english essay green house effect

Essay on Greenhouse Effect for Students and Children

500 words essay on greenhouse effect.

The past month, July of 2019, has been the hottest month in the records of human history. This means on a global scale, the average climate and temperatures are now seen a steady rise year-on-year. The culprits of this climate change phenomenon are mainly pollution , overpopulation and general disregard for the environment by the human race. However, we can specifically point to two phenomenons that contribute to the rising temperatures – global warming and the greenhouse effect. Let us see more about them in this essay on the greenhouse effect.

The earth’s surface is surrounded by an envelope of the air we call the atmosphere. Gasses in this atmosphere trap the infrared radiation of the sun which generates heat on the surface of the earth. In an ideal scenario, this effect causes the temperature on the earth to be around 15c. And without such a phenomenon life could not sustain on earth.

However, due to rapid industrialization and rising pollution, the emission of greenhouse gases has increased multifold over the last few centuries. This, in turn, causes more radiation to be trapped in the earth’s atmosphere. And as a consequence, the temperature on the surface of the planet steadily rises. This is what we refer to when we talk about the man-made greenhouse effect.

Causes of Greenhouse Effect

As we saw earlier in this essay on the greenhouse effect, the phenomenon itself is naturally occurring and an important one to sustain life on our planet. However, there is an anthropogenic part of this effect. This is caused due to the activities of man.

The most prominent among this is the burning of fossil fuels . Our industries, vehicles, factories, etc are overly reliant on fossil fuels for their energy and power. This has caused an immense increase in emissions of harmful greenhouse gasses such as carbon dioxide, carbon monoxide, sulfides, etc. This has multiplied the greenhouse effect and we have seen a steady rise in surface temperatures.

Other harmful activities such as deforestation, excessive urbanization, harmful agricultural practices, etc. have also led to the release of excess carbon dioxide and made the greenhouse effect more prominent. Another harmful element that causes harm to the environment is CFC (chlorofluorocarbon).

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Some Effects of Greenhouse Effect

Even after overwhelming proof, there are still people who deny the existence of climate change and its devastating pitfalls. However, there are so many effects and pieces of evidence of climate change it is now undeniable. The surface temperature of the planet has risen by 1c since the 19th century. This change is largely due to the increased emissions of carbon dioxide. The most harm has been seen in the past 35 years in particular.

The oceans and the seas have absorbed a lot of this increased heat. The surfaces of these oceans have seen a rise in temperatures of 0.4c. The ice sheets and glaciers are also rapidly shrinking. The rate at which the ice caps melt in Antartica has tripled in the last decade itself. These alarming statistics and facts are proof of the major disaster we face in the form of climate change.

600 Words Essay on Greenhouse Effect

A Greenhouse , as the term suggests, is a structure made of glass which is designed to trap heat inside. Thus, even on cold chilling winter days, there is warmth inside it. Similarly, Earth also traps energy from the Sun and prevents it from escaping back. The greenhouse gases or the molecules present in the atmosphere of the Earth trap the heat of the Sun. This is what we know as the Greenhouse effect.

Greenhouse Gases

These gases or molecules are naturally present in the atmosphere of the Earth. However, they are also released due to human activities. These gases play a vital role in trapping the heat of the Sun and thereby gradually warming the temperature of Earth. The Earth is habitable for humans due to the equilibrium of the energy it receives and the energy that it reflects back to space.

Global Warming and the Greenhouse Effect

The trapping and emission of radiation by the greenhouse gases present in the atmosphere is known as the Greenhouse effect. Without this process, Earth will either be very cold or very hot, which will make life impossible on Earth.

The greenhouse effect is a natural phenomenon. Due to wrong human activities such as clearing forests, burning fossil fuels, releasing industrial gas in the atmosphere, etc., the emission of greenhouse gases is increasing.

Thus, this has, in turn, resulted in global warming . We can see the effects due to these like extreme droughts, floods, hurricanes, landslides, rise in sea levels, etc. Global warming is adversely affecting our biodiversity, ecosystem and the life of the people. Also, the Himalayan glaciers are melting due to this.

There are broadly two causes of the greenhouse effect:

I. Natural Causes

• Some components that are present on the Earth naturally produce greenhouse gases. For example, carbon dioxide is present in the oceans, decaying of plants due to forest fires and the manure of some animals produces methane , and nitrogen oxide is present in water and soil.
• Water Vapour raises the temperature by absorbing energy when there is a rise in the humidity.
• Humans and animals breathe oxygen and release carbon dioxide in the atmosphere.

II. Man-made Causes

• Burning of fossil fuels such as oil and coal emits carbon dioxide in the atmosphere which causes an excessive greenhouse effect. Also, while digging a coal mine or an oil well, methane is released from the Earth, which pollutes it.
• Trees with the help of the process of photosynthesis absorb the carbon dioxide and release oxygen. Due to deforestation the carbon dioxide level is continuously increasing. This is also a major cause of the increase in the greenhouse effect.
• In order to get maximum yield, the farmers use artificial nitrogen in their fields. This releases nitrogen oxide in the atmosphere.
• Industries release harmful gases in the atmosphere like methane, carbon dioxide , and fluorine gas. These also enhance global warming.

All the countries of the world are facing the ill effects of global warming. The Government and non-governmental organizations need to take appropriate and concrete measures to control the emission of toxic greenhouse gases. They need to promote the greater use of renewable energy and forestation. Also, it is the duty of every individual to protect the environment and not use such means that harm the atmosphere. It is the need of the hour to protect our environment else that day is not far away when life on Earth will also become difficult.

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The Greenhouse Effect and our Planet

The greenhouse effect happens when certain gases, which are known as greenhouse gases, accumulate in Earth’s atmosphere. Greenhouse gases include carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), ozone (O 3 ), and fluorinated gases.

Biology, Ecology, Earth Science, Geography, Human Geography

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The greenhouse effect happens when certain gases , which are known as greenhouse gases , accumulate in Earth’s atmosphere . Greenhouse gases include carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), ozone (O 3 ), and fluorinated gases.

Greenhouse gases allow the sun’s light to shine onto Earth’s surface, and then the gases , such as ozone , trap the heat that reflects back from the surface inside Earth’s atmosphere . The gases act like the glass walls of a  greenhouse —thus the name, greenhouse gas .

According to scientists, the average temperature of Earth would drop from 14˚C (57˚F) to as low as –18˚C (–0.4˚F), without the greenhouse effect .

Some greenhouse gases come from natural sources, for example, evaporation  adds water vapor to the atmosphere . Animals and plants release carbon dioxide when they respire, or breathe. Methane is released naturally from decomposition. There is evidence that suggests methane is released in low-oxygen environments , such as  swamps or landfills . Volcanoes —both on land and under the ocean —release greenhouse gases , so periods of high volcanic activity tend to be warmer.

Since the  Industrial Revolution  of the late 1700s and early 1800s, people have been releasing larger quantities of greenhouse gases into the atmosphere. That amount has skyrocketed in the past century. Greenhouse gas emissions increased 70 percent between 1970 and 2004. Emissions of CO 2 , rose by about 80 percent during that time.

The amount of CO 2 in the atmosphere far exceeds the naturally occurring range seen during the last 650,000 years.

Most of the CO 2 that people put into the atmosphere comes from burning  fossil fuels . Cars, trucks, t rains , and planes all burn fossil fuels. Many electric power plants do as well. Another way humans release CO 2 into the atmosphere is by cutting down  forests , because trees contain large amounts of carbon.

People add methane to the atmosphere through  livestock  farming, landfills , and fossil fuel production such as  coal mining  and natural gas processing. Nitrous oxide comes from  agriculture  and fossil fuel burning. Fluorinated gases include chlorofluoro carbons (CFCs),  hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). They are produced during the manufacturing of refrigeration and cooling products and through aerosols.

All of these human activities add greenhouse gases to the atmosphere . As the level of these gases rises, so does the  temperature  of Earth. The rise in Earth’s average temperature contributed to by human activity is known as  global warming .

The Greenhouse Effect and Climate Change Even slight increases in average global temperatures can have huge effects.

Perhaps the biggest, most obvious effect is that  glaciers and  ice caps melt faster than usual. The  meltwater  d rains into the oceans , causing  sea levels to rise.

Glaciers and ice caps cover about 10 percent of the world’s landmasses. They hold between 70 and 75 percent of the world’s  freshwater . If all of this ice melted, sea levels would rise by about 70 meters (230 feet).

The Intergovernmental Panel on Climate Change states that the global sea level rose about 1.8 millimeters (0.07 inches) per year from 1961 to 1993, and about 3.1 millimeters (0.12 inches) per year since 1993.

Rising sea levels cause  flooding in  coastal cities, which could displace millions of people in low-lying areas such as Bangladesh, the U.S. state of Florida, and the Netherlands.

Millions more people in countries like Bolivia, Peru, and India depend on glacial meltwater for drinking,  irrigation , and  hydroelectric power . Rapid loss of these glaciers would devastate those countries.

Greenhouse gas emissions affect more than just temperature . Another effect involves changes in  precipitation , such as  rain  and  snow .

Over the course of the 20th century, precipitation increased in eastern parts of North and South America, northern Europe, and northern and central Asia. However, it has decreased in parts of Africa, the Mediterranean, and southern Asia.

As climates change, so do the habitats for living things. Animals that are adapted to a certain  climate  may become threatened. Many human societies depend on predictable rain patterns in order to grow specific  crops for food, clothing, and trade. If the climate of an area changes, the people who live there may no longer be able to grow the crops they depend on for survival. Some scientists also worry that tropical diseases will expand their ranges into what are now more temperate regions if the temperatures of those areas increase.

Most climate scientists agree that we must reduce the amount of greenhouse gases released into the atmosphere. Ways to do this, include:

• driving less, using public transportation , carpooling, walking, or riding a bike.
• flying less—airplanes produce huge amounts of greenhouse gas emissions.
• reducing, reusing, and recycling.
• planting a tree—trees absorb carbon dioxide, keeping it out of the atmosphere.
• using less  electricity .
• eating less meat—cows are one of the biggest methane producers.
• supporting alternative energy sources that don’t burn fossil fuels.

Artificial Gas

Chlorofluorocarbons (CFCs) are the only greenhouse gases not created by nature. They are created through refrigeration and aerosol cans.

CFCs, used mostly as refrigerants, are chemicals that were developed in the late 19th century and came into wide use in the mid-20th century.

Other greenhouse gases, such as carbon dioxide, are emitted by human activity, at an unnatural and unsustainable level, but the molecules do occur naturally in Earth's atmosphere.

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Related Resources

Understanding Global Change

Discover why the climate and environment changes, your place in the Earth system, and paths to a resilient future.

Greenhouse effect

Life as we know it would be impossible if not for the greenhouse effect, the process through which heat is absorbed and re-radiated in that atmosphere. The intensity of a planet’s greenhouse effect is determined by the relative abundance of greenhouse gases in its atmosphere. Without greenhouse gases, most of Earth’s heat would be lost to outer space, and our planet would quickly turn into a giant ball of ice. Increase the amount of greenhouse gases to the levels found on the planet Venus, and the Earth would be as hot as a pizza oven! Fortunately, the strength of Earth’s greenhouse effect keeps our planet within a temperature range that supports life

On this page

What is the greenhouse effect, earth system models about the greenhouse effect, how human activities influence the greenhouse effect, explore the earth system, investigate, links to learn more.

For the classroom:

• Teaching Resources

Global Change Infographic

The greenhouse effect occurs in the atmosphere, and is an essential part of How the Earth System Works. Click the image on the left to open the Understanding Global Change Infographic . Locate the greenhouse effect icon and identify other topics that cause changes to, or are affected by, the greenhouse effect.

Adapted from the Environmental Protection Agency greenhouse effect file

Greenhouse gases such as methane, carbon dioxide, nitrous oxide, and water vapor  significantly affect the amount of energy in the Earth system, even though they make up a tiny percentage of Earth’s atmosphere.  Solar radiation that passes through the atmosphere and reaches Earth’s surface is either reflected or absorbed . Reflected sunlight doesn’t add any heat to the Earth system because this energy bounces back into space.

However, absorbed sunlight increases the temperature of Earth’s surface, and the warmed surface re-radiates as long-wave radiation (also known as infrared radiation). Infrared radiation is invisible to the eye, but we feel it as heat.

If there were not any greenhouse gases in the atmosphere, all that heat would pass directly back into space. With greenhouse gases present, however, most of the long-wave radiation coming from Earth’s surface is absorbed and then re-radiated in all directions many times before passing back into space. Heat that is re-radiated downward, toward the Earth, is absorbed by the surface and re-radiated again.

Clouds also influence the greenhouse effect. A thick, low cloud cover can enhance the reflectivity of the atmosphere, reducing the amount of solar radiation reaching Earth’s surface, but clouds high in the atmosphere can intensify the greenhouse effect by re-radiating heat from the Earth’s surface.

Altogether, this cycle of absorption and re-radiation by greenhouse gases impedes the loss of heat from our atmosphere to space, creating the greenhouse effect. Increases in the amount of greenhouses gases will mean that more heat is trapped, increasing the amount of energy in the Earth system (Earth’s energy budget), and raising Earth’s temperature. This increase in Earth’s average temperature is also known as global warming.

This Earth system model is one way to represent the essential processes and interactions related to the greenhouse effect. Hover over the icons for brief explanations; click on the icons to learn more about each topic. Download the Earth system models on this page. There are a few ways that the relationships among these topics can be represented and explained using the Understanding Global Change icons ( download examples ).  

The greenhouse effect, which influences Earth’s average temperature, affects many of the processes that shape global climate and ecosystems.  This model shows some of the other parts of the Earth system that the greenhouse effect influences, including the water cycle and water temperature .

Humans directly affect the greenhouse effect through activities that result in greenhouse gas emissions. The Earth system model below includes some of the ways that human activities increase the amount of greenhouse gases in the atmosphere. Releasing greenhouse gases intensifies the greenhouse effect, and increases Earth’s average air temperatures (also known as global warming). Hover over or click on the icons to learn more about these human causes of change and how they influence the greenhouse effect.

Click the scene icons and bolded terms on this page to learn more about these process and phenomena.

Learn more in these real-world examples, and challenge yourself to  construct a model  that explains the Earth system relationships.

• Ancient fossils and modern climate change
• How Global Warming Works
• NASA:  Global Climate Change:  A Blanket Around the Earth
• UCAR Center for Science Education: The Greenhouse Effect
• IPCC:  What is the Greenhouse Effect?
• Indicators of Change (NCA.2014)
• Human influence on the greenhouse effect
• The Carbon Cycle and Earth’s Climate

What Is the Greenhouse Effect?

Watch this video to learn about the greenhouse effect! Click here to download this video (1920x1080, 105 MB, video/mp4). Click here to download this video about the greenhouse effect in Spanish (1920x1080, 154 MB, video/mp4).

How does the greenhouse effect work?

As you might expect from the name, the greenhouse effect works … like a greenhouse! A greenhouse is a building with glass walls and a glass roof. Greenhouses are used to grow plants, such as tomatoes and tropical flowers.

A greenhouse stays warm inside, even during the winter. In the daytime, sunlight shines into the greenhouse and warms the plants and air inside. At nighttime, it's colder outside, but the greenhouse stays pretty warm inside. That's because the glass walls of the greenhouse trap the Sun's heat.

A greenhouse captures heat from the Sun during the day. Its glass walls trap the Sun's heat, which keeps plants inside the greenhouse warm — even on cold nights. Credit: NASA/JPL-Caltech

The greenhouse effect works much the same way on Earth. Gases in the atmosphere, such as carbon dioxide , trap heat similar to the glass roof of a greenhouse. These heat-trapping gases are called greenhouse gases .

During the day, the Sun shines through the atmosphere. Earth's surface warms up in the sunlight. At night, Earth's surface cools, releasing heat back into the air. But some of the heat is trapped by the greenhouse gases in the atmosphere. That's what keeps our Earth a warm and cozy 58 degrees Fahrenheit (14 degrees Celsius), on average.

Earth's atmosphere traps some of the Sun's heat, preventing it from escaping back into space at night. Credit: NASA/JPL-Caltech

How are humans impacting the greenhouse effect?

Human activities are changing Earth's natural greenhouse effect. Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere.

NASA has observed increases in the amount of carbon dioxide and some other greenhouse gases in our atmosphere. Too much of these greenhouse gases can cause Earth's atmosphere to trap more and more heat. This causes Earth to warm up.

What reduces the greenhouse effect on Earth?

Just like a glass greenhouse, Earth's greenhouse is also full of plants! Plants can help to balance the greenhouse effect on Earth. All plants — from giant trees to tiny phytoplankton in the ocean — take in carbon dioxide and give off oxygen.

The ocean also absorbs a lot of excess carbon dioxide in the air. Unfortunately, the increased carbon dioxide in the ocean changes the water, making it more acidic. This is called ocean acidification .

More acidic water can be harmful to many ocean creatures, such as certain shellfish and coral. Warming oceans — from too many greenhouse gases in the atmosphere — can also be harmful to these organisms. Warmer waters are a main cause of coral bleaching .

This photograph shows a bleached brain coral. A main cause of coral bleaching is warming oceans. Ocean acidification also stresses coral reef communities. Credit: NOAA

• ENVIRONMENT

What is global warming, explained

The planet is heating up—and fast.

Glaciers are melting , sea levels are rising, cloud forests are dying , and wildlife is scrambling to keep pace. It has become clear that humans have caused most of the past century's warming by releasing heat-trapping gases as we power our modern lives. Called greenhouse gases, their levels are higher now than at any time in the last 800,000 years .

We often call the result global warming, but it is causing a set of changes to the Earth's climate, or long-term weather patterns, that varies from place to place. While many people think of global warming and climate change as synonyms , scientists use “climate change” when describing the complex shifts now affecting our planet’s weather and climate systems—in part because some areas actually get cooler in the short term.

Climate change encompasses not only rising average temperatures but also extreme weather events , shifting wildlife populations and habitats, rising seas , and a range of other impacts. All of those changes are emerging as humans continue to add heat-trapping greenhouse gases to the atmosphere, changing the rhythms of climate that all living things have come to rely on.

What will we do—what can we do—to slow this human-caused warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the fate of the Earth as we know it—coasts, forests, farms, and snow-capped mountains—hangs in the balance.

Understanding the greenhouse effect

The "greenhouse effect" is the warming that happens when certain gases in Earth's atmosphere trap heat . These gases let in light but keep heat from escaping, like the glass walls of a greenhouse, hence the name.

Sunlight shines onto the Earth's surface, where the energy is absorbed and then radiate back into the atmosphere as heat. In the atmosphere, greenhouse gas molecules trap some of the heat, and the rest escapes into space. The more greenhouse gases concentrate in the atmosphere, the more heat gets locked up in the molecules.

For Hungry Minds

Scientists have known about the greenhouse effect since 1824, when Joseph Fourier calculated that the Earth would be much colder if it had no atmosphere. This natural greenhouse effect is what keeps the Earth's climate livable. Without it, the Earth's surface would be an average of about 60 degrees Fahrenheit (33 degrees Celsius) cooler.

A polar bear stands sentinel on Rudolf Island in Russia’s Franz Josef Land archipelago, where the perennial ice is melting.

In 1895, the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide , a greenhouse gas. He kicked off 100 years of climate research that has given us a sophisticated understanding of global warming.

Levels of greenhouse gases have gone up and down over the Earth's history, but they had been fairly constant for the past few thousand years. Global average temperatures had also stayed fairly constant over that time— until the past 150 years . Through the burning of fossil fuels and other activities that have emitted large amounts of greenhouse gases, particularly over the past few decades, humans are now enhancing the greenhouse effect and warming Earth significantly, and in ways that promise many effects , scientists warn.

Aren't temperature changes natural?

Human activity isn't the only factor that affects Earth's climate. Volcanic eruptions and variations in solar radiation from sunspots, solar wind, and the Earth's position relative to the sun also play a role. So do large-scale weather patterns such as El Niño .

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But climate models that scientists use to monitor Earth’s temperatures take those factors into account. Changes in solar radiation levels as well as minute particles suspended in the atmosphere from volcanic eruptions , for example, have contributed only about two percent to the recent warming effect. The balance comes from greenhouse gases and other human-caused factors, such as land use change .

The short timescale of this recent warming is singular as well. Volcanic eruptions , for example, emit particles that temporarily cool the Earth's surface. But their effect lasts just a few years. Events like El Niño also work on fairly short and predictable cycles. On the other hand, the types of global temperature fluctuations that have contributed to ice ages occur on a cycle of hundreds of thousands of years.

For thousands of years now, emissions of greenhouse gases to the atmosphere have been balanced out by greenhouse gases that are naturally absorbed. As a result, greenhouse gas concentrations and temperatures have been fairly stable, which has allowed human civilization to flourish within a consistent climate.

Greenland is covered with a vast amount of ice—but the ice is melting four times faster than thought, suggesting that Greenland may be approaching a dangerous tipping point, with implications for global sea-level rise.

Now, humans have increased the amount of carbon dioxide in the atmosphere by more than a third since the Industrial Revolution. Changes that have historically taken thousands of years are now happening over the course of decades .

Why does this matter?

The rapid rise in greenhouse gases is a problem because it’s changing the climate faster than some living things can adapt to. Also, a new and more unpredictable climate poses unique challenges to all life.

Historically, Earth's climate has regularly shifted between temperatures like those we see today and temperatures cold enough to cover much of North America and Europe with ice. The difference between average global temperatures today and during those ice ages is only about 9 degrees Fahrenheit (5 degrees Celsius), and the swings have tended to happen slowly, over hundreds of thousands of years.

But with concentrations of greenhouse gases rising, Earth's remaining ice sheets such as Greenland and Antarctica are starting to melt too . That extra water could raise sea levels significantly, and quickly. By 2050, sea levels are predicted to rise between one and 2.3 feet as glaciers melt.

As the mercury rises, the climate can change in unexpected ways. In addition to sea levels rising, weather can become more extreme . This means more intense major storms, more rain followed by longer and drier droughts—a challenge for growing crops—changes in the ranges in which plants and animals can live, and loss of water supplies that have historically come from glaciers.

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3.2: The Greenhouse Effect

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• Page ID 36543

• Laci M. Gerhart-Barley
• College of Biological Sciences - UC Davis

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The process by which the atmosphere absorbs the sun’s energy and prevents it from being radiated back out to space has often been compared to that of a greenhouse, leading to the nickname the greenhouse effect . It is the same process that occurs when you leave your car sitting in the sun with the windows rolled up. The sun’s rays are powerful enough to pass through the glass of the windows (or through the Earth’s atmosphere) and be absorbed by the dashboard and seats (or the Earth’s surface); however, when these surfaces emit energy, it is not powerful enough to pass back out through the window glass (or atmosphere) and in so doing becomes trapped within the car (or atmosphere) causing it to warm. There are certain atmospheric gases, termed greenhouses gases (or GHGs) that behave like the car windows, increasing the amount of energy retained in the atmosphere, and increasing the amount of warming that occurs. In Figure 3.1.1 the greenhouse effect is represented by the curved arrow showing 95% of the energy emitted by the Earth’s surface that is reabsorbed, and the amount of GHGs in the atmosphere drive the size of this arrow.

The primary GHGs considered in this section are carbon dioxide (CO 2 ), methane (CH 3 ), and nitrous oxide (N 2 O). Scientists at the National Oceanic and Atmospheric Administration (NOAA) have been tracking concentrations of these and other GHGs in the atmosphere for decades (Fig 3.2.1) and have found that all three continue to steadily increase.

These increases are particularly pronounced when compared to past GHG concentrations. Scientists can measure past atmospheric composition in ice sheets in Greenland and Antarctica. As the ice sheets formed, small bubbles of air were trapped in the ice, and coring deep into the ice sheet (Fig 3.2.2a) allows scientists to reconstruct atmospheric composition from direct measurements as far back as 800,000 years (Fig 3.2.2b). From these measurements, we can see that atmospheric CO 2 levels (and temperature, as estimated from oxygen isotope composition of the ice itself) have fluctuated significantly throughout the past. The ice sheets document a clear pattern of periodic increases and decreases in CO 2 , which are coupled with increases and decreases in temperature. Periods of low CO 2 and low temperatures are glacial periods (also referred to as ‘ice ages’), and periods of high CO 2 and high temperature are inter-glacial periods. For the past 800,000 years, Earth has oscillated between glacial and inter-glacial periods roughly every 100,000 years. The maximum level that CO 2 concentrations reached in the last 800,000 years was approximately 300 parts per million (ppm). Global CO 2 levels are now over 400 ppm, a level that scientists estimate has not occurred on Earth since the Pliocene Epoch, approximately 3 million years ago.

This increase in CO 2 (as well as other GHGs) increases the amount of solar energy that is retained in the atmosphere as opposed to radiated back out to space, which increases the temperature of the Earth’s surface. Figure 3.2.3 shows the temperature anomaly for the decade 2014-2018 as compared to the average from 1951-1980. The National Aeronautics and Space Administration (NASA) reports that the global average temperature has increased approximately 1.4° Fahrenheit (0.8° C) since 1880, though that warming has not been evenly distributed across the Earth. As can be seen in Figure 3.2.3, the polar regions, particularly the Arctic, have warmed much more than other areas. This pattern is particularly concerning given the feedbacks that warming in polar regions may have on the melting of ice sheets and sea ice.

In 2018, the state of California released its Fourth Climate Change Assessment report, which outlines the impact that global climatic changes are having and will have on the state (Fig 3.2.4). Some regions, most notably southern California, have already experienced nearly 3°F increases in annual average temperatures since the beginning of the 20th century.

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By Julia Rosen

Ms. Rosen is a journalist with a Ph.D. in geology. Her research involved studying ice cores from Greenland and Antarctica to understand past climate changes.

• Published April 19, 2021 Updated Nov. 6, 2021

The science of climate change is more solid and widely agreed upon than you might think. But the scope of the topic, as well as rampant disinformation, can make it hard to separate fact from fiction. Here, we’ve done our best to present you with not only the most accurate scientific information, but also an explanation of how we know it.

How do we know climate change is really happening?

How much agreement is there among scientists about climate change, do we really only have 150 years of climate data how is that enough to tell us about centuries of change, how do we know climate change is caused by humans, since greenhouse gases occur naturally, how do we know they’re causing earth’s temperature to rise, why should we be worried that the planet has warmed 2°f since the 1800s, is climate change a part of the planet’s natural warming and cooling cycles, how do we know global warming is not because of the sun or volcanoes, how can winters and certain places be getting colder if the planet is warming, wildfires and bad weather have always happened. how do we know there’s a connection to climate change, how bad are the effects of climate change going to be, what will it cost to do something about climate change, versus doing nothing.

Climate change is often cast as a prediction made by complicated computer models. But the scientific basis for climate change is much broader, and models are actually only one part of it (and, for what it’s worth, they’re surprisingly accurate ).

For more than a century , scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming. These gases make up just a small fraction of the atmosphere but exert outsized control on Earth’s climate by trapping some of the planet’s heat before it escapes into space. This greenhouse effect is important: It’s why a planet so far from the sun has liquid water and life!

However, during the Industrial Revolution, people started burning coal and other fossil fuels to power factories, smelters and steam engines, which added more greenhouse gases to the atmosphere. Ever since, human activities have been heating the planet.

We know this is true thanks to an overwhelming body of evidence that begins with temperature measurements taken at weather stations and on ships starting in the mid-1800s. Later, scientists began tracking surface temperatures with satellites and looking for clues about climate change in geologic records. Together, these data all tell the same story: Earth is getting hotter.

Average global temperatures have increased by 2.2 degrees Fahrenheit, or 1.2 degrees Celsius, since 1880, with the greatest changes happening in the late 20th century. Land areas have warmed more than the sea surface and the Arctic has warmed the most — by more than 4 degrees Fahrenheit just since the 1960s. Temperature extremes have also shifted. In the United States, daily record highs now outnumber record lows two-to-one.

Where it was cooler or warmer in 2020 compared with the middle of the 20th century

This warming is unprecedented in recent geologic history. A famous illustration, first published in 1998 and often called the hockey-stick graph, shows how temperatures remained fairly flat for centuries (the shaft of the stick) before turning sharply upward (the blade). It’s based on data from tree rings, ice cores and other natural indicators. And the basic picture , which has withstood decades of scrutiny from climate scientists and contrarians alike, shows that Earth is hotter today than it’s been in at least 1,000 years, and probably much longer.

In fact, surface temperatures actually mask the true scale of climate change, because the ocean has absorbed 90 percent of the heat trapped by greenhouse gases . Measurements collected over the last six decades by oceanographic expeditions and networks of floating instruments show that every layer of the ocean is warming up. According to one study , the ocean has absorbed as much heat between 1997 and 2015 as it did in the previous 130 years.

We also know that climate change is happening because we see the effects everywhere. Ice sheets and glaciers are shrinking while sea levels are rising. Arctic sea ice is disappearing. In the spring, snow melts sooner and plants flower earlier. Animals are moving to higher elevations and latitudes to find cooler conditions. And droughts, floods and wildfires have all gotten more extreme. Models predicted many of these changes, but observations show they are now coming to pass.

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There’s no denying that scientists love a good, old-fashioned argument. But when it comes to climate change, there is virtually no debate: Numerous studies have found that more than 90 percent of scientists who study Earth’s climate agree that the planet is warming and that humans are the primary cause. Most major scientific bodies, from NASA to the World Meteorological Organization , endorse this view. That’s an astounding level of consensus given the contrarian, competitive nature of the scientific enterprise, where questions like what killed the dinosaurs remain bitterly contested .

Scientific agreement about climate change started to emerge in the late 1980s, when the influence of human-caused warming began to rise above natural climate variability. By 1991, two-thirds of earth and atmospheric scientists surveyed for an early consensus study said that they accepted the idea of anthropogenic global warming. And by 1995, the Intergovernmental Panel on Climate Change, a famously conservative body that periodically takes stock of the state of scientific knowledge, concluded that “the balance of evidence suggests that there is a discernible human influence on global climate.” Currently, more than 97 percent of publishing climate scientists agree on the existence and cause of climate change (as does nearly 60 percent of the general population of the United States).

So where did we get the idea that there’s still debate about climate change? A lot of it came from coordinated messaging campaigns by companies and politicians that opposed climate action. Many pushed the narrative that scientists still hadn’t made up their minds about climate change, even though that was misleading. Frank Luntz, a Republican consultant, explained the rationale in an infamous 2002 memo to conservative lawmakers: “Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly,” he wrote. Questioning consensus remains a common talking point today, and the 97 percent figure has become something of a lightning rod .

To bolster the falsehood of lingering scientific doubt, some people have pointed to things like the Global Warming Petition Project, which urged the United States government to reject the Kyoto Protocol of 1997, an early international climate agreement. The petition proclaimed that climate change wasn’t happening, and even if it were, it wouldn’t be bad for humanity. Since 1998, more than 30,000 people with science degrees have signed it. However, nearly 90 percent of them studied something other than Earth, atmospheric or environmental science, and the signatories included just 39 climatologists. Most were engineers, doctors, and others whose training had little to do with the physics of the climate system.

A few well-known researchers remain opposed to the scientific consensus. Some, like Willie Soon, a researcher affiliated with the Harvard-Smithsonian Center for Astrophysics, have ties to the fossil fuel industry . Others do not, but their assertions have not held up under the weight of evidence. At least one prominent skeptic, the physicist Richard Muller, changed his mind after reassessing historical temperature data as part of the Berkeley Earth project. His team’s findings essentially confirmed the results he had set out to investigate, and he came away firmly convinced that human activities were warming the planet. “Call me a converted skeptic,” he wrote in an Op-Ed for the Times in 2012.

Mr. Luntz, the Republican pollster, has also reversed his position on climate change and now advises politicians on how to motivate climate action.

A final note on uncertainty: Denialists often use it as evidence that climate science isn’t settled. However, in science, uncertainty doesn’t imply a lack of knowledge. Rather, it’s a measure of how well something is known. In the case of climate change, scientists have found a range of possible future changes in temperature, precipitation and other important variables — which will depend largely on how quickly we reduce emissions. But uncertainty does not undermine their confidence that climate change is real and that people are causing it.

Earth’s climate is inherently variable. Some years are hot and others are cold, some decades bring more hurricanes than others, some ancient droughts spanned the better part of centuries. Glacial cycles operate over many millenniums. So how can scientists look at data collected over a relatively short period of time and conclude that humans are warming the planet? The answer is that the instrumental temperature data that we have tells us a lot, but it’s not all we have to go on.

Historical records stretch back to the 1880s (and often before), when people began to regularly measure temperatures at weather stations and on ships as they traversed the world’s oceans. These data show a clear warming trend during the 20th century.

Global average temperature compared with the middle of the 20th century

+0.75°C

–0.25°

Some have questioned whether these records could be skewed, for instance, by the fact that a disproportionate number of weather stations are near cities, which tend to be hotter than surrounding areas as a result of the so-called urban heat island effect. However, researchers regularly correct for these potential biases when reconstructing global temperatures. In addition, warming is corroborated by independent data like satellite observations, which cover the whole planet, and other ways of measuring temperature changes.

Much has also been made of the small dips and pauses that punctuate the rising temperature trend of the last 150 years. But these are just the result of natural climate variability or other human activities that temporarily counteract greenhouse warming. For instance, in the mid-1900s, internal climate dynamics and light-blocking pollution from coal-fired power plants halted global warming for a few decades. (Eventually, rising greenhouse gases and pollution-control laws caused the planet to start heating up again.) Likewise, the so-called warming hiatus of the 2000s was partly a result of natural climate variability that allowed more heat to enter the ocean rather than warm the atmosphere. The years since have been the hottest on record .

Still, could the entire 20th century just be one big natural climate wiggle? To address that question, we can look at other kinds of data that give a longer perspective. Researchers have used geologic records like tree rings, ice cores, corals and sediments that preserve information about prehistoric climates to extend the climate record. The resulting picture of global temperature change is basically flat for centuries, then turns sharply upward over the last 150 years. It has been a target of climate denialists for decades. However, study after study has confirmed the results , which show that the planet hasn’t been this hot in at least 1,000 years, and probably longer.

Scientists have studied past climate changes to understand the factors that can cause the planet to warm or cool. The big ones are changes in solar energy, ocean circulation, volcanic activity and the amount of greenhouse gases in the atmosphere. And they have each played a role at times.

For example, 300 years ago, a combination of reduced solar output and increased volcanic activity cooled parts of the planet enough that Londoners regularly ice skated on the Thames . About 12,000 years ago, major changes in Atlantic circulation plunged the Northern Hemisphere into a frigid state. And 56 million years ago, a giant burst of greenhouse gases, from volcanic activity or vast deposits of methane (or both), abruptly warmed the planet by at least 9 degrees Fahrenheit, scrambling the climate, choking the oceans and triggering mass extinctions.

In trying to determine the cause of current climate changes, scientists have looked at all of these factors . The first three have varied a bit over the last few centuries and they have quite likely had modest effects on climate , particularly before 1950. But they cannot account for the planet’s rapidly rising temperature, especially in the second half of the 20th century, when solar output actually declined and volcanic eruptions exerted a cooling effect.

That warming is best explained by rising greenhouse gas concentrations . Greenhouse gases have a powerful effect on climate (see the next question for why). And since the Industrial Revolution, humans have been adding more of them to the atmosphere, primarily by extracting and burning fossil fuels like coal, oil and gas, which releases carbon dioxide.

Bubbles of ancient air trapped in ice show that, before about 1750, the concentration of carbon dioxide in the atmosphere was roughly 280 parts per million. It began to rise slowly and crossed the 300 p.p.m. threshold around 1900. CO2 levels then accelerated as cars and electricity became big parts of modern life, recently topping 420 p.p.m . The concentration of methane, the second most important greenhouse gas, has more than doubled. We’re now emitting carbon much faster than it was released 56 million years ago .

30 billion metric tons

Carbon dioxide emitted worldwide 1850-2017

Rest of world

Other developed

European Union

Developed economies

Other countries

United States

E.U. and U.K.

These rapid increases in greenhouse gases have caused the climate to warm abruptly. In fact, climate models suggest that greenhouse warming can explain virtually all of the temperature change since 1950. According to the most recent report by the Intergovernmental Panel on Climate Change, which assesses published scientific literature, natural drivers and internal climate variability can only explain a small fraction of late-20th century warming.

Another study put it this way: The odds of current warming occurring without anthropogenic greenhouse gas emissions are less than 1 in 100,000 .

But greenhouse gases aren’t the only climate-altering compounds people put into the air. Burning fossil fuels also produces particulate pollution that reflects sunlight and cools the planet. Scientists estimate that this pollution has masked up to half of the greenhouse warming we would have otherwise experienced.

Greenhouse gases like water vapor and carbon dioxide serve an important role in the climate. Without them, Earth would be far too cold to maintain liquid water and humans would not exist!

Here’s how it works: the planet’s temperature is basically a function of the energy the Earth absorbs from the sun (which heats it up) and the energy Earth emits to space as infrared radiation (which cools it down). Because of their molecular structure, greenhouse gases temporarily absorb some of that outgoing infrared radiation and then re-emit it in all directions, sending some of that energy back toward the surface and heating the planet . Scientists have understood this process since the 1850s .

Greenhouse gas concentrations have varied naturally in the past. Over millions of years, atmospheric CO2 levels have changed depending on how much of the gas volcanoes belched into the air and how much got removed through geologic processes. On time scales of hundreds to thousands of years, concentrations have changed as carbon has cycled between the ocean, soil and air.

Today, however, we are the ones causing CO2 levels to increase at an unprecedented pace by taking ancient carbon from geologic deposits of fossil fuels and putting it into the atmosphere when we burn them. Since 1750, carbon dioxide concentrations have increased by almost 50 percent. Methane and nitrous oxide, other important anthropogenic greenhouse gases that are released mainly by agricultural activities, have also spiked over the last 250 years.

We know based on the physics described above that this should cause the climate to warm. We also see certain telltale “fingerprints” of greenhouse warming. For example, nights are warming even faster than days because greenhouse gases don’t go away when the sun sets. And upper layers of the atmosphere have actually cooled, because more energy is being trapped by greenhouse gases in the lower atmosphere.

We also know that we are the cause of rising greenhouse gas concentrations — and not just because we can measure the CO2 coming out of tailpipes and smokestacks. We can see it in the chemical signature of the carbon in CO2.

Carbon comes in three different masses: 12, 13 and 14. Things made of organic matter (including fossil fuels) tend to have relatively less carbon-13. Volcanoes tend to produce CO2 with relatively more carbon-13. And over the last century, the carbon in atmospheric CO2 has gotten lighter, pointing to an organic source.

We can tell it’s old organic matter by looking for carbon-14, which is radioactive and decays over time. Fossil fuels are too ancient to have any carbon-14 left in them, so if they were behind rising CO2 levels, you would expect the amount of carbon-14 in the atmosphere to drop, which is exactly what the data show .

It’s important to note that water vapor is the most abundant greenhouse gas in the atmosphere. However, it does not cause warming; instead it responds to it . That’s because warmer air holds more moisture, which creates a snowball effect in which human-caused warming allows the atmosphere to hold more water vapor and further amplifies climate change. This so-called feedback cycle has doubled the warming caused by anthropogenic greenhouse gas emissions.

A common source of confusion when it comes to climate change is the difference between weather and climate. Weather is the constantly changing set of meteorological conditions that we experience when we step outside, whereas climate is the long-term average of those conditions, usually calculated over a 30-year period. Or, as some say: Weather is your mood and climate is your personality.

So while 2 degrees Fahrenheit doesn’t represent a big change in the weather, it’s a huge change in climate. As we’ve already seen, it’s enough to melt ice and raise sea levels, to shift rainfall patterns around the world and to reorganize ecosystems, sending animals scurrying toward cooler habitats and killing trees by the millions.

It’s also important to remember that two degrees represents the global average, and many parts of the world have already warmed by more than that. For example, land areas have warmed about twice as much as the sea surface. And the Arctic has warmed by about 5 degrees. That’s because the loss of snow and ice at high latitudes allows the ground to absorb more energy, causing additional heating on top of greenhouse warming.

Relatively small long-term changes in climate averages also shift extremes in significant ways. For instance, heat waves have always happened, but they have shattered records in recent years. In June of 2020, a town in Siberia registered temperatures of 100 degrees . And in Australia, meteorologists have added a new color to their weather maps to show areas where temperatures exceed 125 degrees. Rising sea levels have also increased the risk of flooding because of storm surges and high tides. These are the foreshocks of climate change.

And we are in for more changes in the future — up to 9 degrees Fahrenheit of average global warming by the end of the century, in the worst-case scenario . For reference, the difference in global average temperatures between now and the peak of the last ice age, when ice sheets covered large parts of North America and Europe, is about 11 degrees Fahrenheit.

Under the Paris Climate Agreement, which President Biden recently rejoined, countries have agreed to try to limit total warming to between 1.5 and 2 degrees Celsius, or 2.7 and 3.6 degrees Fahrenheit, since preindustrial times. And even this narrow range has huge implications . According to scientific studies, the difference between 2.7 and 3.6 degrees Fahrenheit will very likely mean the difference between coral reefs hanging on or going extinct, and between summer sea ice persisting in the Arctic or disappearing completely. It will also determine how many millions of people suffer from water scarcity and crop failures, and how many are driven from their homes by rising seas. In other words, one degree Fahrenheit makes a world of difference.

Earth’s climate has always changed. Hundreds of millions of years ago, the entire planet froze . Fifty million years ago, alligators lived in what we now call the Arctic . And for the last 2.6 million years, the planet has cycled between ice ages when the planet was up to 11 degrees cooler and ice sheets covered much of North America and Europe, and milder interglacial periods like the one we’re in now.

Climate denialists often point to these natural climate changes as a way to cast doubt on the idea that humans are causing climate to change today. However, that argument rests on a logical fallacy. It’s like “seeing a murdered body and concluding that people have died of natural causes in the past, so the murder victim must also have died of natural causes,” a team of social scientists wrote in The Debunking Handbook , which explains the misinformation strategies behind many climate myths.

Indeed, we know that different mechanisms caused the climate to change in the past. Glacial cycles, for example, were triggered by periodic variations in Earth’s orbit , which take place over tens of thousands of years and change how solar energy gets distributed around the globe and across the seasons.

These orbital variations don’t affect the planet’s temperature much on their own. But they set off a cascade of other changes in the climate system; for instance, growing or melting vast Northern Hemisphere ice sheets and altering ocean circulation. These changes, in turn, affect climate by altering the amount of snow and ice, which reflect sunlight, and by changing greenhouse gas concentrations. This is actually part of how we know that greenhouse gases have the ability to significantly affect Earth’s temperature.

For at least the last 800,000 years , atmospheric CO2 concentrations oscillated between about 180 parts per million during ice ages and about 280 p.p.m. during warmer periods, as carbon moved between oceans, forests, soils and the atmosphere. These changes occurred in lock step with global temperatures, and are a major reason the entire planet warmed and cooled during glacial cycles, not just the frozen poles.

Today, however, CO2 levels have soared to 420 p.p.m. — the highest they’ve been in at least three million years . The concentration of CO2 is also increasing about 100 times faster than it did at the end of the last ice age. This suggests something else is going on, and we know what it is: Since the Industrial Revolution, humans have been burning fossil fuels and releasing greenhouse gases that are heating the planet now (see Question 5 for more details on how we know this, and Questions 4 and 8 for how we know that other natural forces aren’t to blame).

Over the next century or two, societies and ecosystems will experience the consequences of this climate change. But our emissions will have even more lasting geologic impacts: According to some studies, greenhouse gas levels may have already warmed the planet enough to delay the onset of the next glacial cycle for at least an additional 50,000 years.

The sun is the ultimate source of energy in Earth’s climate system, so it’s a natural candidate for causing climate change. And solar activity has certainly changed over time. We know from satellite measurements and other astronomical observations that the sun’s output changes on 11-year cycles. Geologic records and sunspot numbers, which astronomers have tracked for centuries, also show long-term variations in the sun’s activity, including some exceptionally quiet periods in the late 1600s and early 1800s.

We know that, from 1900 until the 1950s, solar irradiance increased. And studies suggest that this had a modest effect on early 20th century climate, explaining up to 10 percent of the warming that’s occurred since the late 1800s. However, in the second half of the century, when the most warming occurred, solar activity actually declined . This disparity is one of the main reasons we know that the sun is not the driving force behind climate change.

Another reason we know that solar activity hasn’t caused recent warming is that, if it had, all the layers of the atmosphere should be heating up. Instead, data show that the upper atmosphere has actually cooled in recent decades — a hallmark of greenhouse warming .

So how about volcanoes? Eruptions cool the planet by injecting ash and aerosol particles into the atmosphere that reflect sunlight. We’ve observed this effect in the years following large eruptions. There are also some notable historical examples, like when Iceland’s Laki volcano erupted in 1783, causing widespread crop failures in Europe and beyond, and the “ year without a summer ,” which followed the 1815 eruption of Mount Tambora in Indonesia.

Since volcanoes mainly act as climate coolers, they can’t really explain recent warming. However, scientists say that they may also have contributed slightly to rising temperatures in the early 20th century. That’s because there were several large eruptions in the late 1800s that cooled the planet, followed by a few decades with no major volcanic events when warming caught up. During the second half of the 20th century, though, several big eruptions occurred as the planet was heating up fast. If anything, they temporarily masked some amount of human-caused warming.

The second way volcanoes can impact climate is by emitting carbon dioxide. This is important on time scales of millions of years — it’s what keeps the planet habitable (see Question 5 for more on the greenhouse effect). But by comparison to modern anthropogenic emissions, even big eruptions like Krakatoa and Mount St. Helens are just a drop in the bucket. After all, they last only a few hours or days, while we burn fossil fuels 24-7. Studies suggest that, today, volcanoes account for 1 to 2 percent of total CO2 emissions.

When a big snowstorm hits the United States, climate denialists can try to cite it as proof that climate change isn’t happening. In 2015, Senator James Inhofe, an Oklahoma Republican, famously lobbed a snowball in the Senate as he denounced climate science. But these events don’t actually disprove climate change.

While there have been some memorable storms in recent years, winters are actually warming across the world. In the United States, average temperatures in December, January and February have increased by about 2.5 degrees this century.

On the flip side, record cold days are becoming less common than record warm days. In the United States, record highs now outnumber record lows two-to-one . And ever-smaller areas of the country experience extremely cold winter temperatures . (The same trends are happening globally.)

So what’s with the blizzards? Weather always varies, so it’s no surprise that we still have severe winter storms even as average temperatures rise. However, some studies suggest that climate change may be to blame. One possibility is that rapid Arctic warming has affected atmospheric circulation, including the fast-flowing, high-altitude air that usually swirls over the North Pole (a.k.a. the Polar Vortex ). Some studies suggest that these changes are bringing more frigid temperatures to lower latitudes and causing weather systems to stall , allowing storms to produce more snowfall. This may explain what we’ve experienced in the U.S. over the past few decades, as well as a wintertime cooling trend in Siberia , although exactly how the Arctic affects global weather remains a topic of ongoing scientific debate .

Climate change may also explain the apparent paradox behind some of the other places on Earth that haven’t warmed much. For instance, a splotch of water in the North Atlantic has cooled in recent years, and scientists say they suspect that may be because ocean circulation is slowing as a result of freshwater streaming off a melting Greenland . If this circulation grinds almost to a halt, as it’s done in the geologic past, it would alter weather patterns around the world.

Not all cold weather stems from some counterintuitive consequence of climate change. But it’s a good reminder that Earth’s climate system is complex and chaotic, so the effects of human-caused changes will play out differently in different places. That’s why “global warming” is a bit of an oversimplification. Instead, some scientists have suggested that the phenomenon of human-caused climate change would more aptly be called “ global weirding .”

Extreme weather and natural disasters are part of life on Earth — just ask the dinosaurs. But there is good evidence that climate change has increased the frequency and severity of certain phenomena like heat waves, droughts and floods. Recent research has also allowed scientists to identify the influence of climate change on specific events.

Let’s start with heat waves . Studies show that stretches of abnormally high temperatures now happen about five times more often than they would without climate change, and they last longer, too. Climate models project that, by the 2040s, heat waves will be about 12 times more frequent. And that’s concerning since extreme heat often causes increased hospitalizations and deaths, particularly among older people and those with underlying health conditions. In the summer of 2003, for example, a heat wave caused an estimated 70,000 excess deaths across Europe. (Human-caused warming amplified the death toll .)

Climate change has also exacerbated droughts , primarily by increasing evaporation. Droughts occur naturally because of random climate variability and factors like whether El Niño or La Niña conditions prevail in the tropical Pacific. But some researchers have found evidence that greenhouse warming has been affecting droughts since even before the Dust Bowl . And it continues to do so today. According to one analysis , the drought that afflicted the American Southwest from 2000 to 2018 was almost 50 percent more severe because of climate change. It was the worst drought the region had experienced in more than 1,000 years.

Rising temperatures have also increased the intensity of heavy precipitation events and the flooding that often follows. For example, studies have found that, because warmer air holds more moisture, Hurricane Harvey, which struck Houston in 2017, dropped between 15 and 40 percent more rainfall than it would have without climate change.

It’s still unclear whether climate change is changing the overall frequency of hurricanes, but it is making them stronger . And warming appears to favor certain kinds of weather patterns, like the “ Midwest Water Hose ” events that caused devastating flooding across the Midwest in 2019 .

It’s important to remember that in most natural disasters, there are multiple factors at play. For instance, the 2019 Midwest floods occurred after a recent cold snap had frozen the ground solid, preventing the soil from absorbing rainwater and increasing runoff into the Missouri and Mississippi Rivers. These waterways have also been reshaped by levees and other forms of river engineering, some of which failed in the floods.

Wildfires are another phenomenon with multiple causes. In many places, fire risk has increased because humans have aggressively fought natural fires and prevented Indigenous peoples from carrying out traditional burning practices. This has allowed fuel to accumulate that makes current fires worse .

However, climate change still plays a major role by heating and drying forests, turning them into tinderboxes. Studies show that warming is the driving factor behind the recent increases in wildfires; one analysis found that climate change is responsible for doubling the area burned across the American West between 1984 and 2015. And researchers say that warming will only make fires bigger and more dangerous in the future.

It depends on how aggressively we act to address climate change. If we continue with business as usual, by the end of the century, it will be too hot to go outside during heat waves in the Middle East and South Asia . Droughts will grip Central America, the Mediterranean and southern Africa. And many island nations and low-lying areas, from Texas to Bangladesh, will be overtaken by rising seas. Conversely, climate change could bring welcome warming and extended growing seasons to the upper Midwest , Canada, the Nordic countries and Russia . Farther north, however, the loss of snow, ice and permafrost will upend the traditions of Indigenous peoples and threaten infrastructure.

It’s complicated, but the underlying message is simple: unchecked climate change will likely exacerbate existing inequalities . At a national level, poorer countries will be hit hardest, even though they have historically emitted only a fraction of the greenhouse gases that cause warming. That’s because many less developed countries tend to be in tropical regions where additional warming will make the climate increasingly intolerable for humans and crops. These nations also often have greater vulnerabilities, like large coastal populations and people living in improvised housing that is easily damaged in storms. And they have fewer resources to adapt, which will require expensive measures like redesigning cities, engineering coastlines and changing how people grow food.

Already, between 1961 and 2000, climate change appears to have harmed the economies of the poorest countries while boosting the fortunes of the wealthiest nations that have done the most to cause the problem, making the global wealth gap 25 percent bigger than it would otherwise have been. Similarly, the Global Climate Risk Index found that lower income countries — like Myanmar, Haiti and Nepal — rank high on the list of nations most affected by extreme weather between 1999 and 2018. Climate change has also contributed to increased human migration, which is expected to increase significantly .

Even within wealthy countries, the poor and marginalized will suffer the most. People with more resources have greater buffers, like air-conditioners to keep their houses cool during dangerous heat waves, and the means to pay the resulting energy bills. They also have an easier time evacuating their homes before disasters, and recovering afterward. Lower income people have fewer of these advantages, and they are also more likely to live in hotter neighborhoods and work outdoors, where they face the brunt of climate change.

These inequalities will play out on an individual, community, and regional level. A 2017 analysis of the U.S. found that, under business as usual, the poorest one-third of counties, which are concentrated in the South, will experience damages totaling as much as 20 percent of gross domestic product, while others, mostly in the northern part of the country, will see modest economic gains. Solomon Hsiang, an economist at University of California, Berkeley, and the lead author of the study, has said that climate change “may result in the largest transfer of wealth from the poor to the rich in the country’s history.”

Even the climate “winners” will not be immune from all climate impacts, though. Desirable locations will face an influx of migrants. And as the coronavirus pandemic has demonstrated, disasters in one place quickly ripple across our globalized economy. For instance, scientists expect climate change to increase the odds of multiple crop failures occurring at the same time in different places, throwing the world into a food crisis .

On top of that, warmer weather is aiding the spread of infectious diseases and the vectors that transmit them, like ticks and mosquitoes . Research has also identified troubling correlations between rising temperatures and increased interpersonal violence , and climate change is widely recognized as a “threat multiplier” that increases the odds of larger conflicts within and between countries. In other words, climate change will bring many changes that no amount of money can stop. What could help is taking action to limit warming.

One of the most common arguments against taking aggressive action to combat climate change is that doing so will kill jobs and cripple the economy. But this implies that there’s an alternative in which we pay nothing for climate change. And unfortunately, there isn’t. In reality, not tackling climate change will cost a lot , and cause enormous human suffering and ecological damage, while transitioning to a greener economy would benefit many people and ecosystems around the world.

Let’s start with how much it will cost to address climate change. To keep warming well below 2 degrees Celsius, the goal of the Paris Climate Agreement, society will have to reach net zero greenhouse gas emissions by the middle of this century. That will require significant investments in things like renewable energy, electric cars and charging infrastructure, not to mention efforts to adapt to hotter temperatures, rising sea-levels and other unavoidable effects of current climate changes. And we’ll have to make changes fast.

Estimates of the cost vary widely. One recent study found that keeping warming to 2 degrees Celsius would require a total investment of between $4 trillion and $60 trillion, with a median estimate of $16 trillion, while keeping warming to 1.5 degrees Celsius could cost between $10 trillion and $100 trillion, with a median estimate of $30 trillion. (For reference, the entire world economy was about $88 trillion in 2019.) Other studies have found that reaching net zero will require annual investments ranging from less than 1.5 percent of global gross domestic product to as much as 4 percent . That’s a lot, but within the range of historical energy investments in countries like the U.S.

Now, let’s consider the costs of unchecked climate change, which will fall hardest on the most vulnerable. These include damage to property and infrastructure from sea-level rise and extreme weather, death and sickness linked to natural disasters, pollution and infectious disease, reduced agricultural yields and lost labor productivity because of rising temperatures, decreased water availability and increased energy costs, and species extinction and habitat destruction. Dr. Hsiang, the U.C. Berkeley economist, describes it as “death by a thousand cuts.”

As a result, climate damages are hard to quantify. Moody’s Analytics estimates that even 2 degrees Celsius of warming will cost the world $69 trillion by 2100, and economists expect the toll to keep rising with the temperature. In a recent survey , economists estimated the cost would equal 5 percent of global G.D.P. at 3 degrees Celsius of warming (our trajectory under current policies) and 10 percent for 5 degrees Celsius. Other research indicates that, if current warming trends continue, global G.D.P. per capita will decrease between 7 percent and 23 percent by the end of the century — an economic blow equivalent to multiple coronavirus pandemics every year. And some fear these are vast underestimates .

Already, studies suggest that climate change has slashed incomes in the poorest countries by as much as 30 percent and reduced global agricultural productivity by 21 percent since 1961. Extreme weather events have also racked up a large bill. In 2020, in the United States alone, climate-related disasters like hurricanes, droughts, and wildfires caused nearly $100 billion in damages to businesses, property and infrastructure, compared to an average of $18 billion per year in the 1980s.

Given the steep price of inaction, many economists say that addressing climate change is a better deal . It’s like that old saying: an ounce of prevention is worth a pound of cure. In this case, limiting warming will greatly reduce future damage and inequality caused by climate change. It will also produce so-called co-benefits, like saving one million lives every year by reducing air pollution, and millions more from eating healthier, climate-friendly diets. Some studies even find that meeting the Paris Agreement goals could create jobs and increase global G.D.P . And, of course, reining in climate change will spare many species and ecosystems upon which humans depend — and which many people believe to have their own innate value.

The challenge is that we need to reduce emissions now to avoid damages later, which requires big investments over the next few decades. And the longer we delay, the more we will pay to meet the Paris goals. One recent analysis found that reaching net-zero by 2050 would cost the U.S. almost twice as much if we waited until 2030 instead of acting now. But even if we miss the Paris target, the economics still make a strong case for climate action, because every additional degree of warming will cost us more — in dollars, and in lives.

Veronica Penney contributed reporting.

Illustration photographs by Esther Horvath, Max Whittaker, David Maurice Smith and Talia Herman for The New York Times; Esther Horvath/Alfred-Wegener-Institut

An earlier version of this article misidentified the authors of The Debunking Handbook. It was written by social scientists who study climate communication, not a team of climate scientists.

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5 things you should know about the greenhouse gases warming the planet

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News stories about the climate crisis often contain mentions of greenhouse gases, and the greenhouse effect. Whilst most will find the analogy easy to understand, what exactly are these gases, and why are they contributing to the warming of the Earth?

1. What is the greenhouse effect?

In a greenhouse, sunlight enters, and heat is retained. The greenhouse effect describes a similar phenomenon on a planetary scale but, instead of the glass of a greenhouse,  certain gases are increasingly raising global temperatures.

The surface of the Earth absorbs just under half of the sun’s energy, while the atmosphere absorbs 23 per cent, and the rest is reflected back into space. Natural processes ensure that the amount of incoming and outgoing energy is equal, keeping the planet’s temperature stable.

However, human activity is resulting in the increased emission of so-called greenhouse gases (GHGs) which, unlike other atmospheric gases such as oxygen and nitrogen, becomes trapped in the atmosphere, unable to escape the planet. This energy returns to the surface, where it is reabsorbed.

Because more energy enters than exits the planet, surface temperatures increase until a new balance is achieved. 

2. Why does the warming matter?

This temperature increase has long-term, adverse effects on the climate, and affects a myriad of natural systems. Effects include increases in the frequency and intensity of extreme weather events – including flooding, droughts, wildfires and hurricanes – that affect millions of people and cause trillions in economic losses.

“Human-caused greenhouse gas emissions endanger human and environmental health,” says Mark Radka, Chief of the UN Environment Programme’s ( UNEP ) Energy and Climate Branch. “And the impacts will become more widespread and severe without strong climate action.”

GHG emissions are critical to understanding and addressing the climate crisis: despite an initial dip due to COVID-19 , the latest UNEP Emissions Gap Report shows a rebound, and forecasts a disastrous global temperature rise of at least 2.7 degrees this century, unless countries make much greater efforts to reduce emissions.

The report found that GHG emissions need to be halved by 2030, if we are to limit global warming to 1.5°C compared to pre-industrial levels by the end of the century.

3. What are the major greenhouse gases?

Water vapour is the biggest overall contributor to the greenhouse effect. However, almost all the water vapour in the atmosphere comes from natural processes.

Carbon dioxide (CO2), methane and nitrous oxide are the major GHGs to worry about. CO2 stays in the atmosphere for up to 1,000 years, methane for around a decade, and nitrous oxide for approximately 120 years.

Measured over a 20-year period, methane is 80 times more potent than CO2 in causing global warming, while nitrous oxide is 280 times more potent.

4. How is human activity producing these greenhouse gases?

Coal, oil, and natural gas continue to power many parts of the world. Carbon is the main element in these fuels and, when they’re burned to generate electricity, power transportation, or provide heat, they produce CO2.

Oil and gas extraction, coal mining, and waste landfills account for 55 per cent of human-caused methane emissions. Approximately 32 per cent of human-caused methane emissions are attributable to cows, sheep and other ruminants that ferment food in their stomachs. Manure decomposition is another agricultural source of the gas, as is rice cultivation. 

Human-caused nitrous oxide emissions largely arise from agriculture practices. Bacteria in soil and water naturally convert nitrogen into nitrous oxide, but fertilizer use and run-off add to this process by putting more nitrogen into the environment.

Fluorinated gases – such as hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride – are GHGs that do not occur naturally. Hydrofluorocarbons are refrigerants used as alternatives to chlorofluorocarbons (CFCs), which, having depleted the ozone layer,were phased out thanks to the Montreal Protocol. The others have industrial and commercial uses.

While fluorinated gases are far less prevalent than other GHGs and do not deplete the ozone layer like CFCs, they are still very powerful. Over a 20-year period, the global warming potential of some fluorinated gases is up to 16,300 times greater than that of CO2.

5. What can we do to reduce GHG emissions?

Shifting to renewable energy, putting a price on carbon, and phasing out coal are all important elements in reducing GHG emissions. Ultimately, stronger emission-reduction targets are necessary for the preservation of long-term human and environmental health.

“We need to implement strong policies that back the raised ambitions,” says Mr. Radka. “We cannot continue down the same path and expect better results. Action is needed now.”

During COP26, the European Union and the United States launched the Global Methane Pledge, which will see over 100 countries aim to reduce 30 per cent of methane emissions in the fuel, agriculture and waste sectors by 2030.

Despite the challenges, there is reason to be positive. From 2010 to 2021, policies were put in place  to lower annual emissions by 11 gigatons by 2030 compared to what would have otherwise happened. Individuals can also join the UN’s #ActNow campaign for ideas to take climate-positive actions.

By making choices that have less harmful effects on the environment, everyone can be a part of the solution and influence change. Speaking up is one way to multiply impact and create change on a much bigger scale.  

UNEP’s role in reducing GHGs

• UNEP has outlined its six-sector solution, which can reduce 29–32 gigatons of carbon dioxide by 2030 to meet the 1.5°C warming limit. The six sectors identified are: energy; industry; agricultureand food; forests andland use; transport; and buildings and cities.
• UNEP also maintains an online “Climate Note,” a tool that visualizes the changing state of the climate with a baseline of 1990.
• Through its other multilateral environmental agreements and reports, UNEP raises awareness and advocates for effective environmental action. UNEP will continue to work closely with its 193 Member States and other stakeholders to set the environmental agenda and advocate for a drastic reduction in GHG emissions.
• greenhouse gas emissions

Climate Change: Evidence and Causes: Update 2020 (2020)

Chapter: conclusion, c onclusion.

This document explains that there are well-understood physical mechanisms by which changes in the amounts of greenhouse gases cause climate changes. It discusses the evidence that the concentrations of these gases in the atmosphere have increased and are still increasing rapidly, that climate change is occurring, and that most of the recent change is almost certainly due to emissions of greenhouse gases caused by human activities. Further climate change is inevitable; if emissions of greenhouse gases continue unabated, future changes will substantially exceed those that have occurred so far. There remains a range of estimates of the magnitude and regional expression of future change, but increases in the extremes of climate that can adversely affect natural ecosystems and human activities and infrastructure are expected.

Citizens and governments can choose among several options (or a mixture of those options) in response to this information: they can change their pattern of energy production and usage in order to limit emissions of greenhouse gases and hence the magnitude of climate changes; they can wait for changes to occur and accept the losses, damage, and suffering that arise; they can adapt to actual and expected changes as much as possible; or they can seek as yet unproven “geoengineering” solutions to counteract some of the climate changes that would otherwise occur. Each of these options has risks, attractions and costs, and what is actually done may be a mixture of these different options. Different nations and communities will vary in their vulnerability and their capacity to adapt. There is an important debate to be had about choices among these options, to decide what is best for each group or nation, and most importantly for the global population as a whole. The options have to be discussed at a global scale because in many cases those communities that are most vulnerable control few of the emissions, either past or future. Our description of the science of climate change, with both its facts and its uncertainties, is offered as a basis to inform that policy debate.

A CKNOWLEDGEMENTS

The following individuals served as the primary writing team for the 2014 and 2020 editions of this document:

• Eric Wolff FRS, (UK lead), University of Cambridge
• Inez Fung (NAS, US lead), University of California, Berkeley
• Brian Hoskins FRS, Grantham Institute for Climate Change
• John F.B. Mitchell FRS, UK Met Office
• Tim Palmer FRS, University of Oxford
• Benjamin Santer (NAS), Lawrence Livermore National Laboratory
• John Shepherd FRS, University of Southampton
• Keith Shine FRS, University of Reading.
• Susan Solomon (NAS), Massachusetts Institute of Technology
• Kevin Trenberth, National Center for Atmospheric Research
• John Walsh, University of Alaska, Fairbanks
• Don Wuebbles, University of Illinois

Staff support for the 2020 revision was provided by Richard Walker, Amanda Purcell, Nancy Huddleston, and Michael Hudson. We offer special thanks to Rebecca Lindsey and NOAA Climate.gov for providing data and figure updates.

The following individuals served as reviewers of the 2014 document in accordance with procedures approved by the Royal Society and the National Academy of Sciences:

• Richard Alley (NAS), Department of Geosciences, Pennsylvania State University
• Alec Broers FRS, Former President of the Royal Academy of Engineering
• Harry Elderfield FRS, Department of Earth Sciences, University of Cambridge
• Joanna Haigh FRS, Professor of Atmospheric Physics, Imperial College London
• Isaac Held (NAS), NOAA Geophysical Fluid Dynamics Laboratory
• John Kutzbach (NAS), Center for Climatic Research, University of Wisconsin
• Jerry Meehl, Senior Scientist, National Center for Atmospheric Research
• John Pendry FRS, Imperial College London
• John Pyle FRS, Department of Chemistry, University of Cambridge
• Gavin Schmidt, NASA Goddard Space Flight Center
• Emily Shuckburgh, British Antarctic Survey
• Gabrielle Walker, Journalist
• Andrew Watson FRS, University of East Anglia

The Support for the 2014 Edition was provided by NAS Endowment Funds. We offer sincere thanks to the Ralph J. and Carol M. Cicerone Endowment for NAS Missions for supporting the production of this 2020 Edition.

F OR FURTHER READING

For more detailed discussion of the topics addressed in this document (including references to the underlying original research), see:

• Intergovernmental Panel on Climate Change (IPCC), 2019: Special Report on the Ocean and Cryosphere in a Changing Climate [ https://www.ipcc.ch/srocc ]
• National Academies of Sciences, Engineering, and Medicine (NASEM), 2019: Negative Emissions Technologies and Reliable Sequestration: A Research Agenda [ https://www.nap.edu/catalog/25259 ]
• Royal Society, 2018: Greenhouse gas removal [ https://raeng.org.uk/greenhousegasremoval ]
• U.S. Global Change Research Program (USGCRP), 2018: Fourth National Climate Assessment Volume II: Impacts, Risks, and Adaptation in the United States [ https://nca2018.globalchange.gov ]
• IPCC, 2018: Global Warming of 1.5°C [ https://www.ipcc.ch/sr15 ]
• USGCRP, 2017: Fourth National Climate Assessment Volume I: Climate Science Special Reports [ https://science2017.globalchange.gov ]
• NASEM, 2016: Attribution of Extreme Weather Events in the Context of Climate Change [ https://www.nap.edu/catalog/21852 ]
• IPCC, 2013: Fifth Assessment Report (AR5) Working Group 1. Climate Change 2013: The Physical Science Basis [ https://www.ipcc.ch/report/ar5/wg1 ]
• NRC, 2013: Abrupt Impacts of Climate Change: Anticipating Surprises [ https://www.nap.edu/catalog/18373 ]
• NRC, 2011: Climate Stabilization Targets: Emissions, Concentrations, and Impacts Over Decades to Millennia [ https://www.nap.edu/catalog/12877 ]
• Royal Society 2010: Climate Change: A Summary of the Science [ https://royalsociety.org/topics-policy/publications/2010/climate-change-summary-science ]
• NRC, 2010: America’s Climate Choices: Advancing the Science of Climate Change [ https://www.nap.edu/catalog/12782 ]

Much of the original data underlying the scientific findings discussed here are available at:

• https://data.ucar.edu/
• https://climatedataguide.ucar.edu
• https://iridl.ldeo.columbia.edu
• https://ess-dive.lbl.gov/
• https://www.ncdc.noaa.gov/
• https://www.esrl.noaa.gov/gmd/ccgg/trends/
• http://scrippsco2.ucsd.edu
• http://hahana.soest.hawaii.edu/hot/

Climate change is one of the defining issues of our time. It is now more certain than ever, based on many lines of evidence, that humans are changing Earth's climate. The Royal Society and the US National Academy of Sciences, with their similar missions to promote the use of science to benefit society and to inform critical policy debates, produced the original Climate Change: Evidence and Causes in 2014. It was written and reviewed by a UK-US team of leading climate scientists. This new edition, prepared by the same author team, has been updated with the most recent climate data and scientific analyses, all of which reinforce our understanding of human-caused climate change.

Scientific information is a vital component for society to make informed decisions about how to reduce the magnitude of climate change and how to adapt to its impacts. This booklet serves as a key reference document for decision makers, policy makers, educators, and others seeking authoritative answers about the current state of climate-change science.

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ECONLIB CEE

Greenhouse Effect

By thomas schelling.

By Thomas Schelling,

What Is It?

The “greenhouse effect” is a complicated process by which the earth is becoming progressively warmer. The earth is bathed in sunlight, some of it reflected back into space and some absorbed. If the absorption is not matched by radiation back into space, the earth will get warmer until the intensity of that radiation matches the incoming sunlight. Some atmospheric gases absorb outward infrared radiation, warming the atmosphere. Carbon dioxide is one of these gases; so are methane, nitrous oxide, and the chlorofluorocarbons (CFCs). The concentrations of these gases are increasing, with the result that the earth is absorbing more sunlight and getting warmer.

This greenhouse phenomenon is truly the result of a “global common” (see The Tragedy of the Commons ). Because no one owns the atmosphere, no one has a sufficient incentive to take account of the change to the atmosphere caused by his or her emission of carbon. Also, carbon emitted has the same effect no matter where on earth it happens.

How Serious Is It?

The expected change in global average temperature for a doubling of CO 2 is 1.5 to 4.5 degrees centigrade. But translating a change in temperature into a change in climates is full of uncertainties. Meteorologists predict greater temperature change in the polar regions than near the equator. This change could cause changes in circulation of air and water. The results may be warmer temperatures in some places and colder in others, wetter climates in some places and drier in others.

Temperature is useful as an index of climate change. A band of about one degree covers variations in average temperatures since the last ice age. This means that climates will change more in the next one hundred years than in the last ten thousand. But to put this in perspective, remember that people have been migrating great distances for thousands of years, experiencing changes in climate greater than any being forecast.

The models of global warming project only gradual changes. Climates will “migrate” slowly. The climate of Kansas may become like Oklahoma’s, but not like that of Oregon or Massachusetts. But a caveat is in order: the models probably cannot project discontinuities because nothing goes into them that will produce drastic change. There may be phenomena that could produce drastic changes, but they are not known with enough confidence to introduce into the models.

Carbon dioxide has increased about 25 percent since the onset of the industrial revolution. The global average temperature rose almost half a degree during the first forty years of this century, was level for the next forty, and rose during the eighties. Yet whether or not we are witnessing the greenhouse effect is unknown because other decades-long influences such as changes in solar intensity and in the atmosphere’s particulate matter can obscure any smooth greenhouse trend. In other words, the increase in carbon dioxide will, by itself, cause the greenhouse effect, but other changes in the universe may offset it.

Even if we had confident estimates of climate change for different regions of the world, there would be uncertainties about the kind of world we will have fifty or a hundred years from now. Suppose the kind of climate change expected between now and, say, 2080 had already taken place, since 1900. Ask a seventy-five-year-old farm couple living on the same farm where they were born: would the change in the climate be among the most dramatic changes in either their farming or their lifestyle? The answer most likely would be no. Changes from horses to tractors and from kerosene to electricity would be much more important.

Climate change would have made a vastly greater difference to the way people lived and earned their living in 1900 than today. Today, little of our gross domestic product is produced outdoors, and therefore, little is susceptible to climate. Agriculture and forestry are less than 3 percent of total output, and little else is much affected. Even if agricultural productivity declined by a third over the next half-century, the per capita GNP we might have achieved by 2050 we would still achieve in 2051. Considering that agricultural productivity in most parts of the world continues to improve (and that many crops may benefit directly from enhanced photosynthesis due to increased carbon dioxide), it is not at all certain that the net impact on agriculture will be negative or much noticed in the developed world.

Its Effects on Developing Countries

Climate changes would have greater impact in underdeveloped countries. Agriculture provides the livelihoods of 30 percent or more of the population in much of the developing world. While there is no strong presumption that the climates prevailing in different regions fifty or a hundred years from now will be less conducive to food production, those people are vulnerable in a way that Americans and west Europeans are not. Nor can the impact on their health be dismissed. Parasitic and other vectorborne diseases affecting hundreds of millions of people are sensitive to climate.

Yet the trend in developing countries is to be less dependent on agriculture. If per capita income in such countries grows in the next forty years as rapidly as it has in the forty just past, vulnerability to climate change should diminish. This is pertinent to whether developing countries should make sacrifices to minimize the emission of gases that may change climate to their disadvantage. Their best defense against climate change will be their own continued development.

Population is an important factor. Carbon emissions in developing countries rise with population. For instance, if China holds population growth to near zero for the next couple of generations, it may do as much for the earth’s atmosphere as would a heroic anticarbon program coupled with 2 percent annual population growth. Furthermore, the most likely adverse impact of climate change would be on food production, and in the poorest parts of the world the adequacy of food depends on the number of mouths.

Why Should Developed Countries Do Anything?

Why might developed countries care enough about climate to do anything about it? The answer depends on how much people in developed countries care about people in developing countries and on how expensive it is to do something worthwhile. Abatement programs in a number of econometric models suggest that doing something worthwhile would cost about 2 percent of GNP in perpetuity. Two percent of the U.S. GNP is over $100 billion a year, and that is an annual cost that would continue forever.

One argument for doing something is that the developing countries are vulnerable, and we care about their well-being. But if the developed countries were prepared to invest, say, $200 billion a year in greenhouse gas abatement, explicitly for the benefit of developing countries fifty years or more from now, the developing countries would probably clamor, understandably, to receive the resources immediately in support of their continued development.

A second argument is that our natural environment may be severely damaged. This is the crux of the political debate over the greenhouse effect, but it is an issue that no one really understands. It is difficult to know how to value what is at risk, and difficult even to know just what is at risk. The benefits of slowing climate change by some particular amount are even more uncertain.

A third argument is that the conclusion I reported earlier—that climates will change slowly and not much—may be wrong. The models do not produce surprises. The possibility has to be considered that some atmospheric or oceanic circulatory systems may flip to alternative equilibria, producing regional changes that are sudden and extreme. A currently discussed possibility is in the way oceans behave. If the gulf stream flipped into a new pattern, the climatic consequences might be sudden and severe. (Paradoxically, global warming might severely cool western Europe.)

Is 2 percent of GNP forever, to postpone the doubling of carbon in the atmosphere, a big number or a small one? That depends on what the comparison is. A better question—assuming we were prepared to spend 2 percent of GNP to reduce the damage from climate change—is whether we might find better uses for the money.

I mentioned one such use—directly investing to improve the economies of the poorer countries. Another would be direct investment in preserving species or ecosystems or wilderness areas, if the alternative is to invest trillions in the reduction of carbon emissions.

What Solutions Are Proposed?

What can be done to reduce or offset carbon emissions? Reducing energy use and the carbon content of energy have received most of the attention. There are other possibilities. Trees store carbon. A new forest will absorb carbon until it reaches maturity; it then holds its carbon but does not absorb more. The area available for reforestation throughout the world suggests that reforestation can contribute, but not much.

Stopping or slowing deforestation is important for other reasons but is quantitatively more important than reforestation, partly because forest subsoils typically contain carbon greater than the amount in the trees themselves, and this carbon is subject to oxidation when the trees are removed.

Also, substances or objects can be put in orbit or in the stratosphere to reflect incoming sunlight. Some of these are as apparently innocuous as stimulating cloud formation and some as dramatic as huge mylar balloons in low earth orbit. If in decades to come the greenhouse impact confirms the more alarmist expectations, and if the costs of reducing emissions prove unmanageable, some of these “geoengineering” options will invite attention.

The main responses will be to adapt as the climate changes and to reduce carbon emissions. (CFCs are potent greenhouse gases and, if unchecked, might have rivaled carbon dioxide in decades to come. International actions to reduce or eliminate CFCs are making progress and are among the cheapest ways of reducing greenhouse emissions.)

It is improbable that the developing world, at least for the next several decades, will incur any significant sacrifice in the interest of reduced carbon, nor would it be advisable. Financing energy conservation, energy efficiency, and a switch from high-carbon to lower-carbon or noncarbon fuels in Asia and Africa would not only be a major economic enterprise, but also a complex effort in international diplomacy and politics. If successful, it would increase the costs to the developed world by at least another percent or two on top of the 2 percent I mentioned.

A universal carbon tax is a popular proposal among economists because it promises an efficient solution. A carbon tax set equally for all users worldwide would achieve a given reduction in the use of carbon at the lowest cost. If user A values his use of one ton of carbon at two thousand dollars more than its net-of-tax price, and if the tax is four hundred dollars per ton, he will continue to use the carbon because doing so is worthwhile. If user B values his use of one ton at only three hundred dollars more than the net-of-tax price, the tax will induce him to end his use. Thus the tax would eliminate the lowest-valued uses of carbon and would leave the highest-valued ones in place. A carbon tax would require no negotiation except over a tax rate and a formula for distributing the proceeds. But a tax rate that made a big dent in the greenhouse problem would have to be equivalent to around a dollar per gallon on motor fuel, and for the United States alone such a tax on coal, petroleum, and natural gas would currently yield close to half a trillion dollars per year in revenue, almost 10 percent of our GNP. It is doubtful that any greenhouse taxing agency would be allowed to collect that kind of revenue, or that a treaty requiring the United States to levy internal carbon taxation at that level would be ratified.

Tradable permits have been proposed as an alternative to the tax. The main possibilities are estimating “reasonable” emissions country by country and establishing commensurate quotas, or distributing tradable rights in accordance with some “equitable” criterion. Depending on how restrictive the emission rights might be, the latter amounts to distributing trillions of dollars (in present value terms), an unlikely prospect. If quotas are negotiated to correspond to countries’ currently “reasonable” emissions levels, they will surely be renegotiated every few years, and selling an emissions right will be perceived as evidence that a quota was initially too generous.

A helpful model for conceptualizing a greenhouse regime among the richer countries is the negotiations among the nations of Western Europe for distributing Marshall Plan aid after World War II. There was never a formula or explicit criterion, such as equalizing living standards, maximizing aggregate growth, or establishing a floor under levels of living. Baseline dollar-balance-of-payments deficits were a point of departure, but the negotiations took into account other factors such as investment needs and traditional consumption levels. The United States insisted that the recipients argue out and agree on shares. In the end they did not quite make it, the United States having to make the final allocation. But all the submission of data and open argument led, if not to consensus, to a reasonable appreciation of each nation’s needs. Distribution of Marshall Plan funds is the only model of multilateral negotiation involving resources commensurate with the cost of greenhouse abatement. (In the first year Marshall Plan funds were about 1.5 percent of U.S. GNP and—adjusting for overvalued currencies—probably 5 percent of recipient countries’ GNP.)

What the Marshall Plan model suggests is that the participants in a greenhouse regime would submit for each other’s scrutiny and cross-examination plans for reducing carbon emissions. The plans would be accompanied by estimates of emissions, but any commitments would be to the policies, not the emissions.

The alternative is commitments to specific levels of emissions. Because target dates would be a decade or two in the future, monitoring a country’s progress would be more ambiguous than monitoring the implementation of policies.

______________________________________________________________________________________________________________________________

Thomas C. Schelling is a professor of economics at the University of Maryland School of Public Affairs in College Park. For most of his professional life he was an economics professor at Harvard University. In 1991 he was president of the American Economic Association. He is an elected member of the National Academy of Sciences.

Ausubel, Jesse. “Does Climate Still Matter?” Nature 350, April 25, 1991, 649-52.

Cline, William R. The Greenhouse Effect: Global Economic Consequences. 1992.

Congressional Budget Office. Carbon Charges as a Response to Global Warming: The Effects of Taxing Fossil Fuels. 1990.

Dornbush, Rudiger, and James M. Poterba. Global Warming: Economic Policy Responses. 1991.

Nordhaus, William D. “The Cost of Slowing Climate Change: A Survey.” Energy Journal 12, no. 1 (1991): 37-66.

_______________________________________________________________________________________________________________________________

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Robert Bradley and Richard Fulmer, Those Old Oil Company Ads: Misleading, False, or Simply Reasonable? at Econlib, March 2, 2022.

Bryan Caplan, The Moral Case for Fossil Fuels: We Can Live With Warming , at EconLog, December 12, 2014.

Robert Murphy, The Economics of Climate Change , at Econlib, July 2009.

Pedro Schwartz, Climate Change: A Tragedy of the Commons? at Econlib, March 2020.

Pedro Schwartz, Climate Change: What is (Not) To Be Done , at Econlib, April 2020.

Judith Curry on Climate Change , EconTak podcast, December 23, 2013.

Martin Weitzman on Climate Change , EconTalk podcast, June 1, 2015.

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Data versus drama.

• Biology Article
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Greenhouse Effect

Table of Contents

What is the Greenhouse Effect?

Greenhouse gases, causes of greenhouse effect, effects of greenhouse effect, runaway greenhouse effect, greenhouse effect definition.

“Greenhouse effect is the process by which radiations from the sun are absorbed by the greenhouse gases and not reflected back into space. This insulates the surface of the earth and prevents it from freezing.”

A greenhouse is a house made of glass that can be used to grow plants. The sun’s radiations warm the plants and the air inside the greenhouse. The heat trapped inside can’t escape out and warms the greenhouse which is essential for the growth of the plants. Same is the case in the earth’s atmosphere.

During the day the sun heats up the earth’s atmosphere. At night, when the earth cools down the heat is radiated back into the atmosphere. During this process, the heat is absorbed by the greenhouse gases in the earth’s atmosphere. This is what makes the surface of the earth warmer, that makes the survival of living beings on earth possible.

However, due to the increased levels of greenhouse gases, the temperature of the earth has increased considerably. This has led to several drastic effects.

Let us have a look at the greenhouse gases and understand the causes and consequences of greenhouse effects with the help of a diagram.

Also Read:  Global Warming

“Greenhouse gases are the gases that absorb the infrared radiations and create a greenhouse effect. For eg., carbondioxide and chlorofluorocarbons.” Greenhouse Effect Diagram

The Diagram shows Greenhouse Gases such as carbon dioxide are the primary cause for the Greenhouse Effect

The major contributors to the greenhouse gases are factories, automobiles, deforestation , etc. The increased number of factories and automobiles increases the amount of these gases in the atmosphere. The greenhouse gases never let the radiations escape from the earth and increase the surface temperature of the earth. This then leads to global warming.

Also Read:  Our Environment

The major causes of the greenhouse effect are:

Burning of Fossil Fuels

Fossil fuels are an important part of our lives. They are widely used in transportation and to produce electricity. Burning of fossil fuels releases carbon dioxide. With the increase in population, the utilization of fossil fuels has increased. This has led to an increase in the release of greenhouse gases in the atmosphere.

Deforestation

Plants and trees take in carbon dioxide and release oxygen. Due to the cutting of trees, there is a considerable increase in the greenhouse gases which increases the earth’s temperature.

Nitrous oxide used in fertilizers is one of the contributors to the greenhouse effect in the atmosphere.

Industrial Waste and Landfills

The industries and factories produce harmful gases which are released in the atmosphere.

Landfills also release carbon dioxide and methane that adds to the greenhouse gases.

The main effects of increased greenhouse gases are:

Global Warming

It is the phenomenon of a gradual increase in the average temperature of the Earth’s atmosphere. The main cause for this environmental issue is the increased volumes of greenhouse gases such as carbon dioxide and methane released by the burning of fossil fuels, emissions from the vehicles, industries and other human activities.

Depletion of  Ozone Layer

Ozone Layer protects the earth from harmful ultraviolet rays from the sun. It is found in the upper regions of the stratosphere. The depletion of the ozone layer results in the entry of the harmful UV rays to the earth’s surface that might lead to skin cancer and can also change the climate drastically.

The major cause of this phenomenon is the accumulation of natural greenhouse gases including chlorofluorocarbons, carbon dioxide, methane, etc.

Smog and Air Pollution

Smog is formed by the combination of smoke and fog. It can be caused both by natural means and man-made activities.

In general, smog is generally formed by the accumulation of more greenhouse gases including nitrogen and sulfur oxides. The major contributors to the formation of smog are automobile and industrial emissions, agricultural fires, natural forest fires and the reaction of these chemicals among themselves.

Acidification of Water Bodies

Increase in the total amount of greenhouse gases in the air has turned most of the world’s water bodies acidic. The greenhouse gases mix with the rainwater and fall as acid rain. This leads to the acidification of water bodies.

Also, the rainwater carries the contaminants along with it and falls into the river, streams and lakes thereby causing their acidification.

This phenomenon occurs when the planet absorbs more radiation than it can radiate back. Thus, the heat lost from the earth’s surface is less and the temperature of the planet keeps rising. Scientists believe that this phenomenon took place on the surface of Venus billions of years ago.

This phenomenon is believed to have occurred in the following manner:

• A runaway greenhouse effect arises when the temperature of a planet rises to a level of the boiling point of water. As a result, all the water from the oceans converts into water vapour, which traps more heat coming from the sun and further increases the planet’s temperature. This eventually accelerates the greenhouse effect. This is also called the “positive feedback loop”.
• There is another scenario giving way to the runaway greenhouse effect. Suppose the temperature rise due to the above causes reaches such a high level that the chemical reactions begin to occur. These chemical reactions drive carbon dioxide from the rocks into the atmosphere. This would heat the surface of the planet which would further accelerate the transfer of carbon dioxide from the rocks to the atmosphere, giving rise to the runaway greenhouse effect.

In simple words, increasing the greenhouse effect gives rise to a runaway greenhouse effect which would increase the temperature of the earth to such an extent that no life will exist in the near future.

Also Read:  Environmental Issues

To learn more about what is the greenhouse effect, its definition, causes and effects, keep visiting BYJU’S website or download the BYJU’S app for further reference.

Frequently Asked Questions

What is global warming.

The gradual increase in temperature due to the greenhouse effect caused by pollutants, CFCs and carbon dioxide is called global warming. This phenomenon has disturbed the climatic pattern of the earth.

List gases which are responsible for the greenhouse effect.

The major greenhouse gases are: 1) Carbon dioxide 2) Methane 3) Water 4) Nitrous oxide 5) Ozone 6) Chlorofluorocarbons (CFCs)

What is the greenhouse effect?

What are the major causes of the greenhouse effect.

Burning of fossil fuels, deforestation, farming and livestock production all contribute to the greenhouse effect. Industries and factories also play a major role in the release of greenhouse gases.

What would have happened if the greenhouse gases were totally missing in the earth’s atmosphere?

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

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What causes the greenhouse effect? | 16-18 years

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Reinforce your students’ understanding of the cause of the greenhouse effect using this lesson plan with a demonstration and activities for 16–18 year olds

In this activity, students check and clarify their understanding of the greenhouse effect by drawing and comparing diagrams. After observing a teacher demonstration, students work independently and then in collaboration with a partner to share and evaluate their ideas and agree a joint view. They then compare their view with the ideas of other pairs of students.

This activity is best used to consolidate and to check on learning after students have spent some time on this topic.

Learning objectives

Students will:

• Understand the cause of the greenhouse effect.

Sequence of activities

Demonstration.

• Begin with the greenhouse effect demonstration (from T. Lister’s  Classic chemistry demonstrations , number 68), emphasising the observed temperature changes but without providing an explanation at this stage.
• Invite students to say what phenomenon is illustrated by the demonstration and then share the learning objective with them.

Activity: stage 1

• Hand out a copy of the ’Student sheet’ to each student.
• Ask them to draw, by themselves, an annotated diagram to explain the greenhouse effect.

Activity: stage 2

Divide students into pairs. Ask them to

• Compare their diagrams.
• Justify their ideas, where there are differences.
• Agree a common diagram which they draw on an OHT or produce a PowerPoint slide.
• One group to show and explain their diagram to the class using an OHP or a data projector.
• Other groups to add to it (from their own diagram) until all key points have been described.
• Remind students of the demonstration used to start the session.
• Question them on what the lamp and lead foil represented (Sun and Earth).
• Ensure that students modify their original diagram, where necessary, to take account of what other students have said during the session.

Take in the student diagrams and write comments which reinforce the good features. Identify any points that still need developing and indicate where additional support can be found.

The demonstration is a key part of the session and a key to its objective.

The process of comparing diagrams draws students into assessing themselves and their fellow students. It encourages them to listen to the ideas of others.

In the plenary, the students experience a wider range of ideas. They then reassess the completeness of their original diagram.

Even though this may be a final session on this topic, written feedback remains important. It confirms achievement or guides students on how to clarify their understanding.

Practical notes

Health, safety and technical notes.

• See the  greenhouse effect demonstration  for full kit list, safety instructions and procedure for the teacher demonstration.
• Read our standard health and safety guidance .
• Wear eye protection.
• It is the responsibility of the teacher to carry out an appropriate risk assessment.

Expected explanation of the greenhouse effect

• Visible radiation is emitted from the hot sun.
• Some of this radiation is absorbed by the Earth which is consequently warmed.
• Warm earth emits infrared radiation.
• Some of the radiation is absorbed by greenhouse gases such as carbon dioxide. Carbon-oxygen bonds in carbon dioxide molecules vibrate more vigorously.
• Molecules excited in this way collide with other molecules in the atmosphere and spread absorbed energy around.
• The atmosphere becomes warmer.

What causes the greenhouse effect? student sheet

Additional information.

This lesson plan was originally part of the  Assessment for Learning  website, published in 2008.

Assessment for Learning is an effective way of actively involving students in their learning.  Each session plan comes with suggestions about how to organise activities and worksheets that may be used with students.

Acknowledgement

T. Lister,  Classic chemistry demonstrations . London: Royal Society of Chemistry, 1995.

• 16-18 years
• Demonstrations
• Formative assessment 
• Higher-order thinking and metacognition
• Environmental science
• Society and ethics
• Climate change

Specification

• Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life. Water vapour, carbon dioxide and methane are greenhouse gases.
• Students should be able to describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter.
• Describe the greenhouse effect in terms of the interaction of radiation with matter.
• 8.24 Describe how various gases in the atmosphere, including carbon dioxide, methane and water vapour, absorb heat radiated from the Earth, subsequently releasing energy which keeps the Earth warm: this is known as the greenhouse effect
• C1.3.1 describe the greenhouse effect in terms of the interaction of radiation with matter
• C6.2c describe the greenhouse effect in terms of the interaction of radiation with matter within the atmosphere
• C6.3c describe the greenhouse effect in terms of the interaction of radiation with matter within the atmosphere
• Hydrocarbons and alcohols burn in a plentiful supply of oxygen to produce carbon dioxide and water.
• (g) the environmental effects and consequences of the emission of carbon dioxide and sulfur dioxide into the atmosphere through the combustion of fossil fuels
• 2.5.28 demonstrate knowledge that the combustion of fuels is a major source of atmospheric pollution due to: combustion of hydrocarbons producing carbon dioxide, which leads to the greenhouse effect causing sea level rises, flooding and climate change;…
• 2.5.26 demonstrate knowledge that the combustion of fuels is a major source of atmospheric pollution due to: combustion of hydrocarbons producing carbon dioxide, which leads to the greenhouse effect causing sea level rises, flooding and climate change…
• Methane as a contributor to the greenhouse effect.
• The greenhouse effect and the influence of human activity on it.
• Greenhouse gases and their relative effects [especially carbon dioxide and water vapour; also methane, chlorofluorocarbons (CFCs)].
• Possible implications of increased greenhouse effect.

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Greenhouse gases and climate change

Part of Biology Humans and the environment

• An increase in greenhouse gases in the atmosphere is causing the planet to increase in temperature. This is causing climate change.
• The effects of climate change include rising sea levels, more extreme weather and more forest fires.

Video - Greenhouse gases and climate change

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Video transcript video transcript.

Greenhouses can be good for growing plants. But when applied to the whole planet, the greenhouse effect is bad news.

We call the compounds in the atmosphere that trap Earth’s heat, such as carbon dioxide and methane, greenhouse gases. They occur naturally, but human activity has generated more and more greenhouse gases… and they now trap too much heat, raising the Earth’s temperature and causing climate change.

Rising temperatures are melting glaciers, raising sea levels and increasing the risk of flooding worldwide. Climate change disrupts weather patterns, causing events like droughts and wildfires, hurricanes and tornadoes, and extreme cold snaps to become more frequent and severe.

Climate change is also affecting natural habitats so wildlife lose their homes and species die out. The cascading effects across global ecosystems have consequences for all natural life. And that includes us.

To reverse the effects of climate change, both individuals and companies must take action to reduce the amount of greenhouse gas they produce and become more responsible for their impact on the environment.

Can you answer these questions based on the video?

1. Name two greenhouse gases.

2. What are rising temperatures doing?

Show more Show less

Carbon dioxide and methane.

Melting glaciers, raising sea levels and increasing the risk of flooding worldwide.

The greenhouse effect

Thermal energy (heat energy) radiates from the Sun. Some of this hits the Earth. Without this, there would be little or no life on Earth. Not all of the thermal energy that hits the Earth stays here. Some of it is reflected off pale, shiny surfaces like ice and escapes into space.

Some gases in the atmosphere, called greenhouse gases close greenhouse gas Gases such as water vapour, carbon dioxide, and methane in the Earth’s atmosphere that trap heat. , trap escaping thermal energy. This causes some of the thermal energy to return to the surface and warm it up. This is called the greenhouse effect. close greenhouse effect The trapping of the sun's energy due to gases in the Earth's atmosphere. It is much hotter standing in a greenhouse or sitting in a car with the windows up on a sunny day than a cloudy one for the same reason. As there are more greenhouse gases in the atmosphere, the Earth is getting hotter.

Increasing carbon dioxide levels

Humans burn fossil fuels close fossil fuels Coal, oil and natural gas. to generate electricity, to keep buildings warm, and to power cars and other machines. Waste gases are released during this combustion close combustion Another name for burning. When a fuel reacts with oxygen and releases useful energy. , including carbon dioxide. As the human population has increased more fuel is used and more carbon dioxide is released.

Carbon footprint

The impact of climate change

More on Humans and the environment

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People treat the EARTH
 with little respect
 global warming comes to us
 live and direct
 the EARTH is becoming
 a burnt out wreck.
 You see the GREENHOUSE EFFECT
 is in EFFECT. Burning Tropical rain forest
 producing carbon dioxide
 increasing global warming
 sea levels start to rise
 weather patterns are changing
 there’s a lesson to be learnt
 the GREENHOUSE EFFECT is in EFFECT
 we could all get burnt. Greedy developers destroy land
 to build new factories
 killing the indigenous population
 with their economic policies
 animals and plant life become extinct
 along with cures for many diseases
 the chance of breathing fresh clean air
 for ever decreases. The GREE…
 The GREE…
 The GREENHOUSE EFFECT
 Humans treating the EARTH with little respect.
 The GREE…
 The GREE…
 The GREENHOUSE EFFECT
 The EARTH is becoming a nervous wreck. Trees get axed
 to feed the consumer
 atmospheric gases clash
 which equates to danger
 and life on EARTH gets
 stranger
 and now man has his regrets.
 Because
 The GREENHOUSE
 The GREENHOUSE
 The GREENHOUSE EFFECT is in EFFECT

Acknowledgments

Linked articles.

• In this issue Common sense, the least common sense? Carlos Alvarez-Dardet John R Ashton Journal of Epidemiology & Community Health 2005; 59 341-341 Published Online First: 14 Apr 2005.

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