbon dioxide per year, according to the United States Geological Survey . Human activity generates about 35 billion tons of carbon dioxide per year — 80 times as much as the high-end estimate for volcanic activity, and 270 times as much as the low-end estimate. And that’s carbon dioxide. Human activity also emits other greenhouse gases, like methane, in far greater quantities than volcanoes.

The largest volcanic eruption in the past century was the 1991 eruption of Mount Pinatubo in the Philippines; if an explosion that size happened every day, NASA has calculated , it would still release only half as much carbon dioxide as daily human activity does. The annual emissions from cement production alone, one small component of planet-warming human activity, are greater than the annual emissions from every volcano in the world.

There is also no evidence that volcanic activity has increased over the past 200 years. While there have been more documented eruptions, researchers at the Smithsonian Institution’s Global Volcanism Program found that this was attributable not to an actual trend, but rather to “increases in populations living near volcanoes to observe eruptions and improvements in communication technologies to report those eruptions.”

All told, volcanic activity accounts for less than 1 percent of greenhouse gas emissions, which is not enough to contribute in any meaningful way to the increase we’ve seen over the past 200 years. The Intergovernmental Panel on Climate Change found in 2013 (see Page 56 of its report ) that the climatic effects of volcanic activity were “inconsequential” over the scale of a century.

Do carbon dioxide concentrations vary around the globe?

Why is the concentration of carbon dioxide in the atmosphere at Mauna Loa Observatory in Hawaii used as the global reference? It’s only one point on Earth. Do concentrations vary between different parts of the world? — Evan, Boston

At any given moment, levels of carbon dioxide in the air vary from place to place, depending on the amount of vegetation and human activity nearby. Which is why, as a location to monitor the average state of the atmosphere, at least over a large part of the Northern Hemisphere, a barren volcano in the middle of the Pacific has much to offer. It’s high above the ground and far enough from major sources of industrial pollution but still relatively accessible to researchers.

Today, the National Oceanic and Atmospheric Administration studies global carbon dioxide levels by looking at readings from Mauna Loa Observatory and a variety of other sources. These include observatories in Alaska, American Samoa and the South Pole, tall towers across the United States, and samples collected by balloons, aircraft and volunteers around the world. ( Here’s a map of all those sites.)

NOAA also checks its measurements at Mauna Loa against others from the same location, including ones taken independently, using different methods, by the Scripps Institution of Oceanography . On average, the difference in their monthly estimates is tiny.

Could a ‘new ice age’ offset global warming?

Will increases in global temperature associated with climate change be mitigated by the coming of a new “ice age?” — Suzanne Smythe, Essex, Conn.

In a “mini ice age,” if it occurred, average worldwide temperatures would drop, thus offsetting the warming that has been caused by emissions of greenhouse gases from the burning of fossil fuels in the last century and a half.

It’s a nice thought: a natural phenomenon comes to our rescue. But it’s not happening, nor is it expected to.

The idea is linked to the natural variability in the amount of the sun’s energy that reaches Earth. The sun goes through regular cycles, lasting about 11 years, when activity swings from a minimum to a maximum. But there are also longer periods of reduced activity, called grand solar minimums. The last one began in the mid-17th century and lasted seven decades.

There is some debate among scientists whether we are entering a new grand minimum . But even if we are, and even if it lasted for a century, the reduction in the sun’s output would not have a significant effect on temperatures. NASA scientists, among others, have calculated that any cooling effect would be overwhelmed by the warming effect of all the greenhouse gases we have pumped, and continue to pump, into the atmosphere.

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Human activity affects global surface temperatures by changing Earth ’s radiative balance—the “give and take” between what comes in during the day and what Earth emits at night. Increases in greenhouse gases —i.e., trace gases such as carbon dioxide and methane that absorb heat energy emitted from Earth’s surface and reradiate it back—generated by industry and transportation cause the atmosphere to retain more heat, which increases temperatures and alters precipitation patterns.

Global warming, the phenomenon of increasing average air temperatures near Earth’s surface over the past one to two centuries, happens mostly in the troposphere , the lowest level of the atmosphere, which extends from Earth’s surface up to a height of 6–11 miles. This layer contains most of Earth’s clouds and is where living things and their habitats and weather primarily occur.

Continued global warming is expected to impact everything from energy use to water availability to crop productivity throughout the world. Poor countries and communities with limited abilities to adapt to these changes are expected to suffer disproportionately. Global warming is already being associated with increases in the incidence of severe and extreme weather, heavy flooding , and wildfires —phenomena that threaten homes, dams, transportation networks, and other facets of human infrastructure. Learn more about how the IPCC’s Sixth Assessment Report, released in 2021, describes the social impacts of global warming.

Polar bears live in the Arctic , where they use the region’s ice floes as they hunt seals and other marine mammals . Temperature increases related to global warming have been the most pronounced at the poles, where they often make the difference between frozen and melted ice. Polar bears rely on small gaps in the ice to hunt their prey. As these gaps widen because of continued melting, prey capture has become more challenging for these animals.

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global warming , the phenomenon of increasing average air temperatures near the surface of Earth over the past one to two centuries. Climate scientists have since the mid-20th century gathered detailed observations of various weather phenomena (such as temperatures, precipitation , and storms) and of related influences on climate (such as ocean currents and the atmosphere’s chemical composition). These data indicate that Earth’s climate has changed over almost every conceivable timescale since the beginning of geologic time and that human activities since at least the beginning of the Industrial Revolution have a growing influence over the pace and extent of present-day climate change .

Giving voice to a growing conviction of most of the scientific community , the Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP). The IPCC’s Sixth Assessment Report (AR6), published in 2021, noted that the best estimate of the increase in global average surface temperature between 1850 and 2019 was 1.07 °C (1.9 °F). An IPCC special report produced in 2018 noted that human beings and their activities have been responsible for a worldwide average temperature increase between 0.8 and 1.2 °C (1.4 and 2.2 °F) since preindustrial times, and most of the warming over the second half of the 20th century could be attributed to human activities.

AR6 produced a series of global climate predictions based on modeling five greenhouse gas emission scenarios that accounted for future emissions, mitigation (severity reduction) measures, and uncertainties in the model projections. Some of the main uncertainties include the precise role of feedback processes and the impacts of industrial pollutants known as aerosols , which may offset some warming. The lowest-emissions scenario, which assumed steep cuts in greenhouse gas emissions beginning in 2015, predicted that the global mean surface temperature would increase between 1.0 and 1.8 °C (1.8 and 3.2 °F) by 2100 relative to the 1850–1900 average. This range stood in stark contrast to the highest-emissions scenario, which predicted that the mean surface temperature would rise between 3.3 and 5.7 °C (5.9 and 10.2 °F) by 2100 based on the assumption that greenhouse gas emissions would continue to increase throughout the 21st century. The intermediate-emissions scenario, which assumed that emissions would stabilize by 2050 before declining gradually, projected an increase of between 2.1 and 3.5 °C (3.8 and 6.3 °F) by 2100.

Many climate scientists agree that significant societal, economic, and ecological damage would result if the global average temperature rose by more than 2 °C (3.6 °F) in such a short time. Such damage would include increased extinction of many plant and animal species, shifts in patterns of agriculture , and rising sea levels. By 2015 all but a few national governments had begun the process of instituting carbon reduction plans as part of the Paris Agreement , a treaty designed to help countries keep global warming to 1.5 °C (2.7 °F) above preindustrial levels in order to avoid the worst of the predicted effects. Whereas authors of the 2018 special report noted that should carbon emissions continue at their present rate, the increase in average near-surface air temperature would reach 1.5 °C sometime between 2030 and 2052, authors of the AR6 report suggested that this threshold would be reached by 2041 at the latest.

The AR6 report also noted that the global average sea level had risen by some 20 cm (7.9 inches) between 1901 and 2018 and that sea level rose faster in the second half of the 20th century than in the first half. It also predicted, again depending on a wide range of scenarios, that the global average sea level would rise by different amounts by 2100 relative to the 1995–2014 average. Under the report’s lowest-emission scenario, sea level would rise by 28–55 cm (11–21.7 inches), whereas, under the intermediate emissions scenario, sea level would rise by 44–76 cm (17.3–29.9 inches). The highest-emissions scenario suggested that sea level would rise by 63–101 cm (24.8–39.8 inches) by 2100.

The scenarios referred to above depend mainly on future concentrations of certain trace gases, called greenhouse gases , that have been injected into the lower atmosphere in increasing amounts through the burning of fossil fuels for industry, transportation , and residential uses. Modern global warming is the result of an increase in magnitude of the so-called greenhouse effect , a warming of Earth’s surface and lower atmosphere caused by the presence of water vapour , carbon dioxide , methane , nitrous oxides , and other greenhouse gases. In 2014 the IPCC first reported that concentrations of carbon dioxide, methane, and nitrous oxides in the atmosphere surpassed those found in ice cores dating back 800,000 years.

Of all these gases, carbon dioxide is the most important, both for its role in the greenhouse effect and for its role in the human economy. It has been estimated that, at the beginning of the industrial age in the mid-18th century, carbon dioxide concentrations in the atmosphere were roughly 280 parts per million (ppm). By the end of 2022 they had risen to 419 ppm, and, if fossil fuels continue to be burned at current rates, they are projected to reach 550 ppm by the mid-21st century—essentially, a doubling of carbon dioxide concentrations in 300 years.

A vigorous debate is in progress over the extent and seriousness of rising surface temperatures, the effects of past and future warming on human life, and the need for action to reduce future warming and deal with its consequences. This article provides an overview of the scientific background related to the subject of global warming. It considers the causes of rising near-surface air temperatures, the influencing factors, the process of climate research and forecasting, and the possible ecological and social impacts of rising temperatures. For an overview of the public policy developments related to global warming occurring since the mid-20th century, see global warming policy . For a detailed description of Earth’s climate, its processes, and the responses of living things to its changing nature, see climate . For additional background on how Earth’s climate has changed throughout geologic time , see climatic variation and change . For a full description of Earth’s gaseous envelope, within which climate change and global warming occur, see atmosphere .

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Climate change widespread, rapid, and intensifying – ipcc.

GENEVA, Aug 9 – Scientists are observing changes in the Earth’s climate in every region and across the whole climate system, according to the latest Intergovernmental Panel on Climate Change (IPCC) Report, released today. Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion—such as continued sea level rise—are irreversible over hundreds to thousands of years.

However, strong and sustained reductions in emissions of carbon dioxide (CO 2 ) and other greenhouse gases would limit climate change. While benefits for air quality would come quickly, it could take 20-30 years to see global temperatures stabilize, according to the IPCC Working Group I report, Climate Change 2021: the Physical Science Basis , approved on Friday by 195 member governments of the IPCC, through a virtual approval session that was held over two weeks starting on July 26.

The Working Group I report is the first instalment of the IPCC’s Sixth Assessment Report (AR6), which will be completed in 2022.

“This report reflects extraordinary efforts under exceptional circumstances,” said Hoesung Lee, Chair of the IPCC. “The innovations in this report, and advances in climate science that it reflects, provide an invaluable input into climate negotiations and decision-making.”

Faster warming

The report provides new estimates of the chances of crossing the global warming level of 1.5°C in the next decades, and finds that unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to close to 1.5°C or even 2°C will be beyond reach.

The report shows that emissions of greenhouse gases from human activities are responsible for approximately 1.1°C of warming since 1850-1900, and finds that averaged over the next 20 years, global temperature is expected to reach or exceed 1.5°C of warming. This assessment is based on improved observational datasets to assess historical warming, as well progress in scientific understanding of the response of the climate system to human-caused greenhouse gas emissions.

“This report is a reality check,” said IPCC Working Group I Co-Chair Valérie Masson-Delmotte. “We now have a much clearer picture of the past, present and future climate, which is essential for understanding where we are headed, what can be done, and how we can prepare.”

Every region facing increasing changes

Many characteristics of climate change directly depend on the level of global warming, but what people experience is often very different to the global average. For example, warming over land is larger than the global average, and it is more than twice as high in the Arctic.

“Climate change is already affecting every region on Earth, in multiple ways. The changes we experience will increase with additional warming,” said IPCC Working Group I Co-Chair Panmao Zhai.

The report projects that in the coming decades climate changes will increase in all regions. For 1.5°C of global warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons. At 2°C of global warming, heat extremes would more often reach critical tolerance thresholds for agriculture and health, the report shows.

But it is not just about temperature. Climate change is bringing multiple different changes in different regions – which will all increase with further warming. These include changes to wetness and dryness, to winds, snow and ice, coastal areas and oceans. For example:

• Climate change is intensifying the water cycle. This brings more intense rainfall and associated flooding, as well as more intense drought in many regions.
• Climate change is affecting rainfall patterns. In high latitudes, precipitation is likely to increase, while it is projected to decrease over large parts of the subtropics. Changes to monsoon precipitation are expected, which will vary by region.
• Coastal areas will see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion. Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century.
• Further warming will amplify permafrost thawing, and the loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of summer Arctic sea ice.
• Changes to the ocean, including warming, more frequent marine heatwaves, ocean acidification, and reduced oxygen levels have been clearly linked to human influence. These changes affect both ocean ecosystems and the people that rely on them, and they will continue throughout at least the rest of this century.
• For cities, some aspects of climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea level rise in coastal cities.

For the first time, the Sixth Assessment Report provides a more detailed regional assessment of climate change, including a focus on useful information that can inform risk assessment, adaptation, and other decision-making, and a new framework that helps translate physical changes in the climate – heat, cold, rain, drought, snow, wind, coastal flooding and more – into what they mean for society and ecosystems.

This regional information can be explored in detail in the newly developed Interactive Atlas interactive-atlas.ipcc.ch as well as regional fact sheets, the technical summary, and underlying report.

Human influence on the past and future climate

“It has been clear for decades that the Earth’s climate is changing, and the role of human influence on the climate system is undisputed,” said Masson-Delmotte. Yet the new report also reflects major advances in the science of attribution – understanding the role of climate change in intensifying specific weather and climate events such as extreme heat waves and heavy rainfall events.

The report also shows that human actions still have the potential to determine the future course of climate. The evidence is clear that carbon dioxide (CO 2 ) is the main driver of climate change, even as other greenhouse gases and air pollutants also affect the climate.

“Stabilizing the climate will require strong, rapid, and sustained reductions in greenhouse gas emissions, and reaching net zero CO 2 emissions. Limiting other greenhouse gases and air pollutants, especially methane, could have benefits both for health and the climate,” said Zhai.

For more information contact:

IPCC Press Office [email protected] , +41 22 730 8120

Katherine Leitzell [email protected]

Nada Caud (French) [email protected]

Notes for Editors

Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

The Working Group I report addresses the most updated physical understanding of the climate system and climate change, bringing together the latest advances in climate science, and combining multiple lines of evidence from paleoclimate, observations, process understanding, global and regional climate simulations. It shows how and why climate has changed to date, and the improved understanding of human influence on a wider range of climate characteristics, including extreme events. There will be a greater focus on regional information that can be used for climate risk assessments.

The Summary for Policymakers of the Working Group I contribution to the Sixth Assessment Report (AR6) as well as additional materials and information are available at https://www.ipcc.ch/report/ar6/wg1/

Note : Originally scheduled for release in April 2021, the report was delayed for several months by the COVID-19 pandemic, as work in the scientific community including the IPCC shifted online. This is first time that the IPCC has conducted a virtual approval session for one of its reports.

AR6 Working Group I in numbers

234 authors from 66 countries

• 31 – coordinating authors
• 167 – lead authors
• 36 – review editors
• 517 – contributing authors

Over 14,000 cited references

A total of 78,007 expert and government review comments

(First Order Draft 23,462; Second Order Draft 51,387; Final Government Distribution: 3,158)

More information about the Sixth Assessment Report can be found here .

About the IPCC

The Intergovernmental Panel on Climate Change (IPCC) is the UN body for assessing the science related to climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide political leaders with periodic scientific assessments concerning climate change, its implications and risks, as well as to put forward adaptation and mitigation strategies. In the same year the UN General Assembly endorsed the action by the WMO and UNEP in jointly establishing the IPCC. It has 195 member states.

Thousands of people from all over the world contribute to the work of the IPCC. For the assessment reports, IPCC scientists volunteer their time to assess the thousands of scientific papers published each year to provide a comprehensive summary of what is known about the drivers of climate change, its impacts and future risks, and how adaptation and mitigation can reduce those risks.

The IPCC has three working groups: Working Group I , dealing with the physical science basis of climate change; Working Group II , dealing with impacts, adaptation and vulnerability; and Working Group III , dealing with the mitigation of climate change. It also has a Task Force on National Greenhouse Gas Inventories that develops methodologies for measuring emissions and removals. As part of the IPCC, a Task Group on Data Support for Climate Change Assessments (TG-Data) provides guidance to the Data Distribution Centre (DDC) on curation, traceability, stability, availability and transparency of data and scenarios related to the reports of the IPCC.

IPCC assessments provide governments, at all levels, with scientific information that they can use to develop climate policies. IPCC assessments are a key input into the international negotiations to tackle climate change. IPCC reports are drafted and reviewed in several stages, thus guaranteeing objectivity and transparency. An IPCC assessment report consists of the contributions of the three working groups and a Synthesis Report. The Synthesis Report integrates the findings of the three working group reports and of any special reports prepared in that assessment cycle.

About the Sixth Assessment Cycle

At its 41st Session in February 2015, the IPCC decided to produce a Sixth Assessment Report (AR6). At its 42nd Session in October 2015 it elected a new Bureau that would oversee the work on this report and the Special Reports to be produced in the assessment cycle.

Global Warming of 1.5°C , an IPCC special report on the impacts of global warming of 1.5 degrees Celsius above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty was launched in October 2018.

Climate Change and Land , an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems was launched in August 2019, and the Special Report on the Ocean and Cryosphere in a Changing Climate was released in September 2019.

In May 2019 the IPCC released the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories , an update to the methodology used by governments to estimate their greenhouse gas emissions and removals.

The other two Working Group contributions to the AR6 will be finalized in 2022 and the AR6 Synthesis Report will be completed in the second half of 2022.

For more information go to www.ipcc.ch

The website includes outreach materials including videos about the IPCC and video recordings from outreach events conducted as webinars or live-streamed events.

Most videos published by the IPCC can be found on our YouTube and Vimeo channels.

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• In Response to Climate Change, Citizens in Advanced Economies Are Willing To Alter How They Live and Work

Many doubt success of international efforts to reduce global warming

Table of contents.

• Acknowledgments
• Methodology

This analysis focuses on attitudes toward global climate change around the world. For this report, we conducted nationally representative Pew Research Center surveys of 16,254 adults from March 12 to May 26, 2021, in 16 advanced economies. All surveys were conducted over the phone with adults in Canada, Belgium, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, the UK, Australia, Japan, New Zealand, Singapore, South Korea and Taiwan.

In the United States, we surveyed 2,596 U.S. adults from Feb. 1 to 7, 2021. Everyone who took part in the U.S. survey is a member of the Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way nearly all adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories.

This study was conducted in countries where nationally representative telephone surveys are feasible. Due to the coronavirus outbreak, face-to-face interviewing is not currently possible in many parts of the world.

Here are the questions used for the report, along with responses. See our methodology database for more information about the survey methods outside the U.S. For respondents in the U.S., read more about the ATP’s methodology .

A new Pew Research Center survey in 17 advanced economies spanning North America, Europe and the Asia-Pacific region finds widespread concern about the personal impact of global climate change. Most citizens say they are willing to change how they live and work at least some to combat the effects of global warming, but whether their efforts will make an impact is unclear.

Citizens offer mixed reviews of how their societies have responded to climate change, and many question the efficacy of international efforts to stave off a global environmental crisis.

Conducted this past spring, before the summer season ushered in new wildfires , droughts , floods and stronger-than-usual storms , the study reveals a growing sense of personal threat from climate change among many of the publics polled. In Germany, for instance, the share that is “very concerned” about the personal ramifications of global warming has increased 19 percentage points since 2015 (from 18% to 37%).

In the study, only Japan (-8 points) saw a significant decline in the share of citizens deeply concerned about climate change. In the United States, views did not change significantly since 2015.

Young adults, who have been at the forefront of some of the most prominent climate change protests in recent years, are more concerned than their older counterparts about the personal impact of a warming planet in many publics surveyed. The widest age gap is found in Sweden, where 65% of 18- to 29-year-olds are at least somewhat concerned about the personal impacts of climate change in their lifetime, compared with just 25% of those 65 and older. Sizable age differences are also found in New Zealand, Australia, the U.S., France and Canada.

Public concern about climate change appears alongside a willingness to reduce its effects by taking personal steps. Majorities in each of the advanced economies surveyed say they are willing to make at least some changes in how they live and work to address the threat posed by global warming. And across all 17 publics polled, a median of 34% are willing to consider “a lot of changes” to daily life as a response to climate change.

Generally, those on the left of the political spectrum are more open than those on the right to taking personal steps to help reduce the effects of climate change. This is particularly true in the U.S., where citizens who identify with the ideological left are more than twice as willing as those on the ideological right (94% vs. 45%) to modify how they live and work for this reason. Other countries where those on the left and right are divided over whether to alter their lives and work in response to global warming include Canada, the Netherlands, Australia and Germany.

Beyond individual actions, the study reveals mixed views on the broader, collective response to climate change. In 12 of the 17 publics polled, half or more think their own society has done a good job dealing with global climate change. But only in Singapore (32%), Sweden (14%), Germany (14%), New Zealand (14%) and the United Kingdom (13%) do more than one-in-ten describe such efforts as “very good.” Meanwhile, fewer than half in Japan (49%), Italy (48%), the U.S. (47%), South Korea (46%) and Taiwan (45%) give their society’s climate response favorable marks.

Abroad, the U.S. response to climate change is generally seen as wanting. Among the 16 other advanced economies surveyed, only Singaporeans are slightly positive in their assessment of American efforts (53% say the U.S. is doing a “good job” of addressing climate change). Elsewhere judgments are harsher, with six-in-ten or more across Australia, New Zealand and many of the European publics polled saying the U.S. is doing a “bad job” of dealing with global warming. However, China fares substantially worse in terms of international public opinion: A median of 78% across 17 publics describe China’s handling of climate change as “bad,” including 45% who describe the Chinese response as “very bad.” That compares with a cumulative median of 61% who judge the American response as “bad.”

At the cross-national level, the European Union’s response to climate change is viewed favorably by majorities in each of the advanced economies surveyed, except Germany where opinion is split (49% good job; 47% bad job). However, there is still room for improvement, as only a median of 7% across the publics polled describe the EU’s efforts as “very good.” The United Nations’ actions to address global warming are also generally seen in a favorable light: A median of 56% say the multilateral organization is doing a good job. But again, the reviews are tempered, with just 5% describing the UN’s response to climate change as “very good.”

Publics in the advanced economies surveyed are divided as to whether actions by the international community can successfully reduce the effects of global warming. Overall, a median of 52% lack confidence that a multilateral response will succeed, compared with 46% who remain optimistic that nations can respond to the impact of climate change by working together. Skepticism of multilateral efforts is most pronounced in France (65%), Sweden (61%) and Belgium (60%), while optimism is most robust in South Korea (68%) and Singapore (66%).

These are among the findings of a new Pew Research Center survey, conducted from Feb. 1 to May 26, 2021, among 18,850 adults in 17 advanced economies.

People concerned climate change will harm them during their lifetimes

Many people across 17 advanced economies are concerned that global climate change will harm them personally at some point in their lifetime. A median of 72% express at least some concern that they will be personally harmed by climate change in their lifetimes, compared with medians of 19% and 11% who say they are not too or not at all concerned, respectively. The share who say they are very concerned climate change will harm them personally ranges from 15% in Sweden to 57% in Greece.

Roughly two-thirds of Canadians and six-in-ten Americans are worried climate change will harm them in their lifetimes. Only 12% of Canadians and 17% of Americans are not at all concerned about the personal impact of global climate change.

Publics in Europe express various degrees of concern for potential harm caused by climate change. Three-quarters or more of those in Greece, Spain, Italy, France and Germany say they are concerned that climate change will harm them at some point during their lives. Only in Sweden does less than a majority of adults express concern about climate change harming them. Indeed, 56% of Swedes are not concerned about personal harm related to climate change.

In general, Asia-Pacific publics express more worry about climate change causing them personal harm than not. The shares who express concern range from 64% in Australia to 88% in South Korea. About one-third or more in South Korea, Singapore and Australia say they are very concerned climate change will harm them personally.

The share who are very concerned climate change will harm them personally at some point during their lives has increased significantly since 2015 in nearly every country where trend data is available. In Germany, for example, the share who say they are very concerned has increased 19 percentage points over the past six years. Double-digit changes are also present in the UK (+18 points), Australia (+16), South Korea (+13) and Spain (+10). The only public where concern for the harm from climate change has decreased significantly since 2015 is Japan (-8 points).

While many worry climate change will harm them personally in the future, there is widespread sentiment that climate change is already affecting the world around them. In Pew Research Center surveys conducted in 2019 and 2020, a median of 70% across 20 publics surveyed said climate change is affecting where they live a great deal or some amount. And majorities in most countries included as part of a 26-nation survey in 2018 thought global climate change was a major threat to their own country (the same was true across all 14 countries surveyed in 2020 ).

Those who place themselves on the left of the ideological spectrum are more likely than those who place themselves on the right to be concerned global climate change will harm them personally during their lifetime. This pattern is present across all 14 nations where ideology is measured. In 10 of these 14, though, majorities across the ideological left, center and right are concerned climate change will harm them personally.

The difference is starkest in the U.S.: Liberals are 59 percentage points more likely than conservatives to express concern for this possibility (87% vs. 28%, respectively). However, large ideological differences are also present in Australia (with liberals 41 points more likely to say this), the Netherlands (+35), Canada (+30), Sweden (+30) and New Zealand (+23).

Women are more concerned than men that climate change will harm them personally in many of the publics polled. In Germany, women are 13 points more likely than men to be concerned that climate change will cause them harm (82% vs 69%, respectively). Double-digit differences are also present across several publics, including the U.S., Sweden, the UK, South Korea, Singapore, Taiwan, Australia and the Netherlands.

When this question was first asked in 2015 , women were also more likely to express concern than their male counterparts that climate change will harm them in the U.S., Germany, Canada, Japan, Spain and Australia.

Young people have been at the forefront of past protests seeking government action on climate change. In eight places surveyed, young adults ages 18 to 29 are more likely than those 65 and older to be concerned climate change will harm them during their lifetime. The difference is greatest in Sweden, home of youth climate activist Greta Thunberg . Young Swedes are 40 points more likely than their older counterparts to say they are concerned about harm from climate change. Large age gaps are also present in New Zealand (with younger adults 31 points more likely to say this), Australia (+30) and Singapore (+20). And young Americans, French, Canadians and Brits are also more likely to say that climate change will personally harm them in their lifetimes.

While large majorities across every age group in Greece and South Korea are concerned climate change will harm them personally, those ages 65 and older are more likely to hold this sentiment than those younger than 30.

Many across the world willing to change how they live and work to reduce effects of climate change

Many across the publics surveyed say they are willing to make at least some changes to the way they live and work to reduce the effects of climate change. A median of 80% across 17 publics say they would make at least some changes to their lives to reduce the effects of climate change, compared with a median of 19% who say they would make a few changes or no changes at all. The share willing to make a lot of changes ranges from 8% in Japan to 62% in Greece.

In North America, about three-quarters or more of both Canadians and Americans say they are willing to make changes to reduce the effects of climate change.

Large majorities across each of the European publics surveyed say they are willing to change personal behavior to address climate change, but the share who say they are willing to make a lot of changes varies considerably. About half or more in Greece, Italy and Spain say they would make a lot of changes, while fewer than a third in Belgium, Germany and the Netherlands say the same.

Majorities in each of the Asia-Pacific publics polled say they would make some or a lot of changes to how they live and work to combat the effects of climate change, including more than three-quarters in South Korea, Singapore, Australia and New Zealand. But in Japan, fully 44% say they are willing to make few or no changes to how they live and work to address climate change, the largest share of any public surveyed.

In eight countries surveyed, those ages 18 to 29 are more likely than those 65 and older to say they are willing to make at least some changes to how they live and work to help reduce the effects of climate change. In France, for example, about nine-in-ten of those younger than 30 are willing to make changes in response to climate change, compared with 62% of those 65 and older.

Ideologically, those on the left are more likely than those on the right to express willingness to change their behavior to help reduce the effects of global climate change. The ideological divide is widest in the U.S., where 94% of liberals say they are willing to make at least some changes to how they live and work to help reduce the effects of climate change, compared with 45% of conservatives. Large ideological differences are also present between those on the left and the right in Canada (a difference of 26 percentage points), the Netherlands (25 points), Australia (23 points) and Germany (22 points).

In most publics, those with more education are more likely than those with less education to say they are willing to adjust their lifestyles in response to the impact of climate change. 1 In Belgium, for example, those with a postsecondary degree or higher are 14 points more likely than those with a secondary education or below to say they are willing to make changes to the way they live. Double-digit differences are also present between those with more education and less education in France, Germany, New Zealand, the Netherlands and Australia.

And in most places surveyed, those with a higher-than-median income are more likely than those with a lower income to express willingness to make at least some changes to reduce the effects of climate change. For example, in Belgium, about three-quarters (76%) of those with a higher income say they would make changes to their lives, compared with 66% of those with a lower income.

Many are generally positive about how their society is handling climate change

Respondents give mostly positive responses when asked to reflect on how their own society is handling climate change. Around half or more in most places say they their society is doing at least a somewhat good job, with a median of 56% saying this across the 17 advanced economies.

Roughly two-thirds (64%) of Canadians say their country is doing a good job, while nearly half of Americans say the same.

In most of the European publics surveyed, majorities believe their nation’s climate change response is at least somewhat good. Those in Sweden and the UK are especially optimistic, with around seven-in-ten saying their society is doing a good job dealing with climate change. In Europe, Italians are the most critical of their country’s performance: 20% say their society is doing a very bad job, the largest share among all publics surveyed.

Around eight-in-ten in Singapore and New Zealand say their publics are doing a good job – the highest levels among all societies surveyed. This includes around a third (32%) in Singapore who say they are doing a very good job. Adults in the other Asia-Pacific publics surveyed are more circumspect; about half or fewer say their society is doing a good job.

Political ideology plays a role in how people evaluate their own public’s handling of climate change. For adults in 10 countries, those on the right tend to rate their country’s performance with regard to climate change more positively. The difference is most stark in Australia: 69% of those on the right say Australia is handling climate change well, compared with just 19% of those on the left – a 50-point difference. A striking difference also appears in the U.S., where conservatives are 41 points more likely than liberals to say the U.S. is doing a good job dealing with climate change.

Evaluations are also tied to how people view governing parties. In 10 of 17 publics surveyed, people who see the governing party positively are more likely than those with a negative view of the party to think climate change is being handled well. The opposite is true in the U.S., where only 33% of Democrats and Democratic-leaning independents say the U.S. is handling climate change well, compared with 61% of those who do not support the Democratic Party.

Mixed views on whether action by the international community can reduce the effects of climate change

Only a median of 46% across the publics polled are confident that actions taken by the international community will significantly reduce the effects of climate change. A median of 52% are not confident these actions will reduce the effects of climate change.

Canadians are generally divided on whether international climate action can reduce the impact of climate change. And 54% of Americans are not confident in the international community’s response to the climate crisis.

In Europe, majorities in Germany and the Netherlands express confidence that international climate action can significantly address climate change. However, majorities in France, Sweden, Belgium and Italy are not confident in climate actions taken by the international community.

South Koreans and Singaporeans say they are confident in international climate action, but elsewhere in the Asia-Pacific region, public opinion is either divided or leans toward pessimism about international efforts.

Opinion of international organizations, like the United Nations, is linked to confidence that actions taken by the international community will significantly reduce the effects of global climate change. Those with a favorable view of the UN are more confident that actions taken by the international community will significantly reduce the effects of climate change than those with an unfavorable view of the UN. This difference is largest in the U.S., where 61% with a favorable view of the UN say international action will reduce the effects of climate change, compared with just 22% of those with an unfavorable view of the organization. Double-digit differences are present in every public polled.

Similarly, in every EU member state included in the survey, those with favorable views of the bloc are more likely to have confidence in international efforts to combat climate change than those with unfavorable views.

Little consensus on whether international climate action will harm or benefit domestic economies

Relatively few in the advanced economies surveyed think actions taken by the international community to address climate change, such as the Paris climate agreement, will mostly benefit or harm their own economy. A median of 31% across 17 publics say these actions will be good for their economy, while a median of 24% believe such actions will mostly harm their economy. A median of 39% say actions like the Paris climate agreement will have no economic impact.

In Sweden, about half (51%) feel international climate actions will mostly benefit their economy. On the other hand, only 18% in France say their public will benefit economically from international climate agreements.

In no public do more than a third say international action on climate change will harm their economy. But in the U.S., which pulled out of the Paris climate agreement under former President Donald Trump and has just recently rejoined the accord under President Joe Biden, a third say international climate agreements will harm the economy. (For more on how international publics view Biden’s international policy actions, see “ America’s Image Abroad Rebounds With Transition From Trump to Biden .”)

The more widespread sentiment among those surveyed is that climate actions will have no impact on domestic economies. In eight publics, four-in-ten or more hold this opinion, including half in France. And in two places – Japan and Taiwan – one-in-five or more offer no opinion.

Those on the left of the ideological spectrum are more likely than those on the right to say international action to address climate change – such as the Paris Agreement – will mostly benefit their economies. U.S. respondents are particularly divided by ideology. Roughly half (53%) of liberals feel international actions related to climate change will benefit the U.S. economy, compared with just 12% of conservatives. The next largest difference is in Canada, where those on the left are 24 percentage points more likely than those on the right to think this type of international action will benefit their economy.

Those on the right in many publics are, in turn, more likely than those on the left to think international actions such as the Paris Agreement will mostly harm their economies. Here again, ideological divisions in the U.S. are much larger than those in other publics: 65% of conservatives say international climate change actions will harm the American economy, compared with 12% of liberals who say the same.

In several advanced economies, those who say their current economic situation is good are more likely to say that actions taken by the international community to address climate change will mostly benefit their economies than those who say the economic situation is bad. In Sweden, for example, a majority (55%) of those who say the current economic situation is good also believe international action like the Paris Agreement will benefit the Swedish economy, compared with 31% who are more negative about the state of the economy.

Evaluating the climate change response from the EU, UN, U.S. and China

In addition to reflecting on their own public, respondents were asked to evaluate how four international organizations or countries are handling global climate change. Of the entities asked about, the European Union receives the best ratings, with a median of 63% across the 17 publics surveyed saying the EU is doing a good job handling climate change. A median of 56% say the same for the United Nations. Far fewer believe the U.S. or China – the two leading nations in carbon dioxide emissions – are doing a good job.

EU handling of climate change receives high marks in and outside of Europe

Majorities in all but two of the publics surveyed think the EU is doing a good job addressing climate change. However, this positivity is tempered, with most respondents saying the EU’s effort is somewhat good, but few saying it is very good.

Praise for the bloc’s response to climate change is common among the European countries surveyed. In Spain and Greece, around seven-in-ten say the EU is doing at least a somewhat good job, and about six-in-ten or more in the UK, Italy, Sweden and France agree. The Dutch and Germans have more mixed feelings about how the EU is responding to climate change. Notably, only about one-in-ten say the EU is doing a very bad job handling climate change in every European country surveyed but Sweden, where only 5% say so.

Seven-in-ten Canadians believe the EU is doing a good job dealing with climate change, and 62% in the U.S. express the same view.

The Asia-Pacific publics surveyed report similarly positive attitudes on the EU’s climate plans. Around seven-in-ten Australians and Singaporeans consider the EU’s response to climate change at least somewhat good. About six-in-ten or more in New Zealand, South Korea, Japan and Taiwan echo this sentiment.

Climate change actions by UN seen positively among most surveyed

Majorities in most publics also consider the UN response to climate change to be good. A median of 49% across all publics surveyed say that the UN’s actions are somewhat good, and a median of 5% say the actions are very good.

Canadians evaluate the UN’s performance on climate more positively than Americans do. In Canada, roughly six-in-ten say the multilateral organization is doing at least a somewhat good job handling climate change. About half of those in the U.S. agree with that evaluation, with 43% of Americans saying the UN is doing a bad job of dealing with climate change.

In Europe, majorities in Spain, Sweden, the UK, Greece and Italy approve of how the UN is dealing with climate change. Fewer than half of adults in the Netherlands, France and Belgium agree with this evaluation, and only about a third in Germany say the same.

Singaporeans stand out as the greatest share of adults among those surveyed who see the UN’s handling of climate change as good. This includes 14% who say the UN response is very good, which is at least double the share in all other societies surveyed. Majorities in Australia and New Zealand similarly say that the UN is doing a good job.

Many critical of U.S. approach to climate change

In most publics surveyed, adults who say the U.S. is doing a good job of handling climate change are in the minority. A median of 33% say the U.S. is doing a somewhat good job, and a median of just 3% believe the U.S. is doing a very good job.

About half of Americans say their own country is doing a good job in dealing with global climate change, but six-in-ten Canadians say their southern neighbor is doing a bad job.

Across Europe, most think the U.S. is doing a bad job of addressing climate change, including 75% of Germans and Swedes. And at least a quarter in all European nations surveyed except the UK and Greece say the U.S. is doing a very bad job.

Singaporeans offer the U.S. approach to climate change the most praise in the Asia-Pacific region and across all publics surveyed; around half say they see the U.S. strategy positively. New Zealanders are the most critical in the Asia-Pacific region: Only about a quarter say the U.S. is doing at least a somewhat good job.

Political ideology is linked to evaluations of the U.S. climate strategy. In 12 countries, those on the right of the political spectrum are significantly more likely than those on the left to say the U.S. is doing a good job dealing with global climate change. The difference is greatest in Australia, Canada and Italy.

Few give China positive marks for handling of climate change

The publics surveyed are unenthusiastic about how China is dealing with climate change. A median of 18% across the publics say China is doing a good job, compared with a median of 78% who say the opposite. Notably, a median of 45% say that China is doing a very bad job handling climate change.

Just 18% of Americans and Canadians believe China is doing a good job handling climate change.

Similarly, few in Europe think China is dealing effectively with climate change. In fact, more than four-in-ten in nearly all European countries polled say China is doing a very bad job with regards to climate change. Criticism is less common in Greece, where a third give China positive marks for its climate change action.

Adults in the Asia-Pacific region also generally give China poor ratings for dealing with climate change. South Koreans are exceptionally critical; about two-thirds say China is doing a very bad job, the highest share in all publics surveyed. About four-in-ten or more in New Zealand, Japan and Australia concur. Singaporeans stand out, as half say China is doing a good job, nearly 20 percentage points higher than the next highest public.

In nine countries surveyed, those with less education are more positive toward China’s response to climate change than those with more education. Likewise, those with lower incomes are more inclined to provide positive evaluations of China’s climate change response. Those with less education or lower incomes are also less likely to provide a response in several publics.

CORRECTION (Oct. 13, 2021): In the chart “Publics are divided over the economic impact of international actions to address global climate change,” the “Don’t Know” column has been edited to reflect updated percentages to correct for a data tabulation error. These changes did not affect the report’s substantive findings.

• For the purpose of comparing educational groups across publics, education levels are standardized based on the UN’s International Standard Classification of Education (ISCED). The “less education” category is secondary education or below and the “more education” category is postsecondary or above in Australia, Belgium, Canada, Denmark, France, Germany, Italy, Japan, Netherlands, New Zealand, Singapore, South Korea, Spain, Sweden, Taiwan, UK and U.S. ↩

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January 4, 2020

These Are the Biggest Climate Questions for the New Decade

The 2010s brought major climate science advances, but researchers still want to pin down estimates of Arctic melt and sea-level rise

By Chelsea Harvey & E&E News

In this aerial view ice lies in a lake formed by meltwater from the Rhone glacier on August 19, 2019 near Obergoms, Switzerland.

Sean Gallup Getty Images

The 2010s were almost certainly the hottest decade on record — and it showed. The world burned, melted and flooded. Heat waves smashed temperature records around the globe. Glaciers lost ice at accelerating rates. Sea levels continued to swell.

At the same time, scientists have diligently worked to untangle the chaos of a rapidly warming planet.

In the past decade, scientists substantially improved their ability to draw connections between climate change and extreme weather events. They made breakthroughs in their understanding of ice sheets. They raised critical questions about the implications of Arctic warming. They honed their predictions about future climate change.

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As another decade begins, scientists say there are more questions to be answered. We asked climate researchers across a variety of disciplines about the biggest priorities and hottest topics for the 2020s. Here's what they said.

Arctic mysteries

The Arctic is warming faster than anywhere else on Earth, with temperatures rising at least twice as fast as the global average. Many scientists believe that understanding the consequences of Arctic warming is essential for making accurate predictions about climate change around the world.

Some of these links are straightforward. Melting Arctic ice pouring into the ocean can raise global sea levels. Thawing permafrost can release large amounts of carbon dioxide and methane into the atmosphere, potentially accelerating the rate of global warming.

Others are more contentious.

In the last decade, a growing scientific debate has arisen about the influence of Arctic warming on global climate and weather patterns, particularly in the midlatitudes.

Some observational studies have pointed to a statistical connection between Arctic warming and weather events in places like the United States, Europe and parts of Asia — for instance, a link between shrinking sea ice and cold winters in Siberia, or Arctic heat waves and extreme winter weather in the United States.

The trouble is models have a hard time capturing the causes driving these connections.

"No one argues that the Arctic meltdown will affect weather patterns, the question is exactly how," said Arctic climate expert Jennifer Francis, a researcher at Woods Hole Research Center. "So figuring out what's not right in the models will be a major focus. Without realistic models, it's hard to use them to separate Arctic influences from other possible factors."

Resolving the debate will require "a combination of data and modeling," according to NASA climatologist Claire Parkinson. Many scientists are already hard at work on this issue.

One ongoing project known as the Polar Amplification Model Intercomparison Project is conducting a series of coordinated model experiments, all using the same standard methods, to investigate the Arctic climate and its connections to the rest of the globe. Experts say these kinds of projects may help explain why modeling studies conducted by different groups with different methods don't always get the same results.

At the same time, improving the way that physical processes are represented in Arctic climate models is also essential, according to Xiangdong Zhang, an Arctic and atmospheric scientist at the University of Alaska, Fairbanks.

Outside that debate, there are still big questions about the Arctic climate to resolve. Scientists know the Arctic is heating up at breakneck speed — but they're still investigating all the reasons why.

Researchers believe a combination of feedback processes are probably at play. Sea ice and snow help reflect sunlight away from the Earth. As they melt away, they allow more heat to reach the surface, warming the local climate and causing even more melting to occur.

One key question for the coming decade, Zhang said in an email, is "what relative role each of the physical processes plays and how these processes work together" to drive the accelerating warming.

Unraveling these feedbacks will help scientists better predict how fast the Arctic will warm in the future, according to Francis — and how quickly they should expect its consequences to occur. They include vanishing sea ice, thawing permafrost and melting on the Greenland ice sheet.

Oceans and ice

Sea-level rise is one of the most serious consequences of climate change, with the potential to displace millions of people in coastal areas around the world.

At the moment, the world's oceans are rising at an average rate of about 3 millimeters each year. It appears to be speeding up over time. That may not sound like much, but scientists are already documenting an increase in coastal flooding in many places around the world.

Accurately predicting the pace of future sea-level rise is one of the biggest priorities in climate science. And one of the biggest uncertainties about future sea-level rise is the behavior of the Greenland and Antarctic ice sheets, both of which are pouring billions of tons of ice into the ocean each year.

Recent satellite studies have found that ice loss in both places is speeding up. Antarctica is losing about three times as much ice as it was in the 1990s, while losses in Greenland may be as much as seven times higher than they were in previous decades.

Investigating the processes driving the accelerations — and then using that knowledge to fine-tune predictions of future sea-level rise — is a key priority for 2020 and beyond, according to Marco Tedesco, an ice sheet expert at Columbia University.

"How do we connect the physical processes that we do understand are creating this acceleration from Greenland and Antarctica, very likely over the next decade, to sea-level rise impacts?" he asked E&E News. "And how do we account for the potential shocks of the things that we cannot anticipate still?"

Some scientists worry that as ice loss continues to speed up in both Greenland and Antarctica, parts of the ice sheets could eventually destabilize and collapse entirely — leading to catastrophic sea-level rise.

In recent years, scientists have discovered that warm ocean currents are helping to melt some glaciers from the bottom up, both in Greenland and particularly in parts of West Antarctica. Better understanding the relationship between oceans and ice is a key priority for glacier experts, Tedesco said.

At the same time, monitoring the way water melts and moves along the top of the ice is also a major priority. In Greenland, climate-driven changes in the behavior of large air currents like the jet stream may be helping to drive more surface melting.

"The important thing is to understand how Greenland mass loss can be connected to the recent changes in the atmospheric circulation that we are witnessing," Tedesco said.

Extreme weather events

The past decade saw leaps and bounds in a field of climate research known as "attribution science" — the connection between climate change and extreme weather events.

It was once thought to be impossible, but scientists are now able to estimate the influence of global warming on individual events, like heat waves or hurricanes. In the past few years alone, scientists have found that some events are now occurring that would have been impossible in a world with no human-caused climate change.

As attribution science has advanced, researchers have been able to tackle increasingly complex events, like hurricanes and wildfires, which were previously too complicated to evaluate with any confidence. They've gotten faster, too — researchers are now able to assess some extreme events nearly in real time.

Some organizations are working to develop sophisticated attribution services, similar to weather services, which would release analyses of extreme events as soon as they occur. The German national weather service; the United Kingdom's Met Office; and the Copernicus program, part of the European Centre for Medium-Range Weather Forecasts, have all begun exploring these kinds of projects.

At the same time, scientists are working to improve their predictions of future extreme events in a warming world.

So far, climate models predict that many extreme weather events will happen more frequently, or will become more severe, as the climate continues to change. Heat waves will be hotter, hurricanes will intensify, heavy rainfall events may happen more frequently in some places, and droughts may be longer in others.

Continuing to improve these kinds of predictions — and then communicating them in useful ways to communities that will be affected by them — is a major priority, according to Piers Forster, director of the Priestley International Centre for Climate at the University of Leeds.

There's often great uncertainty when it comes to predicting extreme weather events, he noted — different climate models sometimes deliver vastly different results. But it can often be both expensive and time-consuming to run the models enough times, and at high enough resolutions, to investigate and narrow these uncertainties.

Tackling this issue is one of the key challenges for climate modeling in the coming years, Forster said, noting that "we need to get clever about how we use models to make projections and how we test them."

Projecting the future

Predicting how much the Earth will warm, given a certain level of greenhouse gas emissions, may seem like the simplest goal of climate modeling. But it's harder than it sounds.

Climate models don't always agree on the Earth's exact sensitivity to greenhouse gas emissions — although they do tend to fall within a certain range. If global carbon dioxide concentrations were to double, for instance, models from the past decade have tended to predict that the Earth would warm from between 1.5 and 4.5 degrees Celsius.

Scientists around the world are working on a new suite of updated climate models, which will be used to inform future reports produced by the Intergovernmental Panel on Climate Change. But there's one issue that's already raising eyebrows, according to Zeke Hausfather, a climate scientist at the University of California, Berkeley — so far, the newer models seem to be predicting a much higher climate sensitivity than the older models.

"The high end is much higher," he told E&E News. "There's a number of models above 4.8 degrees sensitivity and even up to 5.6."

Only about 20 new models have submitted results; far more will come pouring in before the project is complete. And as Hausfather pointed out, other recent studies have suggested that the Earth's climate sensitivity might actually be narrower than the old models suggested.

But it's something to keep in mind at a time when accurate predictions about future warming are more pressing than ever.

"The fact that some of these models are high is interesting but doesn't necessarily mean we should believe them over other lines of evidence," Hausfather said. "It just reflects the fact that climate sensitivity is this huge remaining source of uncertainty in our climate projections."

At the same time, climate modelers are also working to hone their projections in other ways. Models are able to capture increasingly complex processes the more they advance. But there are still a few key areas scientists are focused on improving.

Clouds, for instance, are believed to have a significant influence on the climate system. But they're notoriously difficult to reproduce in climate models. Certain aspects of the carbon cycle are also underrepresented in models, Hausfather noted — for instance, the way that forests and oceans absorb or release greenhouse gases into the atmosphere.

And scientists are also working to develop more realistic climate scenarios for their modeling projects. In the past, many studies have focused on a "business as usual" climate scenario, which suggests high rates of future greenhouse gas emissions, the continued expansion of coal, and other assumptions about industry and socioeconomics that may no longer be realistic, according to Hausfather.

While global climate action is still significantly lagging when it comes to meeting the goals of the Paris climate agreement, the future may not be as dire as previous business-as-usual climate studies would suggest. Focusing new studies on more realistic scenarios may be more useful to policymakers and communities trying to plan for the future.

"In many ways the range of possible futures is narrowing," Hausfather said. "As we get closer to 2100 and as the world takes more climate action, the worst-case 4 degrees-plus warming scenarios are a lot less likely."

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at  www.eenews.net .

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Climate Change FAQs

You asked. Our scientists answered. Use this guide to have the best info about climate change and how we can solve it together.

December 09, 2018 | Last updated November 13, 2023

Top Question: What Can I Do About Climate Change?

• Start a conversation. Talking about climate change is the best way to kickstart action , says Chief Scientist Kath arine Hayhoe.
• Vote at the ballot box (and the store). At every level, elected leaders have influence on policies that affect us all. And support companies taking climate action.
• Take personal action. Calculate your carbon footprint and share what you’ve learned to make action contagious.

Climate Change Basics

Click items to expand answers.

Each of these terms describes parts of the same problem—the fact that the average temperature of Earth is rising. As the planet heats up (global warming), we see broad impacts on Earth’s climate, such as shifting seasons, rising sea level, and melting ice.

As the impacts of climate change become more frequent and more severe, they will create—and in many cases they already are creating—crises for people and nature around the world. Many types of extreme weather, including heatwaves, heavy downpours, hurricanes and wildfires are becoming stronger and more dangerous.

Left unchecked, these impacts will spread and worsen, affecting our homes and cities, economies, food and water supplies as well as the species, ecosystems, and biodiversity of this planet we all call home.

All of these terms are accurate, and there’s no perfect one that will make everyone realize the urgency of action. Whatever you choose to call it, the most important thing is that we act to stop it.

Yes, scientists agree that the warming we are seeing today is entirely human-caused.

Climate has changed in the past due to natural factors such as volcanoes, changes in the sun’s energy and the way the Earth orbits the sun.  In fact, these natural factors should be cooling the planet. However, our planet is warming.

Scientists have known for centuries that the Earth has a natural blanket of greenhouse or heat-trapping gases. This blanket keeps the Earth more than 30 degrees Celsius (over 60 degrees Fahrenheit) warmer than it would be otherwise. Without this blanket, our Earth would be a frozen ball of ice.

Greenhouse gases, which include carbon dioxide and methane, trap some of the Earth’s heat that would otherwise escape to space. The more heat-trapping gases in the atmosphere, the thicker the blanket and the warmer it gets.

Over Earth’s history, heat-trapping gas levels have gone up and down due to natural factors. Today, however, by burning fossil fuels, causing deforestation ( forests are key parts of the planet’s natural carbon management systems), and operating large-scale industrial agriculture, humans are rapidly increasing levels of heat-trapping gases in the atmosphere.

The human-caused increase in carbon dioxide in the atmosphere is much greater than any observed in the paleoclimate history (i.e. ancient climate data measured through ice sheets, tree rings, sediments and more) of the earth. As a result, temperature in the air and ocean is now increasing faster than at any time in human history.

Scientists have looked at every other possible reason why climate might be changing today, and their conclusions are clear. There’s no question: it’s us.

One of the main reasons scientists are so worried about climate change is the speed at which it is occurring. In many cases, these changes are happening faster than animals, plants, and ecosystems can safely adapt to – and the same is true for human civilization.

We’ve never seen climate change this quickly, and it is putting our food and water systems, our infrastructure, and even our economies at risk. In some places, these changes are already crossing safe levels for ecosystems and humans.

That’s why, the more we do to mitigate these risks, the better off we will all be.

Effects of Climate Change

Climate change is affecting our planet in many ways. Average temperatures are increasing; rainfall patterns are shifting; snow lines are retreating; glaciers and ice sheets are melting; permafrost is thawing; sea levels are rising ; and severe weather is becoming more frequent.

In particular, heatwaves are becoming more frequent and more intense. Tropical cyclones like hurricanes, typhoons, and cyclones are intensifying faster and dumping more rain. Wildfires are burning greater area, and in many areas around the world, heavy rainfall is becoming more frequent and droughts are getting stronger.

All of these impacts are concerning because they can harm and even potentially lead to the collapse of ecosystems and human systems. And it’s clear that they become more severe  the more heat-trapping gases we produce.

Rapid changes in climate can directly and indirectly impact animals across the world. Many species are approaching—or have already reached—the limit of where they can go to find hospitable climates. In the polar regions, animals like polar bears that live on sea ice are now struggling to survive as that ice melts.

It’s not just how climate change affects an animal directly; it’s about how the warming climate affects the ecosystem and food chain to which an animal has adapted. For example, in the U.S. and Canada, moose are being affected by an increase in ticks and parasites that are surviving the  shorter, milder winters .

In western North America, salmon rely on steady-flowing cold rivers to spawn. As climate change alters the temperature and flow of these waterways, some salmon populations are dwindling. This change in salmon population affects many species that rely on salmon like orcas or grizzly bears.

Changes in temperature and moisture are causing some species to migrate in search of new places to live. For instance, in North America, species are shifting their ranges an average of 11 miles north and 36 feet higher in elevation each decade to find more favorable conditions. The Central Appalachians are one resilient climate escape route  that may help species adapt to changing conditions.

There are some natural places with enough topographical diversity such that, even as the planet warms, they can be  resilient strongholds for plant and animal species . These strongholds serve as breeding grounds and seed banks for many plants and animals that otherwise may be unable to find habitat due to climate change. However, strongholds are not an option for all species, and some plants and animals are blocked from reaching these areas by human development like cities, highways and farmland.

Here at The Nature Conservancy, we use science to identify such locations and work with local partners and communities to do everything we can to protect them.

From reducing agricultural productivity to threatening livelihoods and homes, climate change is affecting people everywhere. You may have noticed how  weather patterns near you are shifting  or how more frequent and severe storms are developing in the spring. Maybe your community is experiencing more severe flooding or  wildfires .

Many areas are even experiencing “sunny day flooding” as rising sea levels cause streets to flood during high tides. In Alaska, some entire coastal communities are being moved because the sea level has risen and what used to be permanently frozen ground has thawed to the point where their original location is no longer habitable.

Climate change also  exacerbates the threat of human-caused conflict  resulting from a scarcity of resources like food and water that become less reliable as growing seasons change and rainfall patterns become less predictable.

Many of these impacts are disproportionately affecting low-income, Indigenous, or marginalized communities. For example, in large cities in North America, low-income communities are often hotter during heatwaves, more likely to flood during heavy downpours, and the last to have their power restored after storms.

Around the globe, many of the poorest nations are being impacted first and most severely by climate change, even though they have contributed far less to the carbon pollution that has caused the warming in the first place. Climate change affects us all, but it doesn’t affect us all equally: and that’s not fair.

Whether you live close to a coast or far from one, what happens in oceans matters to our lives .

Earlier, we described how greenhouse gases trap heat around the planet. Only a small fraction of the extra heat being trapped by the carbon pollution blanket is going into heating up the atmosphere. Almost 90% of the heat is going into the ocean, causing the ocean to warm.

Warmer water takes up more space, causing sea level to rise. As land-based ice melts, this addition of water from land to the ocean causes the ocean to rise even faster.

Warmer oceans can drive fish migrations and lead to coral bleaching and die off.

As the ocean surface warms, it’s less able to mix with deep, nutrient-rich water, which limits the growth of phytoplankton (little plants that serve as the base of the marine food web and that also produce a lot of the oxygen we breathe). This in turn affects the whole food chain.

In addition to taking up heat, the oceans are also absorbing about a quarter of the carbon pollution that humans produce. In addition to warming the air and water of our planet, some of this extra carbon dioxide is being absorbed by the ocean, making our oceans more acidic. In fact, the rate of ocean acidification is the highest it has been in 300 million years!

This acidification negatively impacts many marine habitats and animals, but is a particular threat to shellfish, which struggle to grow shells as water becomes more acidic.

There’s also evidence that warming surface waters may contribute to slowing ocean currents. These currents act like a giant global conveyor belt that transports heat from the tropics toward the poles. This conveyor belt is critical for bringing nutrient-rich waters towards the surface near the poles where giant blooms of food web-supporting phytoplankton occur (this is why the Arctic and Antarctic are known for having such high abundance of fish and marine mammals). With continued warming, these processes may be at risk.

Climate change is disrupting weather patterns, leading to more extreme and frequent heatwaves, droughts, and flooding events that directly threaten harvests. Warmer seasons are also contributing to rising populations of insect pests that eat a higher share of crop yields, and higher carbon dioxide levels are causing plants to grow faster, while decreasing their nutritional content.

Flooding, drought, and heatwaves have decimated crops in China. In Bangladesh, rising sea levels are threatening rice crops. In the midwestern United States, more frequent and intense rains have caused devastating spring flooding, which delays—and sometimes prevents—planting activities.

These impacts make it more difficult for farmers to grow crops and sustain their livelihoods. Globally, one recent study finds that staple crop yield failures will be 4.5 times higher by 2030 and 25 times higher by mid-century. That means a major rice or wheat failure every other year, and higher probabilities of soybean and maize failures.

However, farmers are poised to play a significant role in addressing climate change. Agricultural lands are among the Earth’s largest natural reservoirs of carbon , and when farmers use soil health practices like cover crops, reduced tillage, and crop rotations, they can draw carbon out of the atmosphere .

These practices also help to improve the soil’s water-holding capacity, which is beneficial as water can be absorbed from the soil by crops during times of drought, and during heavy rainfalls, soil can help reduce flooding and run-off by slowing the release of water into streams.

Healthier soils can also improve crop yields, boost farmers’ profitability, and reduce erosion and fertilizer runoff from farm fields, which in turn means cleaner waterways for people and nature. That’s why climate-smart agriculture is a win-win!

Solutions to Climate Change

Yes, deforestation, land use change, and agricultural emissions are responsible for about a quarter of heat-trapping gas emissions from human activities. Agricultural emissions include methane from livestock digestion and manure, nitrous oxide from fertilizer use, and carbon dioxide from land use change.

Forests are one of our most important types of natural carbon storage , so when people cut down forests, they lose their ability to store carbon. Burning trees—either through wildfires or controlled burns-- releases even more carbon into the atmosphere.

Forests are some of the best natural climate solutions we have on this planet. If we can slow or stop deforestation , manage natural land so that it is healthy, and use other natural climate solutions such as climate-smart agricultural practices, we could achieve up to one third of the emission reductions needed by 2030 to keep global temperatures from rising more than 2°C (3.6°F). That’s the equivalent of the world putting a complete stop to burning oil.

When it comes to climate change, there’s no one solution that will fix it all. Rather, there are many solutions that, together, can address this challenge at scale while building a safer, more equitable, and greener world.

First, we need to reduce our heat-trapping gas emissions as much as possible, as soon as possible. Through efficiency and behavioral change, we can reduce the amount of energy we need.

At the same time, we have to  transition all sectors of our economy away from fossil fuels  that emit carbon, through increasing our use of clean energy sources like wind and solar. This transition will happen much faster and more cost-effectively if governments enact an economy-wide price on carbon.

Second, we need to harness the power of nature to capture carbon and deploy agricultural practices and technologies that capture and store carbon. Our research shows that proper land management of forests and farmlands, also called natural climate solutions, can provide up to one-third of the emissions reductions necessary to reach the Paris Climate Agreement’s goal.

The truth, however, is that even if we do successfully reach net zero carbon emissions by 2050, we will still have to address harmful climate impacts. That’s why there is a third category of climate solutions that is equally important: adaptation to the impacts of global warming.

Adaptation consists of helping our human and natural systems prepare for the impacts of a warming planet. Greening urban areas helps protect them from heat and floods; restoring coastal wetlands helps protect from storm surge; increasing the diversity of ecosystems helps them to weather heat and drought; growing super-reefs helps corals withstand marine heatwaves. There are many ways we can use technology, behavioral change, and nature to work together to make us more resilient to climate impacts.

Climate change affects us all, but it doesn’t affect us all equally or fairly. We see how sea level rise threatens communities of small island states like Kiribati and the Solomon Islands and of low-lying neighborhoods in coastal cities like Mumbai, Houston and Lagos. Similarly, people living in many low-income neighborhoods in urban areas in North America are disproportionately exposed to heat and flood risk due to a long history of racist policies like redlining.

Those who have done the least to contribute to this problem often bear the brunt of the impacts and have the fewest resources to adapt. That’s why it is particularly important to help vulnerable communities adapt and become more resilient to climate change.

We need to  increase renewable energy at least nine-fold  from where it is today to meet the goals of the Paris Agreement and avoid the worst climate change impacts. Every watt that we can reduce through efficiency or shift from fossil fuel to renewables like wind power or solar power is a step in the right direction.

The best science we have tells us that to avoid the worst impacts of global warming, we must globally achieve net-zero carbon emissions no later than 2050. To do this, the world must immediately identify pathways to reduce carbon emissions from all sectors: transportation, agriculture, electricity, and industry. This cannot be achieved without a major shift to renewable energy.

Clean energy and technological innovation are not only helping mitigate climate change, but also helping create jobs and support economic growth in communities across the world. Renewable energy such as wind and solar have experienced remarkable growth and huge cost improvements over the past decade with no signs of slowing down.

Prices are declining rapidly, and renewable energy is becoming increasingly competitive with fossil fuels all around the world. In some places, new renewable energy is already cheaper than continuing to operate old, inefficient, and dirty fossil fuel-fired power plants.

However, it’s important that renewable energy development isn’t built at the expense of protecting unique ecosystems or important agricultural lands. Without proactive planning, renewable energy developments could displace up to 76 million acres of farm and wildlife habitat—an area the size of Arizona.

Fortunately, TNC studies have found that  we can meet clean energy demand 17 times over  without converting more natural habitat. The key is to deploy new energy infrastructure on the wealth of previously converted areas such as agricultural lands, mine sites, and other transformed terrain, at a  lower cost .

Thoughtful planning is required at every step. For instance, much of the United States’ wind potential is in the Great Plains, a region with the best remaining grassland habitat on the continent. TNC has mapped out the right places to site wind turbines  in this region in order to catalyze renewable energy responsibly, and we’re doing the same analysis for India and Europe as well.

There can also be unique interventions to protect wildlife where clean energy has already been developed. In Kenya, for instance, a wind farm employs biodiversity monitors to watch for migrating birds , and can order individual turbines to shut down in less than a minute.

The Nature Conservancy is committed to tackling the dual crises of climate change and biodiversity loss. These two crises are, as our chief scientist says, two sides of the same coin .

What we do between now and 2030 will determine if we get on track to meet the targets of the Paris Agreement while also conserving enough land and water to slow accelerated species loss. That’s why we have ambitious 2030 goals that focus on people and the planet.

We're combatting these dual crises by:

• Enhancing nature’s ability to draw down and store carbon across forests, farmlands and wetlands by  accelerating the deployment of natural climate solutions .
• Mobilizing action for a clean energy future  and new, low-carbon technologies in harmony with nature.
• Supporting the leadership of Indigenous Peoples and local communities .
• Building resilience through natural defenses such as restored reefs, mangroves and wetlands that reduce the impact of storms and floods.
• Restoring and bolstering the resilience of vulnerable ecosystems like coral reefs and coastal wetlands.
• Helping countries around the globe, like India and Croatia , implement and enhance their commitments to the Paris Agreement.

Visit  Our Goals for 2030  to learn more about TNC’s actions and partnerships to tackle climate change this decade.

Why We Must Urgently Act on Climate

Some amount of change has already occurred, and some future changes are inevitable due to our past choices. However, the good news is that we know what causes it and what to do to stop it. It will take courage, ambition, and a push to create change, but it can be done.

Reaching net zero carbon emissions by 2050 is an ambitious goal, one that’s going to require substantial effort across every sector of the economy. We don’t have a lot of time, but if we are prepared to act now, and act together, we can substantially reduce the rate of global warming and prevent the worst impacts of climate change from coming to pass.

The even better news is that the low carbon economy that we need to create will also give us cleaner air, more abundant food and water, more affordable energy choices, and safer cities. Likewise, many of the solutions to even today’s climate change impacts benefit both people and nature.

When we really understand the benefits of climate action—how it will lead us to a world that is safer and healthier, more just and equitable—the only question we have left is: What are we waiting for?

Scientific studies show that climate change, if unchecked, would overwhelm our communities and pose an existential threat to certain ecosystems.

These catastrophic impacts include sea level rise from melting ice sheets in Greenland and Antarctica that would flood most major global coastal cities; increasingly common and more severe storms, droughts, and heatwaves; massive crop failures and water shortages; and the large-scale destruction of habitats and ecosystems, leading to species extinctions .

To avoid the worst of climate change, the Intergovernmental Panel on Climate Change (IPCC) says that “every bit of warming matters.” When it comes to limiting climate change, there’s no magic threshold: the faster we reduce our emissions, the better off we will be.

In 2015, all the countries in the world came together and signed the Paris Agreement . It’s a legally binding international treaty in which signatories agree to hold “the increase in the global average temperature to well below 2°C (3.5° F) above pre-industrial levels” and pursue efforts “to limit the temperature increase to 1.5°C (2.7°F) above pre-industrial levels.”

Every day that goes by, we are releasing carbon into the atmosphere and increasing our planetary risk. Scientists agree that we need to begin reducing carbon emissions  RIGHT NOW .

To reach the goal of the Paris Agreement, the world must make significant progress toward decarbonization (reducing carbon from the atmosphere and replacing fossil fuels in our economies) by 2030 and commit ourselves to reaching net zero carbon emissions by 2050. This is no small feat and will require a range of solutions applied together, to reach the goal.

As the IPCC says, “every action matters.” You can be part of the climate change solution and you can activate others, too.

It’s really important that we use our voices for climate action.  Tell your policy makers that you care about climate change  and want to see them enact laws and policies that address greenhouse gas emissions and climate impacts.

One of the simplest—and most important—things that everyone can do is to  talk about climate change with family and friends . We know these conversations can seem like a recipe for discord and hard feelings. It starts with meeting people where they are. TNC has resources to help you break the climate silence and pave the way for action on global warming.

You can also talk about climate change where you work, and with any other organization you’re part of. Join an organization that shares your values and priorities, to help amplify your voice. Collective change begins with understanding the risks climate change poses and the actions that can be taken together to reduce emissions and build resilience.

Lastly, you can calculate your carbon footprint  and take actions individually or with your family and friends to lower it. You might be surprised which of your activities are emitting the most heat-trapping gases. But don’t forget to talk about the changes you’ve made, to help make them contagious —contagious in a good way, of course!

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Talking About Climate

COP28: Your Guide to the 2023 UN Climate Change Conference in UAE

COP28 takes place November 30-December 12, 2023 in United Arab Emirates. This guide will tell you what to expect at COP28, why TNC will be there, and what it all means for you.

Food, Climate and Nature FAQs: Understanding the Food System’s Role in Healing Our Planet

You've got questions about food, farming, climate and nature. We've got answers and easy ways you can support regenerative food systems that help the planet.

Renewable Energy Transition

We no longer need to choose between abundant energy and a cleaner environment. A renewable energy revolution is happening across the globe.

ENCYCLOPEDIC ENTRY

Global warming.

The causes, effects, and complexities of global warming are important to understand so that we can fight for the health of our planet.

Earth Science, Climatology

Tennessee Power Plant

Ash spews from a coal-fueled power plant in New Johnsonville, Tennessee, United States.

Photograph by Emory Kristof/ National Geographic

Global warming is the long-term warming of the planet’s overall temperature. Though this warming trend has been going on for a long time, its pace has significantly increased in the last hundred years due to the burning of fossil fuels . As the human population has increased, so has the volume of fossil fuels burned. Fossil fuels include coal, oil, and natural gas, and burning them causes what is known as the “greenhouse effect” in Earth’s atmosphere.

The greenhouse effect is when the sun’s rays penetrate the atmosphere, but when that heat is reflected off the surface cannot escape back into space. Gases produced by the burning of fossil fuels prevent the heat from leaving the atmosphere. These greenhouse gasses are carbon dioxide , chlorofluorocarbons, water vapor , methane , and nitrous oxide . The excess heat in the atmosphere has caused the average global temperature to rise overtime, otherwise known as global warming.

Global warming has presented another issue called climate change. Sometimes these phrases are used interchangeably, however, they are different. Climate change refers to changes in weather patterns and growing seasons around the world. It also refers to sea level rise caused by the expansion of warmer seas and melting ice sheets and glaciers . Global warming causes climate change, which poses a serious threat to life on Earth in the forms of widespread flooding and extreme weather. Scientists continue to study global warming and its impact on Earth.

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For scientists at SERC, global warming is more than an idea. It is a reality they have seen and felt. The decade from 2001 to 2010 was the warmest decade on record, and while not all places are feeling the heat equally, on average the temperature of the Earth is climbing.

Around the globe, SERC scientists have watched plants and animals move to new territory as regions grow warmer. Closer to home, they have seen evidence of global warming on SERC’s Maryland campus. Since 1987, the growing season at SERC has become a week longer, enabling the trees to grow larger and faster .

The science is simple: Carbon dioxide and other greenhouse gases trap energy from the sun. As greenhouse gases in the atmosphere continue to spike, more heat energy from the sun remains trapped in the lower atmosphere, where it warms the planet below. Since the Industrial Revolution, the global average temperature has risen by almost 1° Celsius . If nothing changes, by 2100 that figure is likely to pass 2° Celsius, enough to melt ice sheets, drown island communities and strain the water supply of billions of people.

SERC researchers investigate how environments are reacting to global warming now, and how they may respond in the future. For decades, they have tracked the swelling of trees in SERC forests and the northward migration of Florida’s tropical mangroves, no longer held back by winter cold snaps. They have uncovered the possibility of dead zones expanding as oceans warm. They’ve also set up warming experiments to examine how various plants and microbes will behave in a future, warmer climate. Explore the projects below to learn more about their work.

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Nutrient over-enrichment increases the productivity of scrub mangroves, but also decreases their resistance and resilience to hurricane damage.

Nutrient Enrichment Intensifies Hurricane Impact on Mangroves

Warming and elevated CO 2 experiment in the Global Change Research Wetland. Heat lamps warm the plants from above, while cables heat the soil.

Salt Marsh Accretion Response to Temperature eXperiment (SMARTX)

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Causes and Effects of Climate Change

Fossil fuels – coal, oil and gas – are by far the largest contributor to global climate change, accounting for over 75 per cent of global greenhouse gas emissions and nearly 90 per cent of all carbon dioxide emissions.

As greenhouse gas emissions blanket the Earth, they trap the sun’s heat. This leads to global warming and climate change. The world is now warming faster than at any point in recorded history. Warmer temperatures over time are changing weather patterns and disrupting the usual balance of nature. This poses many risks to human beings and all other forms of life on Earth.

Causes of Climate Change

Generating power

Generating electricity and heat by burning fossil fuels causes a large chunk of global emissions. Most electricity is still generated by burning coal, oil, or gas, which produces carbon dioxide and nitrous oxide – powerful greenhouse gases that blanket the Earth and trap the sun’s heat. Globally, a bit more than a quarter of electricity comes from wind, solar and other renewable sources which, as opposed to fossil fuels, emit little to no greenhouse gases or pollutants into the air.

Manufacturing goods

Manufacturing and industry produce emissions, mostly from burning fossil fuels to produce energy for making things like cement, iron, steel, electronics, plastics, clothes, and other goods. Mining and other industrial processes also release gases, as does the construction industry. Machines used in the manufacturing process often run on coal, oil, or gas; and some materials, like plastics, are made from chemicals sourced from fossil fuels. The manufacturing industry is one of the largest contributors to greenhouse gas emissions worldwide.

Cutting down forests

Cutting down forests to create farms or pastures, or for other reasons, causes emissions, since trees, when they are cut, release the carbon they have been storing. Each year approximately 12 million hectares of forest are destroyed. Since forests absorb carbon dioxide, destroying them also limits nature’s ability to keep emissions out of the atmosphere. Deforestation, together with agriculture and other land use changes, is responsible for roughly a quarter of global greenhouse gas emissions.

Using transportation

Most cars, trucks, ships, and planes run on fossil fuels. That makes transportation a major contributor of greenhouse gases, especially carbon-dioxide emissions. Road vehicles account for the largest part, due to the combustion of petroleum-based products, like gasoline, in internal combustion engines. But emissions from ships and planes continue to grow. Transport accounts for nearly one quarter of global energy-related carbon-dioxide emissions. And trends point to a significant increase in energy use for transport over the coming years.

Producing food

Producing food causes emissions of carbon dioxide, methane, and other greenhouse gases in various ways, including through deforestation and clearing of land for agriculture and grazing, digestion by cows and sheep, the production and use of fertilizers and manure for growing crops, and the use of energy to run farm equipment or fishing boats, usually with fossil fuels. All this makes food production a major contributor to climate change. And greenhouse gas emissions also come from packaging and distributing food.

Powering buildings

Globally, residential and commercial buildings consume over half of all electricity. As they continue to draw on coal, oil, and natural gas for heating and cooling, they emit significant quantities of greenhouse gas emissions. Growing energy demand for heating and cooling, with rising air-conditioner ownership, as well as increased electricity consumption for lighting, appliances, and connected devices, has contributed to a rise in energy-related carbon-dioxide emissions from buildings in recent years.

Consuming too much

Your home and use of power, how you move around, what you eat and how much you throw away all contribute to greenhouse gas emissions. So does the consumption of goods such as clothing, electronics, and plastics. A large chunk of global greenhouse gas emissions are linked to private households. Our lifestyles have a profound impact on our planet. The wealthiest bear the greatest responsibility: the richest 1 per cent of the global population combined account for more greenhouse gas emissions than the poorest 50 per cent.

Based on various UN sources

Effects of Climate Change

Hotter temperatures

As greenhouse gas concentrations rise, so does the global surface temperature. The last decade, 2011-2020, is the warmest on record. Since the 1980s, each decade has been warmer than the previous one. Nearly all land areas are seeing more hot days and heat waves. Higher temperatures increase heat-related illnesses and make working outdoors more difficult. Wildfires start more easily and spread more rapidly when conditions are hotter. Temperatures in the Arctic have warmed at least twice as fast as the global average.

More severe storms

Destructive storms have become more intense and more frequent in many regions. As temperatures rise, more moisture evaporates, which exacerbates extreme rainfall and flooding, causing more destructive storms. The frequency and extent of tropical storms is also affected by the warming ocean. Cyclones, hurricanes, and typhoons feed on warm waters at the ocean surface. Such storms often destroy homes and communities, causing deaths and huge economic losses.

Increased drought

Climate change is changing water availability, making it scarcer in more regions. Global warming exacerbates water shortages in already water-stressed regions and is leading to an increased risk of agricultural droughts affecting crops, and ecological droughts increasing the vulnerability of ecosystems. Droughts can also stir destructive sand and dust storms that can move billions of tons of sand across continents. Deserts are expanding, reducing land for growing food. Many people now face the threat of not having enough water on a regular basis.

A warming, rising ocean

The ocean soaks up most of the heat from global warming. The rate at which the ocean is warming strongly increased over the past two decades, across all depths of the ocean. As the ocean warms, its volume increases since water expands as it gets warmer. Melting ice sheets also cause sea levels to rise, threatening coastal and island communities. In addition, the ocean absorbs carbon dioxide, keeping it from the atmosphere. But more carbon dioxide makes the ocean more acidic, which endangers marine life and coral reefs.

Loss of species

Climate change poses risks to the survival of species on land and in the ocean. These risks increase as temperatures climb. Exacerbated by climate change, the world is losing species at a rate 1,000 times greater than at any other time in recorded human history. One million species are at risk of becoming extinct within the next few decades. Forest fires, extreme weather, and invasive pests and diseases are among many threats related to climate change. Some species will be able to relocate and survive, but others will not.

Not enough food

Changes in the climate and increases in extreme weather events are among the reasons behind a global rise in hunger and poor nutrition. Fisheries, crops, and livestock may be destroyed or become less productive. With the ocean becoming more acidic, marine resources that feed billions of people are at risk. Changes in snow and ice cover in many Arctic regions have disrupted food supplies from herding, hunting, and fishing. Heat stress can diminish water and grasslands for grazing, causing declining crop yields and affecting livestock.

More health risks

Climate change is the single biggest health threat facing humanity. Climate impacts are already harming health, through air pollution, disease, extreme weather events, forced displacement, pressures on mental health, and increased hunger and poor nutrition in places where people cannot grow or find sufficient food. Every year, environmental factors take the lives of around 13 million people. Changing weather patterns are expanding diseases, and extreme weather events increase deaths and make it difficult for health care systems to keep up.

Poverty and displacement

Climate change increases the factors that put and keep people in poverty. Floods may sweep away urban slums, destroying homes and livelihoods. Heat can make it difficult to work in outdoor jobs. Water scarcity may affect crops. Over the past decade (2010–2019), weather-related events displaced an estimated 23.1 million people on average each year, leaving many more vulnerable to poverty. Most refugees come from countries that are most vulnerable and least ready to adapt to the impacts of climate change.

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City Sprawl Now Large Enough to Sway Global Warming Over Land

Urban land now reaches farther than ever, and so too does its influence on global warming

Cities have grown quite a lot in recent decades—global urban land cover has swelled by 226 percent since 1992. As city sprawl expands its reach, its influence on the world's climate grows in tandem. 

(Image by Pedro Kümmel |  Unsplash.com)

RICHLAND, Wash.— Just how much heat does city sprawl add to large-scale warming? That’s one longstanding question researchers sought to answer in a new study recently published in the journal One Earth. 

Once thought to cover too little of the Earth’s surface to affect climate at larger scales, the new work suggests that urbanization does indeed have a detectable influence on global warming over land , with more to potentially follow as cities continue growing. 

The effect is most dramatic in some of the world’s most rapidly urbanizing areas. In the bustling Yangtze River Basin, for example, home to more than 480 million people (one third of China’s total population), urban sprawl contributed nearly 40 percent of the area’s increased warming between 2003 and 2019. 

In Japan, where close to 10 percent of total land is developed, urbanization contributed a quarter of the added warming observed during the study period. The urban signal was less pronounced in Europe and North America, where urbanization boosted roughly 2 – 3 percent of warming. That’s likely because much of the development there happened before the study period and, proportionally, there is still a great deal of undeveloped land compared to other smaller regions and countries. 

Overall, cities added just over one percent of increased land surface warming across the entire globe; 1.3 percent during daytime and 1.1 percent during nighttime.

“Urbanization” is an umbrella term of sorts. It encompasses not only built structures in cities, but also the many climate-influencing factors like air pollution, city parks and swelling populations that are tied to their existence.

The urban climate signal

Traditionally, cities are either left out of global climate models or represented in very simplistic ways, according to the study authors. When climate scientists use these models to understand how extreme weather may change in a warmer world , for example, they rarely factor cities into their simulations. But if they’re included at all, cities aren’t depicted as growing, changing entities, even though the rest of the world is projected to change decades into the future.

That’s a shortcoming, said lead author and Earth scientist TC Chakraborty at the Department of Energy’s Pacific Northwest National Laboratory . A large body of research demonstrates that cities influence the climate around us in a myriad of ways.

Buildings absorb and trap heat, which means cities take much longer to warm and cool down than rural areas. In some cases, this could mean city dwellers may spend more time in uncomfortable heat than their countryside neighbors . Cityscapes can change the way air moves around us, or even intensify extreme weather . 

While the influence of urban land has been clear at the local scale, researchers have questioned whether cities matter at the regional, continental and planetary scales.

“The answer is yes, they do; to a small extent,” said Chakraborty. “Urbanization does have a detectable impact on global land warming. That impact is minor but statistically significant at the global land scale, and particularly evident at continental scales. When you zoom into specific regions of the world, the effects can get quite large.”

It depends on where you look, Chakraborty added. In the case of Greenland, where very little urban land was added during the study period, city sprawl didn’t pose much of an impact on large-scale warming. But in rapidly urbanizing areas like certain parts of Asia, the authors saw strong, large-scale warming that stemmed from urbanization.

Although cities have grown sufficiently large to affect the global climate, their effect remains small when compared to that of greenhouse gas emissions and other anthropogenic changes. The new findings counter a common point of skepticism, said Chakraborty.

“Some argue that the urban heat island effect is a dominant contributor to large-scale climate warming. Our findings demonstrate that this is untrue: the impact of the urban heat island on global land warming is statistically significant, but it’s far from the major contributor. Our population-scale estimate of this warming using satellite data effectively demonstrates that,” said Chakraborty.

Moreover, the urban effect on climate is complex, he added. Earlier this year, Chakraborty and other PNNL researchers showed that one arid desert city partly cooled as it developed . They found that adding more parks and farmland than is naturally possible in an arid background climate helped the city to partially buck the global warming trend. 

The authors observed a similar effect in the new work, finding that India and Africa, the latter including many arid cities, showed daytime urban cooling signals as cities developed. In India’s case, said Chakraborty, this is a combination of irrigation in rural areas that modulate the urban-rural temperature difference, as well as the additional emission of atmospheric aerosols from cities. 

City sprawl on the rise 

Between 1992 and 2019, global urban land cover climbed by 226 percent. That amounts to roughly 448,113 square kilometers of urbanized land added in under three decades , far surpassing the amount of city growth that happened in the entire century preceding the study period . Imagine every inch of California were developed as a city; that still falls just shy of capturing all the urban land added within that time span.

Most of this growth sprang up in Asia. The United States expanded its urbanized area by 181 percent, India by 366 percent, and China by 413 percent. Among countries with the most urban area, China and the U.S. demonstrated the largest urban area growth. 

As the human population continues ballooning, the majority are expected to live in cities. This means improved urban representation in climate models will only grow more important as researchers seek to better simulate regional climate change, especially when they do so with an aim to inform mitigation and adaptation strategies.

“ People are using climate models more and more for regional-scale assessments, with many plans to run global models at finer and finer resolutions as our computational capabilities improve, ” said Chakraborty. “ When you start doing that—going down to the regional scale—you need representation of urban areas and their impacts on regional-scale temperature, cloud cover, precipitation, and air pollution. ”

By incorporating city sprawl into climate models, “ we can improve our ability to better estimate regional heat waves , ” said Chakraborty. Furthermore, “ there is a lot of evidence that urbanization can increase extreme precipitation , but it is difficult to examine this impact using models due to their current coarse representations of urban land and their properties. ”

“Then there are the unknowns,” he added. “Because we have rarely tried to examine the impacts of urbanization on large-scale climate, we have little idea what other urbanization-induced feedbacks are at play, especially when considering changes in thermal, radiative, and aerodynamic properties of urban areas over space and time.”

Satellites are key 

For the most part, large-scale climate assessments have used surface air temperature readings from weather stations as inputs. However, such measurements are prone to sampling bias because surface instruments are often few and far between, only reading the conditions that immediately surround them.

“It is extremely difficult to capture the full heterogeneity of surface climate using these measurements,” said Chakraborty. “Though there have been huge efforts, through both new observation networks and better data assimilation techniques, that have made these estimates more and more reliable over time.”

To address the sampling issue, the authors of the new work instead used satellite-derived estimates of land surface temperature change. Satellite observations take in the bulk temperature of an area by measuring infrared radiation from every pixel of the Earth's surface, removing spatial sampling bias by design.

Researchers at PNNL are working to better incorporate urbanization into climate models, said coauthor and Lab Fellow Yun Qian .

“DOE has recently made significant investments in strengthening its leadership in climate modeling to drive research that can inform the development of resilience technologies to protect America’s diverse communities,” said Qian. “One of those major efforts is to improve urban representation in DOE’s flagship Energy Exascale Earth System Model . Seven national laboratories are collaborating in the E3SM project to develop the most comprehensive representation of the Earth system in a modeling framework and address the most challenging and demanding climate change research imperatives.”

This work was supported by the Department of Energy’s Office of Science.

Pacific Northwest National Laboratory draws on its distinguishing strengths in chemistry , Earth sciences , biology and data science to advance scientific knowledge and address challenges in sustainable energy and national security . Founded in 1965, PNNL is operated by Battelle for the Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, visit https://www.energy.gov/science/ . For more information on PNNL, visit PNNL's News Center . Follow us on Twitter , Facebook , LinkedIn and Instagram .

Published: June 18, 2024

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The warming of the Earth has been the subject of intense debate and concern for many scientists, policy-makers, and citizens for at least the past decade. Climate Change Science: An Analysis of Some Key Questions , a new report by a committee of the National Research Council, characterizes the global warming trend over the last 100 years, and examines what may be in store for the 21st century and the extent to which warming may be attributable to human activity.

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Research signals major milestone in cutting harmful gases that deplete ozone and worsen global warming

by University of Bristol

A new study has revealed significant progress in the drive to reduce levels in the atmosphere of chemicals that destroy Earth's ozone layer, confirming the success of historic regulations limiting their production.

The findings, led by the University of Bristol and published in Nature Climate Change , show for the first time a notable decline in the atmospheric levels of potent ozone-depleting substances (ODS), called hydrochlorofluorocarbons (HCFCs). These HCFCs are also harmful greenhouse gases, so a reduction should also lessen global warming .

The Montreal Protocol was agreed to internationally in 1987 to introduce controls on the production and usage of ODS, which were once widely used in the manufacture of hundreds of products, including refrigerators, aerosol sprays, foams and packaging.

HCFCs were developed as replacements for chlorofluorocarbons (CFCs). While production of CFCs has been banned globally since 2010, HCFC production and usage is still being phased out.

Lead author Dr. Luke Western, Marie Curie Research Fellow at the University's School of Chemistry, said, "The results are very encouraging. They underscore the great importance of establishing and sticking to international protocols. Without the Montreal Protocol, this success would not have been possible, so it's a resounding endorsement of multilateral commitments to combat stratospheric ozone depletion, with additional benefits in tackling human-induced climate change."

The international study shows the total amount of ozone depleting chlorine contained in all HCFCs peaked in 2021. Because these compounds are also potent greenhouse gases, their contribution to climate change also peaked in that year. This maximum occurred five years before the most recent predictions. Although the drop between 2021 and 2023 was less than 1%, it still shows HCFC emissions are heading in the right direction.

Dr. Western said, "Their production is currently being phased out globally, with a completion date slated for 2040. In turn, these HCFCs are being replaced by non-ozone depleting hydrofluorocarbons (HFCs) and other compounds. By enforcing strict controls and promoting the adoption of ozone-friendly alternatives, the protocol has successfully curbed the release and levels of HCFCs into the atmosphere."

The results rely on high-precision measurements at globally distributed atmospheric observatories, using data from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Atmospheric and Oceanic Administration (NOAA).

"We use highly sensitive measurement techniques and thorough protocols to ensure the reliability of these observations," said co-author Dr. Martin Vollmer, an atmospheric scientist at the Swiss Federal Laboratories for Materials Science and Technology (EMPA).

Co-author Dr. Isaac Vimont, a research scientist at the NOAA in the United States, added, "This study highlights the critical need to be vigilant and proactive in our environmental monitoring , ensuring other controlled ozone depleting and greenhouse gases follow a similar trend which will help to protect the planet for future generations."

Journal information: Nature Climate Change

Provided by University of Bristol

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• Published: 04 June 2024

Global groundwater warming due to climate change

• Susanne A. Benz   ORCID: orcid.org/0000-0002-6092-5713 1 , 2 ,
• Dylan J. Irvine   ORCID: orcid.org/0000-0002-3543-6221 3 ,
• Gabriel C. Rau 4 ,
• Peter Bayer   ORCID: orcid.org/0000-0003-4884-5873 5 ,
• Kathrin Menberg 6 ,
• Philipp Blum 6 ,
• Rob C. Jamieson 1 ,
• Christian Griebler 7 &
• Barret L. Kurylyk   ORCID: orcid.org/0000-0002-8244-3838 1  

Nature Geoscience volume  17 ,  pages 545–551 ( 2024 ) Cite this article

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Aquifers contain the largest store of unfrozen freshwater, making groundwater critical for life on Earth. Surprisingly little is known about how groundwater responds to surface warming across spatial and temporal scales. Focusing on diffusive heat transport, we simulate current and projected groundwater temperatures at the global scale. We show that groundwater at the depth of the water table (excluding permafrost regions) is conservatively projected to warm on average by 2.1 °C between 2000 and 2100 under a medium emissions pathway. However, regional shallow groundwater warming patterns vary substantially due to spatial variability in climate change and water table depth. The lowest rates are projected in mountain regions such as the Andes or the Rocky Mountains. We illustrate that increasing groundwater temperatures influences stream thermal regimes, groundwater-dependent ecosystems, aquatic biogeochemical processes, groundwater quality and the geothermal potential. Results indicate that by 2100 following a medium emissions pathway, between 77 million and 188 million people are projected to live in areas where groundwater exceeds the highest threshold for drinking water temperatures set by any country.

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Earth’s climatic system warms holistically in response to the radiative imbalance from increased concentrations of greenhouse gases 1 . While the ocean absorbs most of this additional heat 2 , the terrestrial subsurface and groundwater also function as a heat sink. With a stable climate, seasonal temperature variation penetrates to a depth of 10–20 m, below which temperatures generally increase with depth in accordance with the geothermal gradient 3 . However, present-day borehole temperature–depth profiles frequently show an inversion (that is, temperature decreasing with depth) for up to 100 m due to recent, decadal surface warming 4 . Deviations from steady-state subsurface temperatures in deep boreholes (for example, >300 m) have been used to evaluate terrestrial heat storage and to estimate past, pre-observational surface temperature changes at a global scale 5 . Previous multi-continental synthesis studies on subsurface warming provide critical information on climate dynamics, but impacts on groundwater resources and associated implications are commonly ignored.

With the advent of the Gravity Recovery and Climate Experiment (GRACE) satellites, global datasets and global hydrological models, there is an emerging body of global-scale groundwater research 6 , 7 , 8 , 9 . However, global-scale groundwater studies so far have focused on resource quantity (for example, levels, recharge rates and gravity signals), whereas global-scale research into groundwater quality, including temperature, is rare. Furthermore, prominent syntheses of the relationship between anthropogenic climate change and groundwater (for example, refs. 10 , 11 ) concentrate on quantity leaving quality aspects unexplored 12 . Water temperature, sometimes known as the ‘master environmental variable’ (ref. 13 ), is an understudied groundwater quality parameter in the context of climate change.

Whereas global studies of river and lake warming have been conducted 14 , 15 , there are no global assessments of climate change impacts on groundwater temperatures (GWTs). This is despite the high importance of groundwater, which represents the largest global reservoir of unfrozen freshwater 16 , providing at least part of the water supply for half the world 17 and close to half of the global irrigation demand 18 . It also sustains terrestrial and aquatic ecosystems 19 , particularly in the face of climate change 10 . Given the role of temperature as an overarching water quality variable and observational evidence of groundwater warming in different countries in response to recent climate change 4 , 20 , 21 , the potential impact of climate warming on groundwater temperatures at a global scale remains a critical knowledge gap.

Groundwater temperature influences a suite of biogeochemical processes that alter groundwater quality 22 . For example, an increase in temperatures reduces gas solubility and raises metabolism of organisms, with an increased rate of oxygen consumption and a shift in redox conditions 23 . Because many aquifers already possess low oxygen concentrations, a small change in temperature could trigger a shift from an oxic to a hypoxic or even an anoxic regime 24 , 25 . This switch can in turn facilitate the mobilization of redox-sensitive constituents such as arsenic, manganese and phosphorus 26 , 27 . Increases in soluble phosphorus in groundwater discharging to surface water can trigger harmful algal blooms 28 , and elevated arsenic and manganese contents in potable water supplies pose direct risks to human health 29 . Groundwater warming will also cause a shift in groundwater community composition with a challenge to biodiversity and the risk of an impaired cycling of carbon and nutrients 24 , 25 . Shallow soil and groundwater warming may also cause temperatures in water distribution networks to cross critical thresholds, with potential health implications such as the growth of pathogens such as Legionella spp. 30 .

Diffusive discharge of thermally stable groundwater to surface water bodies modulates their temporal thermal regimes 30 . Also, focused groundwater inflows can create cold-water plumes that provide thermal refuge for stressed aquatic species 31 , including many prize cold-water fish. Accordingly, groundwater warming will increase ambient water temperatures in surface water bodies and the temperatures of groundwater-sourced thermal refuges. Spring ecosystems will also be affected. For example, crenobionts (true spring water species) have a very narrow temperature optimum and tolerance; hence, warming groundwater near the mouths of springs will lead to changes in their reproduction cycles, food web interactions and finally a loss of sensitive species 32 .

Groundwater warming can also have positive effects as the accumulated thermal energy can be recycled through shallow, low-carbon geothermal energy systems 33 . Whereas studies typically focus on recycling the waste heat from anthropogenic sources, particularly from subsurface urban heat islands 34 , the subsurface heat accumulating due to climate change also has the potential to sustainably satisfy local heating demands 35 . However, increased warming will make cooling systems less efficient 36 .

Here we develop and apply a global-scale heat-transport model (thermal diffusion) to quantify groundwater temperatures in space and time and their response to recent and projected climate change (Fig. 1a,b ). Our objective is to reveal the potential magnitude and long-term implications of ongoing shallow groundwater warming and to identify ‘hotspots’ of concern. The model utilizes standard climate projections to drive global groundwater warming down to 100 m below ground surface but with a focus on temperatures at the depth of the water table. We discuss (1) where aquifer warming will influence the viability of shallow geothermal heat recycling in the shallow subsurface (Fig. 1c ), (2) given how it impacts microbial activity and groundwater chemistry, where groundwater temperature may cross key thresholds set by drinking water standards (Fig. 1d ) and (3) where discharge of warmed groundwater will have the most pronounced impact on river temperatures and aquatic ecosystems (Fig. 1e ). Our model is global, and its resolution limits detailed capture of small-scale processes, producing conservative results based on tested hydraulic and thermal assumptions, including realistic advection from basin-scale recharge. More localized processes may lead to higher groundwater temperatures in areas with increased downward flow (for example, river-based recharge) or elevated surface temperatures (for example, urban heat islands) (Supplementary Note 1 provides details).

a – e , Increases in surface air and ground surface temperatures ( a ) drive increases in groundwater temperatures ( b ) that, in turn, impact the geothermal potential for shallow geothermal energy systems ( c ), groundwater chemistry and microbiology, which in turn impacts water quality ( d ) and groundwater-dependent ecosystems ( e ). Figure created with images from the UMCES IAN Media Library under a Creative Commons license CC BY-SA 4.0 .

Groundwater temperatures

We use gridded data to calculate transient subsurface temperature–depth profiles across the globe ( Methods ). Besides past and current temperatures, we present potential (modest mitigation) and worst-case (no mitigation) projections to 2100 based on the Shared Socioeconomic Pathway (SSP) 2–4.5 or SSP 5–8.5 climate scenarios of phase 6 the Coupled Model Intercomparison Project (CMIP6) (ref. 37 ). Results can be accessed and visually explored using an interactive Google Earth Engine app available at https://susanneabenz.users.earthengine.app/view/subsurface-temperature-profiles . Figure 2a–c displays maps of mean GWT at the depth of the water table and at 5 and 30 m below ground surface for 2020.

a – c , Map of modelled mean annual temperatures at the depth of the water table ( a ), at 5 m below ground surface ( b ) and at 30 m below ground surface ( c ) in 2020. d , Comparison of modelled and observed groundwater temperatures. Blue markers are (multi-) annual mean temperatures observed between 2000 and 2015 at an unspecified depth against modelled temperatures of the same time period at 30 m depth. Grey markers are temperatures of a single point in time versus modelled temperatures of the same time and depth. A histogram of the errors (observed minus modelled temperatures) is shown in the upper left corner. e , Modelled temperature–depth profiles showing mean annual temperatures and the seasonal envelope for the locations displayed in a . Please note that we use bulk thermal properties, and the water table depth is thus not an input parameter into our model.

Comparison with measured data demonstrates a good accuracy of the model given the global scale with a root mean square error of 1.4 °C and a coefficient of determination of 0.75 (Fig. 2d ). An in-depth discussion on model reliability, uncertainty and limitations is given in Supplementary Note 2 .

The median GWT at the water table in 2020 was 21.0 °C (5.6 °C, 29.3 °C; 10th, 90th percentile; Fig. 2a ). In comparison, using the same ECMWF re-analysis (ERA-5) data product, air temperatures in 2020 were lower at 17.6 °C (1.4 °C, 27.0 °C). This thermal offset is attributable to various processes and conditions including snow pack insulation in colder climates 38 and increased temperatures with depth following the geothermal gradient.

Simulated temperature–depth profiles are displayed at six example locations in Fig. 2e , including their seasonal envelope. Supplementary Note 3 provides a discussion of seasonality. Whereas all locations show an inversion of the temperature–depth profile, the depth at which this thermal gradient ‘inflection point’ (ref. 4 ) is reached varies greatly based on the rate and duration of recent climate change. At the example location in Mexico, temperatures begin to increase with depth (as expected based on the local geothermal gradient) from approximately 10 m downwards, whereas at the example location in Brazil, the inflection point reaches a depth of 45 m (Fig. 2c ). Globally, it has reached 15 (<1, 40) m (Extended Data Fig. 1a ). Heat advection from vertical groundwater flow may also influence the depth of the inflection point 4 , but only heat diffusion is considered in our model as this is the dominant heat-transport mechanism at the modelled spatial scale ( Methods ).

To better assess the impact of recent climate change on groundwater temperatures at the water table depth, we compare annual mean GWTs from 2000 and 2020. Over this 20-year period, GWTs increased on average by 0.3 (0.0, 0.8) °C (Fig. 3a ). We do not find any distinct large-scale patterns. However, some of the highest temperature increases occur in parts of Russia (for example, > + 1. 5 ∘ C north of Novosibirsk), while parts of Canada experienced cooling (for example, < −0. 5 °C in Saskatoon) between the two years. Both regions have shallow water tables, with GWTs tightly coupled to seasonal surface temperature variations and short-term intra-annual changes, rather than just the long-term surface temperature signals. As such, one hot summer can drastically alter the modelled GWT difference between 2000 and 2020. The influence of weather conditions for a given year is also notable in the depth profiles for six selected locations (Fig. 3d ). Noticeable variations occur in the upper 5 m of mean temperature range profiles with temperature changes of 1.1 °C at the location in Australia, compared with 0.5 °C at the location in Nigeria. These effects of intra-annual and short-term interannual variations in weather are attenuated at greater depths (for example, 30 m). Long-term (climate change) effects penetrate deeper, although groundwater warming may be less pronounced with depth due to the time lag between surface and subsurface temperature signals (Fig. 3c ).

a – d , Recent (2000 to 2020) changes. e – h , Projected (2000–2100) changes. a , e , Map of the change in annual mean temperature at the depth of the water table. The line in the legend indicates 0 °C. b , c , f , g , Temperature change 5 m below the land surface ( b , f ) and 30 m below the land surface ( c , g ). d , h , Change in temperatures between 2000 and 2020 ( d ) and difference between 2000 and 2100 ( h ) as depth profiles for selected locations (symbols in a and e ). Lines in h indicate median projections, whereas 25th to 75th percentiles (pct.) are presented as shading.

Over the entire century (between 2000 and 2100), groundwater warming is also projected to increase; globally averaged GWTs at the water table (at its current level) increase by 2.1 (0.8, 3.0) °C following SSP 2–4.5 median projections (Fig. 3e–g ; Extended Data Fig. 2 for 25th (1.7 (0.6, 2.5) °C) and 75th percentile (2.6 (1.0, 3.6) °C) projections) and by 3.5 (1.0, 5.5) °C following SSP 5–8.5 median projections (Extended Data Figs. 3a–d and 4 ; 25th percentile projections 3.0 (0.8, 5.8) °C; 25th percentile projections 4.6 (1.3, 7.1) °C).

We observe a clear signal of climate change by studying the depth down to which the temperature profile is reversed and temperatures are decreasing outside of seasonal effects. In 2100 the geothermal gradient inflection point is projected to reach 45 (9, 90) m on average following SSP 2–4.5 median projections (40 (6, 90) m for 25th percentile and 45 (15, 80) m for 75th percentile projections) or 60 (40, 100) m following SSP 5–8.5 median projections (60 (35, >100) m for 25th percentile and 60 (45, >100) m for 75th percentile projections; Extended Data Figs. 1b,c and 5 ).

Accumulated energy

The overall increase in GWT can be quantified as accumulated energy ( Methods ). By 2020, a net energy amount of 14 × 10 21  J has already been absorbed by the terrestrial subsurface (Fig. 4a ; 119 (45, 202) MJ m −2 ) since the beginning of the industrial revolution. In comparison, 436 × 10 21  J or about 25 times more has been absorbed by the oceans over a similar time period 39 . A review of Earth’s energy imbalance identifies a total heat gain of 358 × 10 21  J for the time period 1971–2018 only, attributing about 6% of that to land areas including permafrost regions (21 × 10 21  J, that is, a similar magnitude as our estimate) 40 . In a similar range is the 23.8 × 10 21  J that was stored in the continental landmass since 1960 following a recent study; 90% is from heat storage 41 .

a – c , Current status in 2020. d – f , Projected status in 2100 under SSP 2–4.5. a , d , Accumulated heat from the surface to 100 m depth. The line in the legend indicates 0 MJ m −2 . b , e , Map showing locations where maximum monthly GWTs at the thermal gradient inflection point (coldest depth) are above guidelines for drinking water temperatures (DWTs) 43 . c , f , GWT changes between 2000 and 2020 ( c ) and between 2000 and 2100 ( f ) at stream sites with a groundwater signature 49 . The line in the legend indicates 0 °C.

We project that by 2100 accumulated subsurface energy will be 41 × 10 21  J following SSP 2–4.5 median projections (343 (251, 463) MJ m −2 ; Fig. 4d ), 30 × 10 21  J following 25th percentile projections (255 (162, 361) MJ m −2 ) and 50 × 10 21  J following 75th percentile projections (424 (324, 560) MJ m −2 ; Extended Data Fig. 6 ). Under SSP 5–8.5 we get 62 × 10 21  J for the median projections (518 (384, 689) MJ m −2 ; Extended Data Fig. 3e ), 49 × 10 21  J for the 25th percentile projections (412 (285, 564) MJ m −2 ) and 77 × 10 21  J for the 75th percentile projections (644 (493, 844) MJ m −2 ; Extended Data Fig. 7 ). This accumulated heat can be extracted from the subsurface through wells in productive aquifers, but in lower-permeability zones and the unsaturated zone, less-efficient borehole heat exchangers would be necessary 33 . Hence, we assessed the energy accumulated in the saturated zone only (below the current water table) in Extended Data Fig. 8 —on average, there is 68 (13, 133) MJ m −2 of heat in the global subsurface saturated zone in 2020.

By comparing the accumulated aquifer thermal energy in the United States (about 45 MJ m −2 ) with local residential heating demands (about 35,000 MJ per household in 2015 following the US Energy Information Administration 2015 Energy Consumption Survey), we find that, if recycled, the energy accumulated below an average home (250 m 2 for the floor area in new single-family houses following the 2015 ‘Characteristics of new housing’ report, US Department of Commerce) in 2020 would fulfil about four months of heating demands. However, by 2100, global heat storage in the saturated zone is projected to increase to 233 (75, 363) MJ m −2 following SSP 2–4.5 and 352 (105, 536) MJ m −2 following SSP 5–8.5 median projections (Extended Data Figs. 8 and 9 for 25th and 75th percentile projections). With heating demands projected to decline due to higher temperatures and improved building insulation, recycling this subsurface heat will therefore become more feasible and is a carbon-reduced heat source that will benefit from climate change 35 . Conversely, cooling systems that rely on geothermal sources will be less efficient.

Implications for drinking water quality

Whereas groundwater warming offers benefits for geothermal heating systems, the accumulated heat also threatens water quality. In many developing countries or in poor and rural areas within developed countries, groundwater may be consumed directly without treatment or storage. It may also indirectly impact temperatures of drinking water within pipes 42 . In these regions in particular, the changes in water chemistry or microbiology that are associated with groundwater warming have to be carefully considered.

According to the World Health Organization, only 18 of 125 countries have temperature guidelines for drinking water 43 . These temperature guidelines, which are often aesthetic guidelines, range from 15 °C to 34 °C, with a median of 25 °C. Figure 4b shows where annual maximum groundwater temperatures at the geothermal gradient inflection point, that is, the most conservative depth as it is the coldest point in the temperature–depth profile, are above these thresholds in 2020. At this time, more than 29 million people live in areas where our modelled maximum GWT exceeded 34 °C. If water is extracted at the depth of the water table, this increases to close to 31 million (Extended Data Fig. 10 ). Following SSP 2–4.5 median projections by 2100, these numbers will increase to 77 million to 188 million depending on the depth of extraction (72 to 101 for 25th percentile projection; 86 to 395 for 75th percentile projections; Fig. 4d and Extended Data Figs. 5 and 9 ). Following SSP 5–8.5 median projections, 59 million to 588 million people will live in areas where maximum GWTs exceed the highest thresholds for drinking water temperatures (54 to 314 for 25th percentile projection; 66 to 1,078 for 75th percentile projections; Extended Data Figs. 3f , 6 and 9 ). Due to the different population distributions, SSP 5–8.5 projects fewer people at risk than SSP 2–4.5 for the lower estimates.

Implications for groundwater-dependent ecosystems

The ecosystems most dependent on groundwater are those in the aquifers themselves. A temperature increase may threaten groundwater biodiversity and ecosystem services 44 , 45 . Also, the increased metabolic rates of microbes caused by warming will accelerate the cycling of organic and inorganic matter, additionally fuelled by the increasing importance of dissolved organic carbon to the subsurface 46 . Combined with decreasing groundwater recharge as projected for many North African, southern European and Latin American countries 47 , this may transform oxic subsurface environments into anoxic 24 .

Groundwater warming also threatens many riverine groundwater-dependent ecosystems and the industries (for example, fisheries) that they support 48 . To capitalize on past continental-scale research related to groundwater, river temperature and ecosystems, we compare our modelled spatial patterns of groundwater warming in the conterminous United States to a recent distributed analysis of 1,729 stream sites 49 . The amplitude and phase of seasonal temperature signals in these surface water bodies were used to reveal the thermal influence and source depth of groundwater discharge to these streams, with about 40% classified as groundwater dominated. Our results show that GWT at the water table for the groundwater-dominated stream sites increased by 0.1 (0.0, 0.4) °C between 2000 and 2020 and 1.3 (0.3, 2.6) °C and 1.9 (0.4, 4.5) °C between 2000 and 2100 following SSP 2–4.5 and SSP 5–8.5 median projections, respectively (Fig. 4c,f and Extended Data Fig. 3g ). Twenty-fifth percentile projections reveal 0.7 (−0.1, 1.5) °C and 1.0 (0.0, 2.9) °C and 75th percentile projections 2.0 (0.5, 4.0) °C and 2.9 (0.6, 6.7) °C between 2000 and 2100 following SSP 2–4.5 and SSP 5–8.5, respectively (Extended Data Figs. 6 and 7 ).

The warming groundwater will inevitably raise the ambient temperature of surface water systems thermally influenced by groundwater discharge. Furthermore, such groundwater warming will even more strongly impact the thermal regimes of groundwater-fed thermal refuges (for example, at the outlets of springs or groundwater-dominated tributaries flowing into rivers) and cause them to more regularly cross critical temperature thresholds for resident species seeking relief from thermal stress. Given the connection between aquifer thermal regimes and river sediment temperatures 50 , groundwater warming also threatens the thermal suitability of benthic ecosystems and spawning areas for fish 51 , posing a major risk to fisheries and other dependent industries.

Summary and model application

In summary, global climate change is leading to increased atmospheric and surface water temperatures, both of which have already been assessed across spatial scales ranging from local to global. Here we contribute to the global analyses of environmental temperature change and of groundwater resources through the presentation of projected groundwater temperature change to 2100 at a global scale. Our analyses are based on reasonable hydraulic and thermal assumptions providing conservative estimates and allow for both the hindcasting and forecasting of groundwater temperatures. Future groundwater temperature forecasts are based on both SSP 2–4.5 and 5–8.5 climate scenarios. We provide global temperature maps at the depth of the water table, 5 and 30 m below land surface, and these highlight that places with shallow water tables and/or high rates of atmospheric warming will experience the highest groundwater warming rates globally. Importantly, given the vertical dimension of the subsurface, groundwater warming is inherently a three-dimensional (3D) phenomenon with increased lagging of warming with depth, making aquifer warming dynamics distinct from the warming of shallow or well-mixed surface water bodies.

To facilitate more detailed future analyses, the temperature maps are included in a Google Earth Engine app at https://susanneabenz.users.earthengine.app/view/subsurface-temperature-profiles . The gridded GWT output could be integrated with global river temperature models 52 to more holistically understand future warming in aquifers and connected rivers. Whereas the warming of Earth’s groundwater poses some opportunities for geothermal energy production, it increasingly threatens ecosystems and the industries depending on them, and it will degrade drinking water quality, primarily in less-developed regions.

Diffusive heat transport

We hindcast monthly subsurface temperatures (and therefore also groundwater temperatures (GWTs) based on the assumption of local equilibrium) from the surface to a depth of 100 m for the years 2000 to 2020. We also force our model with future projections following SSP 2–4.5 and SSP 5–8.5 up to the year 2100. Subsurface temperatures in the shallow crust are generally controlled by one-dimensional (1D) (vertical) diffusive heat transport. Heat advection due to water flow plays a lesser and often inconsequential role in controlling subsurface temperatures 54 , 55 , 56 , particularly at larger spatial scales that average out focused groundwater flows in faults and fractures and groundwater exchange with surface water bodies. We adopt our 1D diffusion-dominated approach rather than a 3D numerical model of coupled groundwater flow and heat transfer as there are presently neither the parameterization data nor the computing power to enable such a coupled, 3D water and thermal transport model at a global scale. Also, whereas the influence of heat advection on steady-state or transient, subsurface temperature–depth profiles can be detected with precise temperature loggers and yields valuable insight into vertical groundwater fluxes when heat is used as a groundwater tracer 57 , the rate of shallow groundwater warming is often not thought to be strongly influenced by typical basin-average, vertical groundwater flux rates. Accordingly, heat advection has been ignored in some past local-scale groundwater warming studies (for example, ref. 58 ). However, to further investigate the thermal effects of multi-dimensional flow, we run a suite of scenarios and find that advection only exerts a minor influence on groundwater warming rates for typical groundwater flow conditions (Supplementary Note 1 ), enabling us to employ our approach.

Appropriate initial conditions can be far more important for reliable simulation of temperature–depth profiles than the inclusion of heat advection 59 . To ensure our initial conditions are not influenced by any preceding climate change, we initiate our model in 1880 when the industrial revolution had not yet increased atmospheric greenhouse gasses and the climate was relatively stable. As default initial setting, we define a temperature–depth profile that increases linearly with depth z from the surface T S in accordance with the geothermal gradient a : T ( z ) =  T S  +  a z (ref. 55 ). In permafrost regions, warming above critical thresholds requires latent heat to thaw ground in addition to the sensible heat to raise the temperature. As we do not include latent heat effects, model results are not presented for permafrost regions 60 .

We use the following analytical solution to the transient 1D heat diffusion equation for a semi-infinite homogeneous medium subject to a series of n step changes in surface temperature 55 :

where j is a step change counter (counting by month), t is time, T S ( t ) is the time series of the ground surface temperature, D is the thermal diffusivity and erfc is the complementary error function. This equation is often used in an inverse manner to reconstruct pre-observational ground surface temperature history from observed, deep temperature–depth profiles, demonstrating its utility for investigating the response of subsurface thermal regimes to surface warming.

We run our model in Google Earth Engine (GEE) 61 , and the results are presented in the form of a Google Earth Engine app openly accessible at https://susanneabenz.users.earthengine.app/view/subsurface-temperature-profiles . The application presents zoomable maps of annual mean, maximum and minimum GWT at different depths and seasonal variability (maximum minus minimum) for selected years and climate scenarios. All datasets were created at a native 5 km resolution at Earth’s surface. However, Google Earth Engine automatically rescales images shown on the map based on the zoom level of the user. Charts that represent temperatures at a given location at a 5 km scale are created by clicking on the map and can be exported in CSV, SVQ or PNG file formats. For all analyses showing annual mean data at the water table depth, we first calculate monthly temperatures at the associated monthly groundwater level before averaging the results.

Ground surface temperatures

We use two distinct ground surface temperature time series: (1) one for the analysis of current (2020) temperatures based primarily on the ERA-5 data 62 and (2) one for the analysis of projected changes based on CMIP6 data 37 . On the basis of available computational power and data, we are not able to utilize monthly temperatures for the entire time period between the years 1880 and 2100. Instead, we present monthly temperatures from 1981 onwards and annual mean temperatures for 1880. The threshold 1981 is selected as ERA-5 data were available in Google Earth Engine from this point on when developing the model.

As these data are input into the analytical step function model (equation ( 1 )), we supplement them with mean temperatures of the early 1980s (that is, three-year mean 1981 to 1984) to reduce artefacts of the sudden onset of seasonal signals in our data. An example of the ground surface temperature time series is shown in Supplementary Fig. 11 .

For the analysis of current GWT, we use monthly mean soil temperature at 0–7 cm depth for the years 1981 to 2022 based on the ERA-5-Land monthly average reanalysis product 62 to form the ground surface temperature boundary condition for equation ( 1 ). These data have a native resolution of 9 km at the surface and are available through the GEE data catalogue. We also used annual ground temperature anomalies of 1880 of the top layer following the Goddard Institute for Space Studies (GISS) atmospheric model E 63 . This dataset gives the temperature difference between 1880 and 1980 in a horizontal resolution of 4° × 5° (approximately 444 km × 555 km at the equator) and can be extracted from https://data.giss.nasa.gov/modelE/transient/Rc_ij.1.11.html . To obtain absolute temperatures of 1880, we subtract the anomalies from three-year mean temperatures (1981 to 1984) of the ERA-5 data.

Future projections of ground surface temperatures are based on monthly soil temperatures closest to the surface for scenarios SSP 2–4.5 and SSP 5–8.5 from the CMIP6 programme available from 2015 to 2100. Model selection and methodology follow previous work 64 , but were updated to CMIP6 based on availability. In total we use nine models: BCC-CSM2-MR, CanESM5, GFDL-ESM4, GISS-E2-1-G, HadGEM3-GC31-LL, IPSL-CM6A-LR, MIROC6, MPI-ESM1-2-LR, NorESM2-MM. Where available, we used data from the variant label r1i1p1f1; however, for GISS-E2-1-G and HadGEM3-GC31-LL, these were not available, and we had to use r1i1p1f2 or r1i1p1f3 instead. Furthermore NorESM2-MM was missing data for January 2015; thus, we replaced them with data from December 2014 from the historic scenario. Data were collected from the World Climate Research Programme at https://esgf-node.llnl.gov/search/cmip6/ . In addition, monthly data of the historic scenario were prepared for January 1981 to December 2014 and the annual mean data for 1880. To account for the difference between the CMIP6 models and ERA-5 reanalysis, we adjust the CMIP6 outputs based on mean temperatures \(\overline{T}\) from ERA-5 between 1981 and 2014 (that is, the overlap between ERA-5 and the CMIP6 historic scenario) for each of the CMIP6 models separately as follows:

Temperatures are determined for each model before being presented as the median and the 25th and 75th percentiles.

Thermal diffusivity

For our analysis we use the ground thermal diffusivity D :

where λ (W m −1  °C −1 ) is the bulk thermal conductivity and C V (J m −3  °C −1 ) is the bulk volumetric heat capacity. Ground thermal conductivity and volumetric heat capacity for various water saturation values are derived following previous examples 35 , 65 . This method links λ and C V values for different soil and/or rock types following the VDI 4640 guidelines 66 to a global map of soil and/or rock type. This map is based on grain size information of the unconsolidated sediment map database (GUM) 67 . Where there is no available sediment class, we link to soil type in GUM. When this is also not available, we rely on the global lithological map database (GLiM) 68 . All required datasets were uploaded to Google Earth Engine in their native resolution. For assigned values, refer to Supplementary Table 1 .

We acknowledge that the distribution of subsurface thermal properties is heterogeneous. However, specific heat capacity and thermal conductivity for rocks are both well constrained to within less than half an order of magnitude 69 , 70 compared with the many orders of magnitude for hydraulic conductivity 71 . We also note that water saturation can change the individual thermal properties and have accordingly run our model for six example locations with three different diffusivity values: (1) a dry soil, (2) a moist soil (default) and (3) a water saturated soil (Supplementary Fig. 12 ). The influence of water saturation on thermal diffusivity can be complex as both the heat capacity and thermal conductivity increase with water content (equation ( 3 )). Overall, for locations with unconsolidated material in the shallow subsurface, groundwater warming rates increase with water saturation. However, the effect is nonlinear and the overall impact of water saturation on the thermal diffusivity is negligible for relative saturation values between 0.5 and 1 (ref. 72 ). A map of the diffusivity utilized here is given in Supplementary Fig. 13a .

Geothermal gradient

When advection is absent, the geothermal gradient a (°C m −1 ; equation ( 1 )) is the rate of temperature change with depth due to the geothermal heat flow Q (W m −2 ) and thermal conductivity λ (W m −1  °C −1 ):

with global values for λ derived as described earlier, and the mean heat flow Q available as a global 2° equal area grid (about 222 km at the equator) 73 . Due to their resolution, these data do not incorporate fractures and major faults, and we thus are not able to estimate groundwater temperatures at these locations properly. The grid was uploaded to GEE in its native resolution for analysis (Supplementary Fig. 13b ).

Water table depth

Much of our analysis and interpretation focuses on the future projection of temperatures at the water table depth. We therefore use the results of a previously published global groundwater model 74 , 75 with a 30 sec grid (about 1 km at the equator) to obtain the mean water table depth for 2004 to 2014. These data are available as monthly averages that we uploaded to GEE in their native resolution. In temperate climates, the model underestimates the observed water table depth by 1.5 m, and we therefore set the minimum water table depth to 1.5 m as was done in a previous study 35 . Still, whereas the global-scale hydro(geo)logical model of Fan et al. 74 , 75 can reveal large-scale patterns, it is of limited use for small-scale analysis and must be used with caution. Hence we run additional information for best- and worst-case scenarios where we add or subtract 10 m to the depth of the water table (Supplementary Note 4 ).

To calculate mean annual GWTs at the water table, temperatures for each month were determined at the corresponding water table depth by setting z in equation ( 1 ) to this depth. Future changes of water table elevation are challenging to predict, and we therefore base our analysis on the assumption that future water table elevations are unchanging. If we assume that the water table will rise, then warming would be more extreme; should the water table lower, warming as projected here is overestimated. A more detailed discussion, modelling water table changes of ± 10 m, can be found in Supplementary Note 4 . However, we note that a modelled temperature–depth profile (equation ( 1 )) is not impacted by the choice of the water table depth, and thus the results at 10 and 30 m are independent of the water table model.

Model evaluation

To assess the performance of our GWT calculations, we use two datasets of measured GWT or borehole temperatures. First, we compare our data to (multi-)annual mean shallow GWTs introduced in Benz et al. 35 . These data comprise more than 8,000 individual locations, primarily in Europe, where GWTs were measured at least twice between 2000 and 2015 at less than 60 m depth. Measurements are filtered based on their seasonal radius, a measure describing if a well was observed uniformly over the seasons and mean temperatures are therefore free of seasonal bias 76 . Second, we compare our data to temperature–depth profiles from the Borehole Temperatures and Climate Reconstruction Database at https://geothermal.earth.lsa.umich.edu/core.html . For these data, an exact date and depth of measurement are known. We filter the database based on time of measurement and depth of the first measurement, using only data taken after the year 2000 and starting at less than 30 m depth, resulting in 72 borehole measurements. To evaluate the model, we compare it to the observed groundwater temperatures described above. We compare the shallow (multi-)annual mean temperatures to mean temperatures at 30 m depth (the middle between 0 m and 60 m, the maximum depth of the observations) between 2000 and 2015. For the dataset of one-time borehole temperature–depth profiles, we compare the shallowest data points to temperatures from our model at the same depth (rounded to the nearest metre), month and year.

Example locations

We use six locations distributed over all latitudes as examples in many of our figures, with locations in Australia (longitude 149.12°, latitude −35.28°), Brazil (−47.92°, −15.77°), China (116.39°, 39.90°), Mexico (−99.12°, 19.46°), Norway (10.74°, 59.91°) and Nigeria (7.49°, 9.05°). For convenience, each point is at the location of the capital city. However, as our model is not able to adequately describe the impact of urban heat on measured groundwater temperatures, groundwater at these locations is expected to be warmer, potentially by several degrees. Our focus is on the rate of warming in response to climate change.

Depth of the geothermal gradient ‘inflection point’

To find the depth d i down to which annual mean temperature–depth profiles T ( z ) are inverted (that is, decrease with depth as opposed to increase following the geothermal gradient 4 ), we find the maximum depth where T ( d i ) >  T ( d i +1 ). Given our computational resources, we test this at a resolution of 1-m steps for the first 10 m, then in 5-m steps down to 50 m depth and lastly in 10-m steps down to the maximal depth of 100 m.

To quantify shallow subsurface accumulated energy I (J m −2 ), we compare mean annual temperature–depth profiles down to 100 m depth to the initial conditions T ( z ) =  T S ( t  = 1,880) +  a z by solving the following integral in 1-m steps:

This analysis utilizes annual mean subsurface temperatures \(\overline{T}(z)\) for 2020 or 2100 for the current and projected analyses, respectively. The volumetric heat capacity C V ( z ) of the unsaturated zone (for z above the water table) and the saturated zone (for z below the water table) uses discrete values given in Supplementary Table 1 .

Drinking water temperature thresholds

To assess the impact of groundwater warming on drinking water resources, we compare annual maximum groundwater temperatures to thresholds for drinking water temperatures summarized by the World Health Organization 43 . We do so for temperatures at the depth of the thermal gradient inflection point, the coldest point in the temperature profile and thus a best-case scenario, and for the depth of the water table to capture the 6% to 20% of wells that are no more than 5 m deeper than the water table 77 . To quantify populations at risk of exceeding the threshold, we compare the resulting maps with population counts. For temperatures in 2022, we use the 2015 United Nations-adjusted population density from the Population of World Version 4.11 Model 78 . For future scenarios, we rely on the global population projection grids for 2100 from the SSPs 79 , 80 . These data are available through the socioeconomic data and applications centre.

Impact on surface water bodies

Temperatures in surface water bodies are strongly influenced by atmospheric heat fluxes, but groundwater discharge and other processes can decouple temperatures in the atmosphere and water column. In the United States, 1,729 stream sites have been analysed by Hare et al. 49 to determine the dominance of groundwater discharge and to ascertain the relative depth (shallow or deep) of the associated aquifers. We use these sites to extract changes in mean annual groundwater temperature at the depth of the water table from our results to assess the impact of groundwater warming on these surface water bodies.

Data availability

Raster files (5 km resolution, in the GeoTIFF format) and tables (.CSV) used to create all figures of this study are made available at the Scholars Portal Dataverse at https://doi.org/10.5683/SP3/GE4VEQ (ref. 81 ). An online tool to facilitate exploration of our groundwater temperature model is available at https://susanneabenz.users.earthengine.app/view/subsurface-temperature-profiles .

Code availability

All codes used are also available at the Scholars Portal Dataverse under https://doi.org/10.5683/SP3/GE4VEQ (ref. 81 ). This includes codes written with Jupyter Notebook (Python) and Google Earth Engine (Javascript and GoogleColab/Python) and a detailed description of the process (readme.txt).

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Acknowledgements

S.A.B. was supported through a Banting postdoctoral fellowship, administered by the government of Canada, and since October 2022 as a Freigeist fellow of the Volkswagen Foundation. B.L.K. was supported through the Canada Research Chairs programme. K.M. was supported by the Margarete von Wrangell programme of the Ministry of Science, Research and the Arts Baden-Württemberg (MWK). We thank C. Tissen for sharing data she collected in her study on groundwater temperature anomalies in Europe 53 and the many other people and agencies collecting groundwater temperature data and making them available through (publicly accessible) databases. Without these data, successful validation of our method would not have been possible.

Open access funding provided by Karlsruher Institut für Technologie (KIT).

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Susanne A. Benz, Rob C. Jamieson & Barret L. Kurylyk

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Susanne A. Benz

Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia

Dylan J. Irvine

School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales, Australia

Gabriel C. Rau

Department of Applied Geology, Martin Luther University Halle-Wittenberg, Halle, Germany

Peter Bayer

Institute of Applied Geosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany

Kathrin Menberg & Philipp Blum

Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria

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S.A.B., B.L.K. and D.J.I. designed the study. S.A.B., B.L.K., D.J.I., G.C.R., P. Blum, K.M. and P. Bayer developed the methodology. S.A.B. prepared all data and code for analysis and designed figures. D.J.I. designed Fig. 1 . D.J.I. and G.C.R. designed, performed and led the discussion of the analysis in Supplementary Note 1 . S.A.B., B.L.K., D.J.I. and G.C.R. wrote the manuscript. All authors interpreted results and edited the manuscript together.

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Extended data

Extended data fig. 1 depth to the inflection point..

Shown is the depth down to which we can trace the impact of climate change in form of inverted temperature-depth profiles, that is temperature is decreasing with depth and not increasing with depth as expected based on the geothermal gradient. a and b , The depth to the geothermal inflection point in 2020 and 2100 following SSP 2-4.5. c , The depth to the geothermal inflection point in 2100 following SSP 5-8.5.

Extended Data Fig. 2 Change in groundwater temperatures following SSP 2-4.5, 25th and 75th percentile projections.

a – f , Map of the change in annual mean temperature between 2000 and 2100 following SSP 2-4.5 at the depth of the water table (under consideration of its seasonal variation). Temperatures in 2000 are based on the historic CMIP6 scenario. The line in the legend indicates 0 ∘ C. b and e , Annual mean groundwater temperature 5 m below the surface. c and f , Annual mean groundwater temperature 30 m below the surface. a – c , Annual mean groundwater temperature 25th percentile projected changes. d – f , Annual mean groundwater temperature 75th percentile projected changes.

Extended Data Fig. 3 Change in groundwater temperatures between 2000 and 2100 and implications following SSP 5-8.5.

a , Map of the change in annual mean temperature between 2000 and 2100 following SSP 5-8.5 (median projections) at the depth of the water table (under consideration of its seasonal variation). Temperatures in 2000 are based on the historic CMIP6 scenario. The line in the legend indicates 0 ∘ C. b , temperature change 5 m below the surface, and c , 30 m below the surface. d , Change in temperatures between 2000 and 2100 as depth profiles for selected locations. Lines indicate median projections whereas 25th to 75th percentile are presented as shading. e , Accumulated heat down to 100 m depth. The line in the legend indicates 0 MJ per m 2 . f , Map showing locations where maximum monthly GWTs at the thermal gradient inflection point (that is coldest depth) in 2100 are above guidelines for drinking water temperatures (DWTs). g , GWT changes between 2000 and 2100 at stream sites with a groundwater signature.

Extended Data Fig. 4 Change in groundwater temperatures following SSP5-8.5, 25th and 75th percentile projections.

a and d , Map of the change in annual mean temperature between 2000 and 2100 following SSP5-8.5 at the depth of the water table (under consideration of its seasonal variation). Temperatures in 2000 are based on the historic CMIP6 scenario. The line in the legend indicates 0 ∘ C. b and e , Annual mean groundwater temperature 5 m below the surface. c and f , Annual mean groundwater temperature 30 m below the surface. a to c , Annual mean groundwater temperature 25th percentile projected changes. d to f , Annual mean groundwater temperature 75th percentile projected changes.

Extended Data Fig. 5 Depth to the inflection point for 25th and 75th SSP projections.

The depth down to which we can trace the impact of climate change in form of inverted temperature-depth profiles, that is temperature is decreasing with depth and not increasing with depth as expected based on the geothermal gradient. a and b , The inflection point for SSP2-4.5 in 2100 based on 25th percentile or 75th percentile projections, respecively. c and d , The inflection point for SSP5-8.5 in 20100 based on 25th percentile or rather 75th percentile projections.

Extended Data Fig. 6 Implication of groundwater warming for SSP 2-4.5 25th and 75th percentile projections.

a and d , Accumulated heat down to 100 m depth for SSP 2-4.5 25th and 75th percentile projections, respectively. The line in the legend indicates 0 MJ per m 2 . b and e , Locations where maximum monthly GWTs at the thermal gradient inflection point (that is coldest depth) in 2100 are above guidelines for drinking water temperatures (DWTs) for SSP 2-4.5 25th and 75th percentile projections, respectively. c and f , GWT changes between 2000 and 2100 at stream sites with a groundwater signature for SSP 2-4.5 25th and 75th percentile projections, respectively.

Extended Data Fig. 7 Implication of groundwater warming for SSP 5-8.5 25th and 75th percentile projections.

a and d , Accumulated heat down to 100 m depth for SSP 5-8.5 25th and 75th percentile projections, respectively. The line in the legend indicates 0 MJ per m 2 . b and e , Locations where maximum monthly GWTs at the thermal gradient inflection point (that is coldest depth) in 2100 are above guidelines for drinking water temperatures (DWTs) for SSP 5-8.5 25th and 75th percentile projections, respectively. c and f , GWT changes between 2000 and 2100 at stream sites with a groundwater signature for SSP 5-8.5 25th and 75th percentile projections, respectively.

Extended Data Fig. 8 Accumulated heat in the saturated zone (that is, below the water table) down to 100 m depth.

a , Accumulated heat in the saturated zone in 2020. b and c , Accumulated heat in the saturated zone in 2100 following median projections of SSP2-4.5 and SSP5-8.5, respectively.

Extended Data Fig. 9 Accumulated heat in the saturated zone (defined as below the water table down to 100 m depth) and maximum temperatures (based on monthly GWTs) at the depth of the geothermal inflection point showing exceedence of guideline thresholds for drinking water temperatures (DWTs) for 25th and 75th percentile SSP projections.

a and b , Accumulated heat in the saturated zone for SSP 2-4.5 25th and 75th percentile projections, respectively. c and d , Locations where maximum temperatures exceed guideline thresholds for drinking water temperatures (DWTs) for SSP 2-4.5 25th and 75th percentile projections, respectively. e and f , Accumulated heat in the saturated zone for SSP 5-8.5 25th and 75th percentile projections, respectively. g and h , Locations where maximum temperatures exceed guideline thresholds for DWTs for SSP 5-8.5 25th and 75th percentile projections, respectively.

Extended Data Fig. 10 Locations where maximum monthly GWTs at the depth of the water table exceed guideline thresholds for drinking water temperatures (DWTs).

a , Maximum monthly GWTs at the depth of the water table in 2020. b and c , Maximum monthly GWTs at the depth of the water table in 2100 following median projections of SSP2-4.5 and SSP5-8.5, respectively.

Supplementary information

Supplementary information.

Supplementary Notes 1–4, Figs. 1–17 and Tables 1–5.

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Benz, S.A., Irvine, D.J., Rau, G.C. et al. Global groundwater warming due to climate change. Nat. Geosci. 17 , 545–551 (2024). https://doi.org/10.1038/s41561-024-01453-x

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Five things to know about… hurricane season.

(Credit: NASA)

Not many people know which way the wind blows better than Alexey Fedorov .

Fedorov, a professor of ocean and atmospheric sciences in Yale’s Faculty of Arts and Sciences, has made a life’s work of sorting through some of the dynamics of atmospheric moisture, rainfall, wind, temperature, and ocean circulation that combine to create dramatic climate and weather events.

He has conducted leading-edge research on the weather phenomena known as El Niño and La Niña, for example. He has also contributed greatly to our understanding of the Atlantic meridional overturning circulation (AMOC), one of the planet’s largest water circulation systems.

While much of Fedorov’s work focuses on long climate modeling over long timescales, he also is very much aware of the shorter-term impacts of a changing global climate — including the potential for stronger storms .

The 2024 Atlantic hurricane season began June 1 and goes until Nov. 30. The National Oceanic and Atmospheric Administration has predicted an 85% chance of an “above normal” season this year, with a projected 17 to 25 named storms (winds of 30 miles per hour or higher), including eight to 13 hurricanes (winds of 74 miles per hour or higher).

In an average season, there are 14 named storms and seven hurricanes.

Fedorov spoke with Yale News about the scientific underpinnings of hurricane season predictions and questions that still remain about how hurricanes form.

What are your thoughts on the recent predictions that the 2024 hurricane season in the U.S. will be more active than usual?

Alexey Fedorov: It is quite reasonable to expect a very active hurricane season in the Atlantic this year. Two main factors are at play: the main development region for hurricanes in the tropical North Atlantic, as well as the Caribbean Sea and the Gulf of Mexico, is already 2 to 3°C warmer than its long-term climatological temperature. At the same time, there is strong evidence of developing La Niña conditions in the Pacific, with anomalously cold sea surface temperatures along the equator in the eastern equatorial Pacific. La Niña typically increases the number of hurricanes in the Atlantic.

Why do El Niño/La Niña conditions have such a pronounced effect on the severity of storms?

Fedorov: El Niño — warm conditions in the equatorial Pacific — has a tendency to increase vertical wind shear in the North Atlantic, thus on average suppressing tropical cyclogenesis and reducing the number of hurricanes there. On the other hand, La Niña — cold conditions in the Pacific — reduces vertical wind shear in the Atlantic, thus increasing the number of hurricanes.

What other major factors contribute to stronger or weaker hurricane periods?

Fedorov: Persistently higher sea surface temperature in the tropical Atlantic and reduced vertical wind shear are the two main factors that facilitate tropical cyclogenesis. The former increases energy flow from the ocean to the atmosphere, while the latter helps the formation of tight vortices. Several climate modes affect these two variables. Specifically, the El Niño/La Niña cycle, as we just discussed, and on longer timescales the Atlantic Multidecadal Oscillation [AMO], also known as Atlantic Multidecadal Variability. The positive phase of the AMO implies decades of anomalously high ocean temperatures in the North Atlantic, and that’s on top of global warming.

Let’s talk about global warming. How does it affect hurricanes?

Fedorov: The effect of global warming on hurricanes and tropical cyclones in general is obviously a hot topic. There are many things we do understand: tropical cyclones will likely become more intense on average as the warmer atmosphere will hold more water vapor. They will survive for longer periods. They may be able to occur at higher latitudes than previously . The active hurricane season may lengthen. The most controversial issue, however, is whether the frequency of hurricanes will increase or not. This question is still debated.

What are the biggest remaining questions that climate scientists have about hurricane dynamics?

Fedorov: The question of hurricane frequency change with global warming is one of them. More generally, what sets the total number of tropical cyclones globally each year? Also, the impacts of the expected weakening of the Atlantic meridional overturning circulation — a major system of oceanic currents that include the Gulf Stream — on tropical cyclones. My research group has been working on the latter topic, and we already have some surprising results, indicating that we could expect more hurricanes along the U.S. eastern seaboard due to this weakening.

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