essay of greenhouse gas

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).

Get the huge list of more than 500 Essay Topics and Ideas

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.

Customize your course in 30 seconds

Which class are you in.

Travelling Essay
Picnic Essay
Our Country Essay
My Parents Essay
Essay on Favourite Personality
Essay on Memorable Day of My Life
Essay on Knowledge is Power
Essay on Gurpurab
Essay on My Favourite Season
Essay on Types of Sports

Download the App

ENVIRONMENT

Carbon dioxide levels are at a record high. Here's what you need to know.

Carbon dioxide, a key greenhouse gas that drives global climate change, continues to rise every month. Find out the dangerous role it and other gases play.

By trapping heat from the sun, greenhouse gases have kept Earth's climate habitable for humans and millions of other species. But those gases are now out of balance and threaten to change drastically which living things can survive on this planet—and where.

Atmospheric levels of carbon dioxide—the most dangerous and prevalent greenhouse gas—are at the highest levels ever recorded. Greenhouse gas levels are so high primarily because humans have released them into the air by burning fossil fuels. The gases absorb solar energy and keep heat close to Earth's surface, rather than letting it escape into space. That trapping of heat is known as the greenhouse effect.

The roots of the greenhouse effect concept lie in the 19th century, when French mathematician Joseph Fourier calculated in 1824 that the Earth would be much colder if it had no atmosphere. In 1896, Swedish scientist Svante Arrhenius was the first to link a rise in carbon dioxide gas from burning fossil fuels with a warming effect . Nearly a century later, American climate scientist James E. Hansen testified to Congress that “The greenhouse effect has been detected and is changing our climate now."

Today, climate change is the term scientists use to describe the complex shifts, driven by greenhouse gas concentrations, that are now affecting our planet’s weather and climate systems . Climate change encompasses not only the rising average temperatures we refer to as global warming but also extreme weather events, shifting wildlife populations and and habitats, rising seas , and a range of other impacts.

Governments and organizations around the world such as the Intergovernmental Panel on Climate Change (IPCC), the United Nations body that tracks the latest climate change science, are measuring greenhouse gases, tracking their impacts, and implementing solutions .

Major greenhouse gases and sources

Carbon dioxide (CO 2 ): Carbon dioxide is the primary greenhouse gas, responsible for about three-quarters of emissions . It can linger in the atmosphere for thousands of years . In 2018, carbon dioxide levels reached 411 parts per million at Hawaii's Mauna Loa Atmospheric Baseline Observatory, the highest monthly average ever recorded . Carbon dioxide emissions mainly come from burning organic materials: coal, oil, gas, wood, and solid waste.

FREE BONUS ISSUE

Methane (CH 4 ): The main component of natural gas, methane is released from landfills, natural gas and petroleum industries, and agriculture (especially from the digestive systems of grazing animals). A molecule of methane doesn't stay in the atmosphere as long as a molecule of carbon dioxide—about 12 years—but it is at least 84 times more potent over two decades. It accounts for about 16 percent of all greenhouse gas emissions.

What exactly is lab-grown meat? Here’s what you need to know.

Sea levels are rising at an extraordinary pace. Here's what to know.

Another weapon to fight climate change? Put carbon back where we found it

Nitrous Oxide (N 2 O): Nitrous oxide occupies a relatively small share of global greenhouse gas emissions—about six percent—but it is 264 times more powerful than carbon dioxide over 20 years, and its lifetime in the atmosphere exceeds a century, according to the IPCC. Agriculture and livestock, including fertilizer, manure, and burning of agricultural residues, along with burning fuel, are the biggest sources of nitrous oxide emissions .

Industrial gases: Fluorinated gases such as hydrofluorocarbons, perfluorocarbons, chlorofluorocarbons, sulfur hexafluoride (SF 6 ), and nitrogen trifluoride (NF 3 ) have heat-trapping potential thousands of times greater than CO 2 and stay in the atmosphere for hundreds to thousands of years. Accounting for about 2 percent of all emissions, they're used as refrigerants, solvents, and in manufacturing, sometimes occurring as byproducts.

Other greenhouse gases include water vapor and ozone (O 3 ). Water vapor is actually the world's most abundant greenhouse gas, but it is not tracked the same way as other greenhouse gases because it is not directly emitted by human activity and its effects are not well understood. Similarly, ground-level or tropospheric ozone (not to be confused with the protective stratospheric ozone layer higher up) is not emitted directly but emerges from complex reactions among pollutants in the air.

Effects of greenhouse gases

Greenhouse gases have far-ranging environmental and health effects. They cause climate change by trapping heat, and they also contribute to respiratory disease from smog and air pollution . Extreme weather, food supply disruptions, and increased wildfires are other effects of climate change caused by greenhouse gases. The typical weather patterns we've grown to expect will change ; some species will disappear ; others will migrate or grow . ( Read more about greenhouse gas effects via climate change here . )

How to reduce greenhouse gas emissions

Virtually every sector of the global economy, from manufacturing to agriculture to transportation to power production, contributes greenhouse gases to the atmosphere, so all of them must evolve away from fossil fuels if we are to avoid the worst effects of climate change. Countries around the world acknowledged this reality with the Paris Climate Agreement of 2015. The changes will be most important among the biggest emitters: Twenty countries are responsible for at least three-quarters of the world's greenhouse gas emissions, with China, the United States, and India leading the way .

The technologies for ramping down greenhouse gas emissions already exist, for the most part. They include swapping fossil fuels for renewable sources, boosting energy efficiency, and discouraging carbon emissions by putting a price on them. ( Read more about such solutions here . )

The world technically has only one-fifth of its "carbon budget" —the total is 2.8 trillion metric tons—remaining in order to avoid warming the Earth more than 1.5 degrees Celsius. Halting the trends in motion will require more than just phasing out fossil fuels. In fact, the paths to halting global temperature increases of 1.5 or 2 degrees C, the two goals outlined by the IPCC, rely in some way on adopting methods of sucking CO2 from the sky . Those include planting trees, conserving existing forests and grasslands, and capturing CO 2 from power plants and factories.

How the historic climate bill will dramatically reduce U.S. emissions

Rest in … compost? These ‘green funerals’ offer an eco-friendly afterlife.

‘It’s now or never’: UN climate report’s 4 urgent takeaways

The scientific case against gas stoves

The gas in this exploding mine is odorless, colorless—and could transform the world

Environment
Paid Content

History & Culture

History & Culture
History Magazine
Gory Details
2023 in Review
Mind, Body, Wonder
Terms of Use
Privacy Policy
Your US State Privacy Rights
Children's Online Privacy Policy
Interest-Based Ads
About Nielsen Measurement
Do Not Sell or Share My Personal Information
Nat Geo Home
Attend a Live Event
Book a Trip
Inspire Your Kids
Shop Nat Geo
Visit the D.C. Museum
Learn About Our Impact
Support Our Mission
Advertise With Us
Customer Service
Renew Subscription
Manage Your Subscription
Work at Nat Geo
Sign Up for Our Newsletters
Contribute to Protect the Planet

Greenhouse Effect

Global warming describes the current rise in the average temperature of Earth’s air and oceans. Global warming is often described as the most recent example of climate change.

Earth Science, Meteorology, Geography

Loading ...

Global warming describes the current rise in the average temperature of Earth’s air and oceans. Global warming is often described as the most recent example of climate change . Earth’s climate has changed many times. Our planet has gone through multiple ice ages , in which ice sheets and glaciers covered large portions of Earth. It has also gone through warm periods when temperatures were higher than they are today. Past changes in Earth’s temperature happened very slowly, over hundreds of thousands of years. However, the recent warming trend is happening much faster than it ever has. Natural cycles of warming and cooling are not enough to explain the amount of warming we have experienced in such a short time—only human activities can account for it. Scientists worry that the climate is changing faster than some living things can adapt to it. In 1988, the World Meteorological Organization and the United Nations Environment Programme established a committee of climatologists , meteorologists , geographers , and other scientists from around the world. This Intergovernmental Panel on Climate Change (IPCC) includes thousands of scientists who review the most up-to-date research available related to global warming and climate change. The IPCC evaluates the risk of climate change caused by human activities. According to the IPCC’s most recent report (in 2007), Earth’s average surface temperatures have risen about 0.74 degrees Celsius (1.33 degrees Fahrenheit) during the past 100 years. The increase is greater in northern latitudes . The IPCC also found that land regions are warming faster than oceans. The IPCC states that most of the temperature increase since the mid-20th century is likely due to human activities. The Greenhouse Effect Human activities contribute to global warming by increasing the greenhouse effect. The greenhouse effect happens when certain gases—known as greenhouse gases —collect in Earth’s atmosphere . These gases, which occur naturally in the atmosphere, include carbon dioxide , methane , nitrogen oxide, and fluorinated gases sometimes known as chlorofluorocarbons (CFCs). Greenhouse gases let the sun’s light shine onto Earth’s surface, but they trap the heat that reflects back up into the atmosphere. In this way, they act like the insulating glass walls of a greenhouse. The greenhouse effect keeps Earth’s climate comfortable. Without it, surface temperatures would be cooler by about 33 degrees Celsius (60 degrees Fahrenheit), and many life forms would freeze . Since the Industrial Revolution in the late 1700s and early 1800s, people have been releasing large 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 carbon dioxide, the most important greenhouse gas, rose by about 80 percent during that time. The amount of carbon dioxide in the atmosphere today far exceeds the natural range seen over the last 650,000 years. Most of the carbon dioxide that people put into the atmosphere comes from burning fossil fuels such as oil , coal , and natural gas . Cars, trucks, trains, and planes all burn fossil fuels. Many electric power plants also burn fossil fuels. Another way people release carbon dioxide into the atmosphere is by cutting down forests . This happens for two reasons. Decaying plant material, including trees, releases tons of carbon dioxide into the atmosphere. Living trees absorb carbon dioxide. By diminishing the number of trees to absorb carbon dioxide, the gas remains in the atmosphere. Most methane in the atmosphere comes from livestock farming , landfills , and fossil fuel production such as coal mining and natural gas processing. Nitrous oxide comes from agricultural technology and fossil fuel burning. Fluorinated gases include chlorofluorocarbons, hydrochlorofluorocarbons , and hydrofluorocarbons. These greenhouse gases are used in aerosol cans and refrigeration. All of these human activities add greenhouse gases to the atmosphere, trapping more heat than usual and contributing to global warming. Effects of Global Warming Even slight rises 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 drains into the oceans, causing sea levels to rise and oceans to become less salty. Ice sheets and glaciers advance and retreat naturally. As Earth’s temperature has changed, the ice sheets have grown and shrunk, and sea levels have fallen and risen. Ancient corals found on land in Florida, Bermuda, and the Bahamas show that the sea level must have been five to six meters (16-20 feet) higher 130,000 years ago than it is today. Earth doesn’t need to become oven-hot to melt the glaciers. Northern summers were just three to five degrees Celsius (five to nine degrees Fahrenheit) warmer during the time of those ancient fossils than they are today. However, the speed at which global warming is taking place is unprecedented . The effects are unknown. Glaciers and ice caps cover about 10 percent of the world’s landmass today. They hold about 75 percent of the world’s fresh water. If all of this ice melted, sea levels would rise by about 70 meters (230 feet). The IPCC reported that the global sea level rose about 1.8 millimeters (0.07 inches) per year from 1961 to 1993, and 3.1 millimeters (0.12 inches) per year since 1993. Rising sea levels could flood coastal communities, displacing millions of people in areas such as Bangladesh, the Netherlands, and the U.S. state of Florida. Forced migration would impact not only those areas, but the regions to which the “ climate refugees ” flee . 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. Glacial melt has already raised the global sea level slightly. However, scientists are discovering ways the sea level could increase even faster. For example, the melting of the Chacaltaya Glacier in Bolivia has exposed dark rocks beneath it. The rocks absorb heat from the sun, speeding up the melting process. Many scientists use the term “climate change” instead of “global warming.” This is because greenhouse gas emissions affect more than just temperature. Another effect involves changes in precipitation like rain and snow . Patterns in precipitation may change or become more extreme. 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 parts of southern Asia. Future Changes Nobody can look into a crystal ball and predict the future with certainty. However, scientists can make estimates about future population growth, greenhouse gas emissions, and other factors that affect climate. They can enter those estimates into computer models to find out the most likely effects of global warming. The IPCC predicts that greenhouse gas emissions will continue to increase over the next few decades . As a result, they predict the average global temperature will increase by about 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade. Even if we reduce greenhouse gas and aerosol emissions to their 2000 levels, we can still expect a warming of about 0.1 degree Celsius (0.18 degrees Fahrenheit) per decade. The panel also predicts global warming will contribute to some serious changes in water supplies around the world. By the middle of the 21st century, the IPCC predicts, river runoff and water availability will most likely increase at high latitudes and in some tropical areas. However, many dry regions in the mid-latitudes and tropics will experience a decrease in water resources. As a result, millions of people may be exposed to water shortages . Water shortages decrease the amount of water available for drinking, electricity , and hygiene . Shortages also reduce water used for irrigation. Agricultural output would slow and food prices would climb. Consistent years of drought in the Great Plains of the United States and Canada would have this effect. IPCC data also suggest that the frequency of heat waves and extreme precipitation will increase. Weather patterns such as storms and tropical cyclones will become more intense. Storms themselves may be stronger, more frequent, and longer-lasting. They would be followed by stronger storm surges , the immediate rise in sea level following storms. Storm surges are particularly damaging to coastal areas because their effects (flooding, erosion , damage to buildings and crops) are lasting. What We Can Do Reducing our greenhouse gas emissions is a critical step in slowing the global warming trend. Many governments around the world are working toward this goal. The biggest effort so far has been the Kyoto Protocol , which was adopted in 1997 and went into effect in 2005. By the end of 2009, 187 countries had signed and ratified the agreement. Under the protocol , 37 industrialized countries and the European Union have committed to reducing their greenhouse gas emissions. There are several ways that governments, industries, and individuals can reduce greenhouse gases. We can improve energy efficiency in homes and businesses. We can improve the fuel efficiency of cars and other vehicles. We can also support development of alternative energy sources, such as solar power and biofuels , that don’t involve burning fossil fuels. Some scientists are working to capture carbon dioxide and store it underground, rather than let it go into the atmosphere. This process is called carbon sequestration . Trees and other plants absorb carbon dioxide as they grow. Protecting existing forests and planting new ones can help balance greenhouse gases in the atmosphere. Changes in farming practices could also reduce greenhouse gas emissions. For example, farms use large amounts of nitrogen-based fertilizers , which increase nitrogen oxide emissions from the soil. Reducing the use of these fertilizers would reduce the amount of this greenhouse gas in the atmosphere. The way farmers handle animal manure can also have an effect on global warming. When manure is stored as liquid or slurry in ponds or tanks, it releases methane. When it dries as a solid, however, it does not. Reducing greenhouse gas emissions is vitally important. However, the global temperature has already changed and will most likely continue to change for years to come. The IPCC suggests that people explore ways to adapt to global warming as well as try to slow or stop it. Some of the suggestions for adapting include:

Expanding water supplies through rain catchment , conservation , reuse, and desalination .
Adjusting crop locations, variety, and planting dates.
Building seawalls and storm surge barriers and creating marshes and wetlands as buffers against rising sea levels .
Creating heat-health action plans , boosting emergency medical services, and improving disease surveillance and control.
Diversifying tourism attractions, because existing attractions like ski resorts and coral reefs may disappear.
Planning for roads and rail lines to cope with warming and/or flooding.
Strengthening energy infrastructure , improving energy efficiency, and reducing dependence on single sources of energy.

Barking up the Wrong Tree Spruce bark beetles in the U.S. state of Alaska have had a population boom thanks to 20 years of warmer-than-average summers. The insects have managed to chew their way through 1.6 million hectares (four million acres) of spruce trees.

Disappearing Penguins Emperor penguins ( Aptenodytes forsteri ) made a showbiz splash in the 2005 film March of the Penguins . Sadly, their encore might include a disappearing act. In the 1970s, an abnormally long warm spell caused these Antarctic birds' population to drop by 50 percent. Some scientists worry that continued global warming will push the creatures to extinction by changing their habitat and food supply.

Shell Shock A sudden increase in the amount of carbon dioxide in the atmosphere does more than change Earth's temperature. A lot of the carbon dioxide in the air dissolves into seawater. There, it forms carbonic acid in a process called ocean acidification. Ocean acidification is making it hard for some sea creatures to build shells and skeletal structures. This could alter the ecological balance in the oceans and cause problems for fishing and tourism industries.

Audio & Video

Worksheets & handouts, media credits.

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Illustrators

Educator reviewer, last updated.

October 19, 2023

User Permissions

For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.

If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

Text on this page is printable and can be used according to our Terms of Service .

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.

Related Resources

New to Climate Change?

Greenhouse gases.

Greenhouse gases are gases—like carbon dioxide (CO 2 ), methane, and nitrous oxide—that keep the Earth warmer than it would be without them. The reason they warm the Earth has to do with the way energy enters and leaves our atmosphere . When energy from the sun first reaches us, it does so mainly as light. But when that same energy leaves the Earth, it does so as infrared radiation, which we experience as heat. Greenhouse gases reflect infrared radiation, so some of the heat leaving the Earth bounces off the greenhouse gases in our atmosphere and comes back to the Earth’s surface. This is called the “greenhouse effect,” in a comparison to the heat-trapping glass on a greenhouse.

The greenhouse effect is not a bad thing. Without it, our planet would be too cold for life as we know it. But if the amount of greenhouse gases in the atmosphere changes, the strength of the greenhouse effect changes too. This is the cause of human-made climate change: by adding greenhouse gases to the atmosphere, we are trapping more heat, and the entire planet gets warmer.

The focus on “carbon”

For climate change, the most important greenhouse gas is carbon dioxide, which is why you hear so many references to “carbon” when people talk about climate change. There are three main reasons CO 2 is so central to the global warming happening today. First, there is just so much of it: we now add over 35 billion tons of CO 2 to the atmosphere every year, mostly by burning carbon-rich fuel like coal and oil that had previously been trapped in the ground. Second, it lasts a long time in the atmosphere. The CO 2 we emit today will stay above us reflecting heat for hundreds of years. This means that, even if we stop all new CO 2 emissions tomorrow, it will take many lifetimes before the warming effect of our past emissions fades away.

Finally, many different industries rely on carbon-rich fuels or other processes that give off CO 2 . That includes burning fossil fuels for electricity and heat and to power our vehicles, but it also includes manufacturing concrete and steel , the refining process for raw oil and gas, fermentation (for instance, to make alcohol or pharmaceuticals), and the decay of plant matter (like after trees are cut down ). All of these sectors can make changes to emit less CO 2 , but the same solutions won’t work for all of them.

Infographic: Other greenhouse gases. CO2 is the biggest cause of human-made climate change, but other greenhouse gases are important too. They come from different sources, linger in the atmosphere for different amounts of time, and may be more or less potent at trapping heat. Greenhouse gases are usually counted in “CO2 equivalents” (CO2e). One CO2e is the amount of heat an equal amount of CO2 would be expected to trap over the next 100 years.

Updated May 22, 2023. This Explainer was adapted from “ Explained: Greenhouse Gases ” by David Chandler, which originally appeared in MIT News.

More Resources for Learning

Keep exploring.

With more Explainers from our library:

Radiative Forcing

Carbon Pricing

The Paris Agreement

Mit climate news in your inbox.

school Campus Bookshelves
menu_book Bookshelves
perm_media Learning Objects
login Login
how_to_reg Request Instructor Account
hub Instructor Commons
Download Page (PDF)
Download Full Book (PDF)
Periodic Table
Physics Constants
Scientific Calculator
Reference & Cite
Tools expand_more
Readability

selected template will load here

This action is not available.

21.1: The Greenhouse Effect and Climate Change

Last updated
Save as PDF
Page ID 47008

Melissa Ha and Rachel Schleiger
Yuba College & Butte College via ASCCC Open Educational Resources Initiative

Earth’s Temperature is a Balancing Act

Earth’s temperature depends on the balance between energy entering and leaving the planet. When incoming energy from the sun is absorbed, Earth warms. When the sun’s energy is reflected back into space, Earth avoids warming. When energy is released from Earth into space, the planet cools. Many factors, both natural and human, can cause changes in Earth’s energy balance, including:

Changes in the greenhouse effect, which affects the amount of heat retained by Earth’s atmosphere;
Variations in the sun’s energy reaching Earth;
Changes in the reflectivity of Earth’s atmosphere and surface.

Scientists have pieced together a picture of Earth’s climate, dating back hundreds of thousands of years, by analyzing a number of indirect measures of climate such as ice cores, tree rings, glacier size, pollen counts, and ocean sediments. Scientists have also studied changes in Earth’s orbit around the sun and the activity of the sun itself.

The historical record shows that the climate varies naturally over a wide range of time scales. In general, climate changes prior to the Industrial Revolution in the 1700s can be explained by natural causes, such as changes in solar energy, volcanic eruptions, and natural changes in greenhouse gas (GHG) concentrations. Recent changes in climate , however, cannot be explained by natural causes alone. Research indicates that natural causes are very unlikely to explain most observed warming, especially warming since the mid-20th century. Rather, human activities, especially our combustion of fossil fuels, explains the current warming (figure $\PageIndex{a}$). The scientific consensus is clear: through alterations of the carbon cycle, humans are changing the global climate by increasing the effects of something known as the greenhouse effect.

The Greenhouse Effect Causes the Atmosphere to Retain Heat

Gardeners that live in moderate or cool environments use greenhouses because they trap heat and create an environment that is warmer than outside temperatures. This is great for plants that like heat, or are sensitive to cold temperatures, such as tomato and pepper plants. Greenhouses contain glass or plastic that allow visible light from the sun to pass. This light, which is a form of energy, is absorbed by plants, soil, and surfaces and heats them. Some of that heat energy is then radiated outwards in the form of infrared radiation, a different form of energy. Unlike with visible light, the glass of the greenhouse blocks the infrared radiation, thereby trapping the heat energy, causing the temperature within the greenhouse to increase.

The same phenomenon happens inside a car on a sunny day. Have you ever noticed how much hotter a car can get compared to the outside temperature? Light energy from the sun passes through the windows and is absorbed by the surfaces in the car such as seats and the dashboard. Those warm surfaces then radiate infrared radiation, which cannot pass through the glass. This trapped infrared energy causes the air temperatures in the car to increase. This process is commonly known as the greenhouse effect .

The video below made for kids, but provides a clear and simple introduction to the greenhouse effect.

The greenhouse effect also happens with the entire Earth. Of course, our planet is not surrounded by glass windows. Instead, the Earth is wrapped with an atmosphere that contains greenhouse gases (GHGs). Much like the glass in a greenhouse, GHGs allow incoming visible light energy from the sun to pass, but they block infrared radiation that is radiated from the Earth towards space (figure $\PageIndex{b}$). In this way, they help trap heat energy that subsequently raises air temperature. Being a greenhouse gas is a physical property of certain types of gases; because of their molecular structure they absorb wavelengths of infrared radiation, but are transparent to visible light. Some notable greenhouse gases are water vapor (H 2 O), carbon dioxide (CO 2 ), and methane (CH 4 ). GHGs act like a blanket, making Earth significantly warmer than it would otherwise be. Scientists estimate that average temperature on Earth would be -18º C without naturally-occurring GHGs.

Heat from solar radiation is trapped by the atmosphere. Human activities increase greenhouse gases resulting in an enhanced greenhouse effect.

What is Global Warming?

Global warming refers to the recent and ongoing rise in global average temperature near Earth’s surface. It is caused mostly by increasing concentrations of greenhouse gases in the atmosphere. Global warming is causing climate patterns to change. However, global warming itself represents only one aspect of climate change.

What is Climate Change?

Climate change refers to any significant change in the measures of climate lasting for an extended period of time. In other words, climate change includes major changes in temperature, precipitation, or wind patterns, among other effects, that occur over several decades or longer.

The Main Greenhouse Gasses

The most important GHGs directly emitted by humans include CO 2 and methane. Carbon dioxide (CO 2 ) is the primary greenhouse gas that is contributing to recent global climate change. CO 2 is a natural component of the carbon cycle, involved in such activities as photosynthesis, respiration, volcanic eruptions, and ocean-atmosphere exchange. Human activities, primarily the burning of fossil fuels and changes in land use, release very large amounts of CO 2 to the atmosphere, causing its concentration in the atmosphere to rise.

Atmospheric CO 2 concentrations have increased by 45% since pre-industrial times, from approximately 280 parts per million (ppm) in the 18th century to 409.8 ppm in 2019 (figure $\PageIndex{c}$). The current CO 2 level is higher than it has been in at least 800,000 years, based on evidence from ice cores that preserve ancient atmospheric gases (figure $\PageIndex{d-f}$). Human activities currently release over 30 billion tons of CO 2 into the atmosphere every year. While some volcanic eruptions released large quantities of CO 2 in the distant past, the U.S. Geological Survey (USGS) reports that human activities now emit more than 135 times as much CO 2 as volcanoes each year. This human-caused build-up of CO 2 in the atmosphere is like a tub filling with water, where more water flows from the faucet than the drain can take away.

Line graph shows an increase in atmospheric carbon dioxide over time with fluctuations between seasons each year

Other Greenhouse Gasses

Although this concentration is far less than that of CO 2 , methane (CH 4 ) is 28 times as potent a greenhouse gas. Methane is produced when bacteria break down organic matter under anaerobic conditions and can be released due to natural or anthropogenic processes. Anaerobic conditions can happen when organic matter is trapped underwater (such as in rice paddies) or in the intestines of herbivores. Anthropogenic causes now account for 60% of total methane release. Examples include agriculture, fossil fuel extraction and transport, mining, landfill use, and burning of forests. Specifically, raising cattle releases methane due to fermentation in their rumens produces methane that is expelled from their GI tract. Methane is more abundant in Earth’s atmosphere now than at any time in at least the past 650,000 years, and CH 4 concentrations increased sharply during most of the 20th century. They are now more than two and-a-half times pre-industrial levels (1.9 ppm), but the rate of increase has slowed considerably in recent decades.

Water vapor is the most abundant greenhouse gas and also the most important in terms of its contribution to the natural greenhouse effect, despite having a short atmospheric lifetime. Some human activities can influence local water vapor levels. However, on a global scale, the concentration of water vapor is controlled by temperature, which influences overall rates of evaporation and precipitation. Therefore, the global concentration of water vapor is not substantially affected by direct human emissions.

Ground-level ozone (O 3 ), which also has a short atmospheric lifetime, is a potent greenhouse gas. Chemical reactions create ozone from emissions of nitrogen oxides and volatile organic compounds from automobiles, power plants, and other industrial and commercial sources in the presence of sunlight (as discussed in section 10.1). In addition to trapping heat, ozone is a pollutant that can cause respiratory health problems and damage crops and ecosystems.

Changes in the Sun’s Energy Affect how Much Energy Reaches Earth

Climate can be influenced by natural changes that affect how much solar energy reaches Earth. These changes include changes within the sun and changes in Earth’s orbit. Changes occurring in the sun itself can affect the intensity of the sunlight that reaches Earth’s surface. The intensity of the sunlight can cause either warming (during periods of stronger solar intensity) or cooling (during periods of weaker solar intensity). The sun follows a natural 11-year cycle of small ups and downs in intensity, but the effect on Earth’s climate is small. Changes in the shape of Earth’s orbit as well as the tilt and position of Earth’s axis can also affect the amount of sunlight reaching Earth’s surface.

Changes in the sun’s intensity have influenced Earth’s climate in the past. For example, the so-called “ Little Ice Age ” between the 17th and 19th centuries may have been partially caused by a low solar activity phase from 1645 to 1715, which coincided with cooler temperatures. The Little Ice Age refers to a slight cooling of North America, Europe, and probably other areas around the globe. Changes in Earth’s orbit have had a big impact on climate over tens of thousands of years. These changes appear to be the primary cause of past cycles of ice ages, in which Earth has experienced long periods of cold temperatures (ice ages), as well as shorter interglacial periods (periods between ice ages) of relatively warmer temperatures.

Changes in solar energy continue to affect climate. However, solar activity has been relatively constant, aside from the 11-year cycle, since the mid-20th century and therefore does not explain the recent warming of Earth. Similarly, changes in the shape of Earth’s orbit as well as the tilt and position of Earth’s axis affect temperature on relatively long timescales (tens of thousands of years), and therefore cannot explain the recent warming.

Changes in Reflectivity Affect How Much Energy Enters Earth’s System

When sunlight energy reaches Earth it can be reflected or absorbed. The amount that is reflected or absorbed depends on Earth’s surface and atmosphere. Light-colored objects and surfaces, like snow and clouds, tend to reflect most sunlight, while darker objects and surfaces, like the ocean and forests, tend to absorb more sunlight. The term albedo refers to the amount of solar radiation reflected from an object or surface, often expressed as a percentage. Earth as a whole has an albedo of about 30%, meaning that 70% of the sunlight that reaches the planet is absorbed. Sunlight that is absorbed warms Earth’s land, water, and atmosphere.

Albedo is also affected by aerosols. Aerosols are small particles or liquid droplets in the atmosphere that can absorb or reflect sunlight. Unlike greenhouse gases (GHGs), the climate effects of aerosols vary depending on what they are made of and where they are emitted. Those aerosols that reflect sunlight, such as particles from volcanic eruptions or sulfur emissions from burning coal, have a cooling effect. Those that absorb sunlight, such as black carbon (a part of soot), have a warming effect.

Natural changes in albedo, like the melting of sea ice or increases in cloud cover, have contributed to climate change in the past, often acting as feedbacks to other processes. Volcanoes have played a noticeable role in climate. Volcanic particles that reach the upper atmosphere can reflect enough sunlight back to space to cool the surface of the planet by a few tenths of a degree for several years. Volcanic particles from a single eruption do not produce long-term change because they remain in the atmosphere for a much shorter time than GHGs.

Human changes in land use and land cover have changed Earth’s albedo. Processes such as deforestation, reforestation, desertification, and urbanization often contribute to changes in climate in the places they occur. These effects may be significant regionally, but are smaller when averaged over the entire globe.

Scientific Consensus: Global Climate Change is Real

The Intergovernmental Panel on Climate Change (IPCC) was created in 1988 by the United Nations Environment Programme and the World Meteorological Organization. It is charged with the task of evaluating and synthesizing the scientific evidence surrounding global climate change. The IPCC uses this information to evaluate current impacts and future risks, in addition to providing policymakers with assessments. These assessments are released about once every every six years. The most recent report, the 5th Assessment, was released in 2013. Hundreds of leading scientists from around the world are chosen to author these reports. Over the history of the IPCC, these scientists have reviewed thousands of peer-reviewed, publicly available studies. The scientific consensus is clear: global climate change is real and humans are very likely the cause for this change.

Additionally, the major scientific agencies of the United States, including the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA), also agree that climate change is occurring and that humans are driving it. In 2010, the US National Research Council concluded that “Climate change is occurring, is very likely caused by human activities, and poses significant risks for a broad range of human and natural systems”. Many independent scientific organizations have released similar statements, both in the United States and abroad. This doesn’t necessarily mean that every scientist sees eye to eye on each component of the climate change problem, but broad agreement exists that climate change is happening and is primarily caused by excess greenhouse gases from human activities. Critics of climate change, driven by ideology instead of evidence, try to suggest to the public that there is no scientific consensus on global climate change. Such an assertion is patently false.

Current Status of Global Climate Change and Future Changes

Greenhouse gas concentrations in the atmosphere will continue to increase unless the billions of tons of anthropogenic emissions each year decrease substantially. Increased concentrations are expected to do the following:

Increase Earth’s average temperature (figure $\PageIndex{g}$),
Influence the patterns and amounts of precipitation,
Reduce ice and snow cover, as well as permafrost,
Raise sea level (figure $\PageIndex{h}$),
Increase the acidity of the oceans.

Line graph shows overall increases in sea height from 1993 to 2020

Figure $\PageIndex{h}$: Sea height variation (mm) over time. Sea height has increased about 3.3 millimeters per year on average since 1993. Data is from satellite sea level observations by the NASA Goddard Space Flight Center. Image by NASA (public domain).

These changes will impact our food supply, water resources, infrastructure, ecosystems, and even our own health. The magnitude and rate of future climate change will primarily depend on the following factors:

The rate at which levels of greenhouse gas concentrations in our atmosphere continue to increase,
How strongly features of the climate (e.g., temperature, precipitation, and sea level) respond to the expected increase in greenhouse gas concentrations,
Natural influences on climate (e.g., from volcanic activity and changes in the sun’s intensity) and natural processes within the climate system (e.g., changes in ocean circulation patterns).

Past and Present-day GHG Emissions Will Affect Climate Far into the Future

Many greenhouse gases stay in the atmosphere for long periods of time. As a result, even if emissions stopped increasing, atmospheric greenhouse gas concentrations would continue to remain elevated for hundreds of years. Moreover, if we stabilized concentrations and the composition of today’s atmosphere remained steady (which would require a dramatic reduction in current greenhouse gas emissions), surface air temperatures would continue to warm. This is because the oceans, which store heat, take many decades to fully respond to higher greenhouse gas concentrations. The ocean’s response to higher greenhouse gas concentrations and higher temperatures will continue to impact climate over the next several decades to hundreds of years.

Future Temperature Changes

Climate models project the following key temperature-related changes:

Average global temperatures are expected to increase by 2°F to 11.5°F by 2100, depending on the level of future greenhouse gas emissions, and the outcomes from various climate models.
By 2100, global average temperature is expected to warm at least twice as much as it has during the last 100 years.
Ground-level air temperatures are expected to continue to warm more rapidly over land than oceans.
Some parts of the world are projected to see larger temperature increases than the global average.

Future Precipitation and Storm Events

Patterns of precipitation and storm events, including both rain and snowfall are likely to change. However, some of these changes are less certain than the changes associated with temperature. Projections show that future precipitation and storm changes will vary by season and region. Some regions may have less precipitation, some may have more precipitation, and some may have little or no change. The amount of rain falling in heavy precipitation events is likely to increase in most regions, while storm tracks are projected to shift towards the poles. Climate models project the following precipitation and storm changes:

Global average annual precipitation through the end of the century is expected to increase, although changes in the amount and intensity of precipitation will vary by region.
The intensity of precipitation events will likely increase on average. This will be particularly pronounced in tropical and high-latitude regions, which are also expected to experience overall increases in precipitation.
The strength of the winds associated with tropical storms is likely to increase. The amount of precipitation falling in tropical storms is also likely to increase.
Annual average precipitation is projected to increase in some areas and decrease in others.

Future Ice, Snowpack, and Permafrost

Arctic sea ice is already declining drastically. The area of snow cover in the Northern Hemisphere has decreased since 1970. Permafrost temperature has increased over the last century, making it more susceptible to thawing. Over the next century, it is expected that sea ice will continue to decline, glaciers will continue to shrink, snow cover will continue to decrease, and permafrost will continue to thaw.

For every 2°F of warming, models project about a 15% decrease in the extent of annually averaged sea ice and a 25% decrease in September Arctic sea ice. The coastal sections of the Greenland and Antarctic ice sheets are expected to continue to melt or slide into the ocean. If the rate of this ice melting increases in the 21st century, the ice sheets could add significantly to global sea level rise. Glaciers are expected to continue to decrease in size. The rate of melting is expected to continue to increase, which will contribute to sea level rise.

Future Sea Level Change

Warming temperatures contribute to sea level rise by expanding ocean water, melting mountain glaciers and ice caps, and causing portions of the Greenland and Antarctic ice sheets to melt or flow into the ocean. Since 1870, global sea level has risen by about 8 inches. Estimates of future sea level rise vary for different regions, but global sea level for the next century is expected to rise at a greater rate than during the past 50 years. The contribution of thermal expansion, ice caps, and small glaciers to sea level rise is relatively well-studied, but the impacts of climate change on ice sheets are less understood and represent an active area of research. Thus, it is more difficult to predict how much changes in ice sheets will contribute to sea level rise. Greenland and Antarctic ice sheets could contribute an additional 1 foot of sea level rise, depending on how the ice sheets respond.

Regional and local factors will influence future relative sea level rise for specific coastlines around the world (figure $\PageIndex{i}$). For example, relative sea level rise depends on land elevation changes that occur as a result of subsidence (sinking) or uplift (rising), in addition to things such as local currents, winds, salinity, water temperatures, and proximity to thinning ice sheets. Assuming that these historical geological forces continue, a 2-foot rise in global sea level by 2100 would result in the following relative sea level rise:

2.3 feet at New York City
2.9 feet at Hampton Roads, Virginia
3.5 feet at Galveston, Texas
1 foot at Neah Bay in Washington state

The yard of a damaged house is flooded, and a tree stump is submerged

Future Ocean Acidification

Ocean acidification is the process of ocean waters decreasing in pH. Oceans become more acidic as carbon dioxide (CO 2 ) emissions in the atmosphere dissolve in the ocean. This change is measured on the pH scale, with lower values being more acidic. The pH level of the oceans has decreased by approximately 0.1 pH units since pre-industrial times, which is equivalent to a 25% increase in acidity. The pH level of the oceans is projected to decrease even more by the end of the century as CO 2 concentrations are expected to increase for the foreseeable future. Ocean acidification adversely affects many marine species, including plankton, mollusks, shellfish, and corals. As ocean acidification increases, the availability of calcium carbonate will decline. Calcium carbonate is a key building block for the shells and skeletons of many marine organisms. If atmospheric CO 2 concentrations double, coral calcification rates are projected to decline by more than 30%. If CO 2 concentrations continue to rise at their current rate, corals could become rare on tropical and subtropical reefs by 2050.

Mismatched Interactions

Climate change also affects phenology, the study of the effects of climatic conditions on the timing of periodic lifecycle events, such as flowering in plants or migration in birds. Researchers have shown that 385 plant species in Great Britain are flowering 4.5 days sooner than was recorded earlier during the previous 40 years. In addition, insect-pollinated species were more likely to flower earlier than wind-pollinated species. The impact of changes in flowering date would be mitigated if the insect pollinators emerged earlier. This mismatched timing of plants and pollinators could result in injurious ecosystem effects because, for continued survival, insect-pollinated plants must flower when their pollinators are present.

Likewise, migratory birds rely on daylength cues, which are not influenced by climate change. Their insect food sources, however, emerge earlier in the year in response to warmer temperatures. As a result, climate change decreases food availability for migratory bird species.

Spread of Disease

This rise in global temperatures will increase the range of disease-carrying insects and the viruses and pathogenic parasites they harbor. Thus, diseases will spread to new regions of the globe. This spread has already been documented with dengue fever, a disease the affects hundreds of millions per year, according to the World Health Organization. Colder temperatures typically limit the distribution of certain species, such as the mosquitoes that transmit malaria, because freezing temperatures destroy their eggs.

Not only will the range of some disease-causing insects expand, the increasing temperatures will also accelerate their lifecycles, which allows them to breed and multiply quicker, and perhaps evolve pesticide resistance faster. In addition to dengue fever, other diseases are expected to spread to new portions of the world as the global climate warms. These include malaria, yellow fever, West Nile virus, zika virus, and chikungunya.

Climate change does not only increase the spread of diseases in humans. Rising temperatures are associated with greater amphibian mortality due to chytridiomycosis (see Invasive Species ). Similarly, warmer temperatures have exacerbated bark beetle infestations of coniferous trees, such as pine an spruce.

Climate Change Affects Everyone

Our lives are connected to the climate . Human societies have adapted to the relatively stable climate we have enjoyed since the last ice age which ended several thousand years ago. A warming climate will bring changes that can affect our water supplies, agriculture, power and transportation systems, the natural environment, and even our own health and safety.

Carbon dioxide can stay in the atmosphere for nearly a century, on average, so Earth will continue to warm in the coming decades. The warmer it gets, the greater the risk for more severe changes to the climate and Earth’s system. Although it’s difficult to predict the exact impacts of climate change, what’s clear is that the climate we are accustomed to is no longer a reliable guide for what to expect in the future.

We can reduce the risks we will face from climate change . By making choices that reduce greenhouse gas pollution, and preparing for the changes that are already underway, we can reduce risks from climate change. Our decisions today will shape the world our children and grandchildren will live in.

You can take steps at home, on the road, and in your office to reduce greenhouse gas emissions and the risks associated with climate change. Many of these steps can save you money. Some, such as walking or biking to work, can even improve your health! You can also get involved on a local or state level to support energy efficiency, clean energy programs, or other climate programs.

Attributions

Modified by Melissa Ha from the following sources:

Climate and the Effects of Global Climate Change from General Biology by OpenStax (licensed under CC-BY )
Climate Change from Environmental Biology by Matthew R. Fisher (licensed under CC-BY )
Carbon Cycle from Biology by John W. Kimball (licensed under CC-BY )

Greenhouse gases: Causes, sources and environmental effects

Greenhouse gases help keep the Earth at a habitable temperature — until there is too much of them.

Greenhouse gases are being emitted into the atmosphere with dire consequences. Here, a factory emits a harmful gas.

Solar radiation and the "greenhouse effect"

Global warming
Future outlook

Additional resources

Behind the phenomena of global warming and climate change lies the increase in greenhouse gases in our atmosphere. A greenhouse gas is any gaseous compound in the atmosphere that is capable of absorbing infrared radiation , thereby trapping and holding heat in the atmosphere. By increasing the heat in the atmosphere, greenhouse gases are responsible for the greenhouse effect, which ultimately leads to global warming. (The effects of global warming can been seen across the globe.)

Related: 10 signs that Earth's climate is off the rails

Global warming isn't a recent scientific concept. The basics of the phenomenon were worked out well over a century ago by Swedish physicist and chemist Svante Arrhenius, in 1896. His paper, published in the Philosophical Magazine and Journal of Science , was the first to quantify the contribution of carbon dioxide to what scientists now call the " greenhouse effect ."

The greenhouse effect occurs because the sun bombards Earth with enormous amounts of radiation that strike Earth's atmosphere in the form of visible light, plus ultraviolet (UV), infrared (IR) and other types of radiation that are invisible to the human eye. UV radiation has a shorter wavelength and a higher energy level than visible light, while IR radiation has a longer wavelength and a weaker energy level. About 30% of the radiation that strikes Earth is reflected back out to space by clouds, ice and other reflective surfaces. The remaining 70% is absorbed by the oceans, the land and the atmosphere, according to NASA's Earth Observatory .

As they heat up, the oceans, land and atmosphere release heat in the form of IR thermal radiation, which passes out of the atmosphere and into space. It's this equilibrium of incoming and outgoing radiation that makes the Earth habitable, with an average temperature of about 59 degrees Fahrenheit (15 degrees Celsius), according to NASA. Without this atmospheric equilibrium, Earth would be as cold and lifeless as its moon, or as blazing hot as Venus. The moon, which has almost no atmosphere, is about minus 243 F (minus 153 C) on its dark side. Venus, on the other hand, has a very dense atmosphere that traps solar radiation; the average temperature on Venus is about 864 F (462 C).

The exchange of incoming and outgoing radiation that warms the Earth is often referred to as the greenhouse effect because an agricultural greenhouse works in much the same way. Incoming shortwave UV radiation easily passes through the glass walls of a greenhouse and is absorbed by the plants and hard surfaces inside. Weaker, longwave IR radiation, however, has difficulty passing through the glass walls and is thereby trapped inside, warming the greenhouse.

How greenhouse gases cause global warming

The gases in the atmosphere that absorb radiation are known as "greenhouse gases" (abbreviated as GHG) because they are largely responsible for the greenhouse effect. The greenhouse effect, in turn, is one of the leading causes of global warming. The most significant greenhouse gases, according to the Environmental Protection Agency (EPA), are: water vapor (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O).

"While oxygen (O2) is the second most abundant gas in our atmosphere, O2 does not absorb thermal infrared radiation," Michael Daley, an associate professor of environmental science at Lasell College in Massachusetts, told Live Science.

Global warming and the greenhouse gases that cause it occur naturally — without them, Earth's average surface temperature would be a gelid zero degrees F (minus 18 C). But the amount of greenhouse gases in the atmosphere has skyrocketed to detrimental levels in recent history.

Related: Carbon dioxide soars to record breaking levels not seen in at least 800,000 years

During the 20,000-year period before the Industrial Revolution, atmospheric CO2 fluctuated between about 180 parts per million (ppm) during ice ages and 280 ppm during interglacial warm periods. However, since the beginning of the Industrial Revolution in the 1750s, the amount of CO2 has risen nearly 50%, according to NASA’s Global Climate Change portal . Today, CO2 levels stand at over 410 ppm.

Fluorinated gases — gases to which the element fluorine has been added — are created during industrial processes and are also considered greenhouse gases. These include hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride. Although they are present in the atmosphere in very small concentrations, they trap heat very effectively, making them high "global warming potential" (GWP) gases.

Chlorofluorocarbons (CFCs), once used as refrigerants and aerosol propellants until they were phased out by international agreement, are also greenhouse gases.

Related: Global warming vs. solar cooling: The showdown begins in 2020

There are three factors that affect the degree to which a greenhouse gas will influence global warming: Its abundance in the atmosphere, how long it stays in the atmosphere and its GWP. For example, water vapor is the most abundant greenhouse gas, but carbon dioxide has a more significant impact on global warming due to its abundance in the atmosphere plus its relatively long atmospheric lifetime of 300 to 1,000 years, according to NASA . Water vapor, on the other hand, has an atmospheric lifetime of no more than 10 days, according to a 2020 study published in the Journal of the Atmospheric Sciences .

Methane is about 21 times more efficient at absorbing radiation than CO2, giving it a higher GWP rating, even though it stays in the atmosphere for only about 12 years, according to the United Nations Framework Convention on Climate Change (UNFCCC) . Although methane and other GHGs are capable of trapping more heat than CO2, scientists still consider carbon dioxide to be the dominant greenhouse gas because its warming effect outlives the others' effects by centuries.

Sources of greenhouse gases

Some greenhouse gases, such as methane, are produced through agricultural practices, in the form of livestock manure, for example. Others, like CO2, largely result from natural processes like respiration, and from the burning of fossil fuels like coal, oil and gas.

Another primary source of CO2 is deforestation . When trees are felled to produce goods or heat, they release the carbon that is normally stored for photosynthesis . This process releases up to 4.8 billion metric tons of carbon into the atmosphere every year, according to the World Resources Institute .

Forestry and other land-use practices can offset some of these greenhouse gas emissions. "Replanting helps to reduce the buildup of carbon dioxide in the atmosphere as growing trees sequester carbon dioxide through photosynthesis," Daley told Live Science. "However, forests cannot sequester all of the carbon dioxide we are emitting to the atmosphere through the burning of fossil fuels, and a reduction in fossil fuel emissions is still necessary to avoid buildup in the atmosphere."

Worldwide, the output of greenhouse gases is a source of grave concern. According to NOAA’s Climate.gov , over the past 60 years, atmospheric CO2 has increased at an annual rate that's 100 times faster than previous natural increases. The last time global atmospheric CO2 amounts were this high was 3 million years ago, when temperatures were up to 5.4 degrees F (3 degrees C) higher than during the pre-industrial era. As a result of modern-day CO2-induced global warming, 2016 was the warmest year on record, with 2019 and 2020 ranking as the next warmest, respectively. In fact, the six hottest years on record have all occurred since 2015, according to the World Meteorological Organization .

"The warming we observe affects atmospheric circulation, which impacts rainfall patterns globally," said Josef Werne, an associate professor in the Department of Geology and Planetary Science at the University of Pittsburgh. "This will lead to big environmental changes, and challenges, for people all across the globe."

Our planet's future

If current trends continue, scientists, government officials and a growing number of citizens fear that the worst effects of global warming — extreme weather, rising sea levels , plant and animal extinctions, ocean acidification , major shifts in climate and unprecedented social upheaval — will be inevitable.

In an effort to combat GHG-induced global warming, the U.S. government created a climate action plan in 2013. And in April 2016, representatives from 73 countries signed the Paris Agreement , an international pact to combat climate change by investing in a sustainable, low-carbon future, according to the UNFCCC . Although the U.S. withdrew from the Paris Agreement in 2017, it rejoined in late-January 2021. President Biden's administration has also set a target of reducing U.S. emissions by 50-52% of 2005 levels by the year 2030. (Emissions are routinely compared to those in 2005 — the year U.S. emissions of CO2 peaked at nearly 6 billion tons.)

In 2020, global carbon dioxide emissions fell 6.4% (13% in the U.S. alone) — the first time in decades the annual rate hasn’t climbed, Nature reported . This was in part due to the decrease in fossil fuel combustion resulting from the switch to natural gas from coal , but largely because of the forced standstill in economic, social and transportation activities in response to the COVID-19 pandemic . Scientists expected the annual emissions decline to actually be larger than it was, but emissions rebounded as restrictions were lifted in some nations and activities recovered toward the end of 2020.

Related: Global carbon emissions dropped an unprecedented 17% during the coronavirus lockdown — and it changes nothing

In order to limit global warming to the 2.7 degree F (1.5 degree C) target set by the Paris Agreement, the world still needs to cut its CO2 emissions by 7.6% for the next decade, according to the UN Environment Programme .

Researchers around the world continue to work toward finding ways to lower greenhouse gas emissions and mitigate their effects. One potential solution scientists are examining is to suck some of the carbon dioxide out of the atmosphere and bury it underground indefinitely. Advocates argue that carbon capture and storage is technologically feasible , but market forces have prevented widespread adoption.

Whether or not removing already-emitted carbon from the atmosphere is feasible, preventing future warming requires stopping the emissions of greenhouse gases. The most ambitious effort to forestall warming thus far is the 2016 Paris Agreement. This nonbinding international treaty aims to keep warming "well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius," according to the United Nations. Each signatory to the treaty agreed to set their own voluntary greenhouse gas emission limits and to make them stricter over time. Climate scientists said that the emissions limits committed under the agreement wouldn't keep warming as low as 1.5 or even 2 degrees C, but that it would be an improvement over the "business-as-usual" scenario.

Find out the latest research and policy updates regarding global warming via NOAA's Climate.gov portal .
Learn more about the Global Carbon Project .
Read more about the impact of COVID-19 on 2020 CO2 emissions, according to Carbon Brief .

Sign up for the Live Science daily newsletter now

Get the world’s most fascinating discoveries delivered straight to your inbox.

Tiffany Means is a meteorologist turned science writer based in the Blue Ridge mountains of North Carolina. Her work has appeared in Yale Climate Connections, The Farmers' Almanac, and other publications. Tiffany has a bachelor's degree in atmospheric science from the University of North Carolina, Asheville, and she is earning a master's in science writing at Johns Hopkins University.

When were sea levels highest?

'Worrisome and even frightening': Ancient ecosystem of Lake Baikal at risk of regime change from warming

Strange light spotted over distant 'hell planet' may be 1st rainbow 'glory' found beyond our solar system

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.

READ FREE ONLINE

Welcome to OpenBook!

You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

Do you want to take a quick tour of the OpenBook's features?

Show this book's table of contents , where you can jump to any chapter by name.

...or use these buttons to go back to the previous chapter or skip to the next one.

Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

Switch between the Original Pages , where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

To search the entire text of this book, type in your search term here and press Enter .

Share a link to this book page on your preferred social network or via email.

View our suggested citation for this chapter.

Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

Get Email Updates

Do you enjoy reading reports from the Academies online for free ? Sign up for email notifications and we'll let you know about new publications in your areas of interest when they're released.

What Is Climate Change?

Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates. These changes have a broad range of observed effects that are synonymous with the term.

Changes observed in Earth’s climate since the mid-20th century are driven by human activities, particularly fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere, raising Earth’s average surface temperature. Natural processes, which have been overwhelmed by human activities, can also contribute to climate change, including internal variability (e.g., cyclical ocean patterns like El Niño, La Niña and the Pacific Decadal Oscillation) and external forcings (e.g., volcanic activity, changes in the Sun’s energy output , variations in Earth’s orbit ).

Scientists use observations from the ground, air, and space, along with computer models , to monitor and study past, present, and future climate change. Climate data records provide evidence of climate change key indicators, such as global land and ocean temperature increases; rising sea levels; ice loss at Earth’s poles and in mountain glaciers; frequency and severity changes in extreme weather such as hurricanes, heatwaves, wildfires, droughts, floods, and precipitation; and cloud and vegetation cover changes.

“Climate change” and “global warming” are often used interchangeably but have distinct meanings. Similarly, the terms "weather" and "climate" are sometimes confused, though they refer to events with broadly different spatial- and timescales.

What Is Global Warming?

Global warming is the long-term heating of Earth’s surface observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere. This term is not interchangeable with the term "climate change."

Since the pre-industrial period, human activities are estimated to have increased Earth’s global average temperature by about 1 degree Celsius (1.8 degrees Fahrenheit), a number that is currently increasing by more than 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade. The current warming trend is unequivocally the result of human activity since the 1950s and is proceeding at an unprecedented rate over millennia.

Weather vs. Climate

“if you don’t like the weather in new england, just wait a few minutes.” - mark twain.

Weather refers to atmospheric conditions that occur locally over short periods of time—from minutes to hours or days. Familiar examples include rain, snow, clouds, winds, floods, or thunderstorms.

Climate, on the other hand, refers to the long-term (usually at least 30 years) regional or even global average of temperature, humidity, and rainfall patterns over seasons, years, or decades.

Find Out More: A Guide to NASA’s Global Climate Change Website

This website provides a high-level overview of some of the known causes, effects and indications of global climate change:

Evidence. Brief descriptions of some of the key scientific observations that our planet is undergoing abrupt climate change.

Causes. A concise discussion of the primary climate change causes on our planet.

Effects. A look at some of the likely future effects of climate change, including U.S. regional effects.

Vital Signs. Graphs and animated time series showing real-time climate change data, including atmospheric carbon dioxide, global temperature, sea ice extent, and ice sheet volume.

Earth Minute. This fun video series explains various Earth science topics, including some climate change topics.

Other NASA Resources

Goddard Scientific Visualization Studio. An extensive collection of animated climate change and Earth science visualizations.

Sea Level Change Portal. NASA's portal for an in-depth look at the science behind sea level change.

NASA’s Earth Observatory. Satellite imagery, feature articles and scientific information about our home planet, with a focus on Earth’s climate and environmental change.

Header image is of Apusiaajik Glacier, and was taken near Kulusuk, Greenland, on Aug. 26, 2018, during NASA's Oceans Melting Greenland (OMG) field operations. Learn more here . Credit: NASA/JPL-Caltech

Discover More Topics From NASA

Explore Earth Science

Earth Science in Action

Earth Science Data

The sum of Earth's plants, on land and in the ocean, changes slightly from year to year as weather patterns shift.

Facts About Earth

November 3, 2023

Earth Reacts to Greenhouse Gases More Strongly Than We Thought

Climate scientists, including pioneer James Hansen, are pinning down a fundamental factor that drives how hot Earth will get

By Chelsea Harvey & E&E News

A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's Earth-observing satellite – Suomi NPP.

NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

CLIMATEWIRE | Climate scientist James Hansen is frustrated. And he’s worried.

For nearly 40 years, Hansen has been warning the world of the dangers of global warming. His testimony at a groundbreaking 1988 Senate hearing on the greenhouse effect helped inject the coming climate crisis into the public consciousness. And it helped make him one of the most influential climate scientists in the world.

Hansen has spent several decades as director of NASA’s Goddard Institute for Space Studies, and now at 82, he directs Columbia University’s Climate Science, Awareness and Solutions program .

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

In the years since his seminal testimony, many of Hansen’s basic scientific predictions about the Earth’s climate future have come true. Greenhouse gas emissions have grown, and global temperatures have continued to rise. The world’s glaciers and ice sheets are melting and sea level rise is accelerating.

But Hansen has been disappointed with the scientific community’s response to some of his more recent projections about the future of the warming Earth, which some researchers have characterized as unrealistically dire.

In particular, he was discouraged by the response to a paper he published in 2016, suggesting catastrophic ice melt in Greenland and Antarctica, with widespread global effects, may be possible with relatively modest future warming.

Many researchers said such outcomes were unlikely. But Hansen described the paper as some of his most important work and a warning about the need for more urgent action.

Now he’s bracing himself for a similar reaction to his latest paper , published Thursday morning.

“I expect the response to be characterized by scientific reticence,” he said in an email to E&E News.

The new paper, published in the research journal Oxford Open Climate Change , addresses a central question in modern climate science: How much will the Earth warm in response to future carbon emissions? It’s a metric known as “climate sensitivity,” or how sensitive the planet is to greenhouse gases in the atmosphere.

Hansen’s findings suggest the planet may warm faster than previous estimates have indicated. And while some experts say it’s possible, others suggest that he’s taken the results too far.

In studies, scientists often tackle the climate sensitivity question by investigating how much the Earth would warm if atmospheric carbon dioxide concentrations doubled their preindustrial levels. Prior to the industrial era, global CO2 levels hovered around 280 parts per million, meaning a doubling would land around 560 ppm.

Today’s CO2 levels have already climbed above 400 ppm, giving the question a growing relevance.

Climate sensitivity is a difficult metric to estimate. It hinges on a wide variety of feedback loops in the Earth’s climate system, which can speed up or slow down the planet’s warming.

As the Earth’s reflective glaciers and ice sheets melt, for instance, the planet can absorb more sunlight and warm at a faster rate. Forests and other natural ecosystems may absorb different amounts of carbon as the planet warms. Different types of clouds can both speed up or slow down global warming, and it’s still unclear how they will change as the Earth heats up.

The uncertainties around these factors have made it challenging for scientists to pin down an exact estimate for climate sensitivity. But they’ve chipped away at it in recent years.

For decades, studies generally suggested that the Earth should experience anywhere from 1.5 to 4.5 degrees Celsius of warming with a doubling of CO2. But a 2020 paper narrowed the range to between 2.6 and 3.9 C, using multiple lines of evidence including climate models, the Earth’s response to recent historical emissions and the Earth’s ancient climate history.

The latest assessment report from the U.N.’s Intergovernmental Panel on Climate Change adopted a similar estimate, suggesting a likely range of 2.5 to 4 C with a central estimate around 3 C.

Hansen’s new paper, published with an international group of co-authors, significantly ups the numbers. It suggests a central estimate of around 4.8 C, nearly 2 degrees higher than the IPCC’s figure.

The paper relies largely on evidence from Earth’s ancient climate history. One reason? It’s unclear whether current climate models accurately represent all the relevant feedback effects that may affect climate sensitivity, Hansen and his co-authors argue. The planet’s past provides a clearer view of how the Earth has responded to previous shifts in atmospheric carbon dioxide concentrations.

The paper also suggests that global warming is likely to proceed faster in the near term than previous studies have suggested.

Under the international Paris climate agreement, world leaders are striving to keep global warming well below 2 C and below 1.5 C if at all possible. The new paper warns that warming could exceed 1.5 C by the end of the 2020s and 2 C by 2050.

A gradual global decline in air pollution, driven by tightening environmental regulations, is part of the reasoning. Some types of air pollution are known to have a cooling effect on the climate, which may mask some of the impact of greenhouse gas emissions. As these aerosols decline in the atmosphere, some research suggests, this masking effect may fall away and global temperatures may rise at faster rates.

Hansen and his co-authors argue that better accounting for the declines in global aerosols should accelerate estimates of near-term global warming. Studies suggest that warming between 1970 and 2010 likely proceeded at around 0.18 C per decade. Post-2010, the new paper argues, that figure should rise to 0.27 C.

The findings should motivate greater urgency to not only cut greenhouse gas emissions but to eventually lower global temperatures closer to their preindustrial levels, Hansen suggests. That means using natural resources and technological means to remove carbon dioxide from the atmosphere.

Hansen also suggests that a controversial form of geoengineering, known as solar radiation management, is likely warranted. SRM, in theory, would use reflective aerosols to beam sunlight away from the Earth and lower the planet’s temperatures. The practice has not been tested at any large scale, and scientists have raised a variety of concerns about its ethics and potential unintended side effects.

Yet Hansen believes scientists and activists “should raise concerns about the safety and ethics of NOT doing SRM,” he said by email.

Climate change, caused by human greenhouse gas emissions, is in itself a form of planetary geoengineering, he added.

“My suggestion is to reduce human geoengineering of the planet,” he said.

Yet some scientists say the new paper’s findings — again — are overblown.

The paper “adds very little to the literature,” said Piers Forster, director of the Priestly International Centre for Climate at Leeds University in the U.K. and a lead chapter author of the IPCC’s latest assessment report, in an email to E&E News.

It presents high-end estimates of climate sensitivity based on ancient climate records from the Earth’s past — but those findings aren’t necessarily new, he said. Forster also suggested that some of the methods the new paper used to arrive at those high estimates were “quite subjective and not justified by observations, model studies or literature.”

Forster also took issue with the new paper’s treatment of previous climate sensitivity estimates, including the widely cited 2020 study, which the authors suggested were far too low. The 2020 study presented a careful analysis, using multiple lines of high-quality evidence, Forster said. And yet the authors of the new paper “dismiss it, on spurious grounds.”

Michael Oppenheimer, a climate scientist and director of the Center for Policy Research on Energy and Environment at Princeton University, said the uncertainties around the effects of declining aerosols were important to pay attention to. And he suggested that the new paper’s climate sensitivity estimates were possible.

But added that he regards them as “a worst-worst-case” scenario.

“I think it’s perfectly legitimate to have a worst-worst-case out there,” he added. “They help people think about what the boundaries of the possible are, and they are necessary for risk management against the climate problem.”

But there are still so many uncertainties about the kinds of feedback factors affecting the Earth’s climate sensitivity, he said, that “you can’t really nail it down with the kind of precision that [Hansen’s] provided.”

But Hansen says the new paper’s lines of evidence are based on the most up-to-date research on the Earth’s ancient history.

“[T]here is no basis whatever for the claim that our results are ‘unlikely,’” he said by email. “It is the IPCC sensitivity that is unlikely, less than 1 percent chance of being right, as we show quantitatively in our (peer-reviewed) paper.”

Hansen and 'scientific reticence'

Hansen has been into the deep end of climate debates for much of his career.

In 1988, at the time of his Senate testimony, scientists were still discussing whether the fingerprint of human-caused global warming could yet be detected above the “noise” of the Earth’s natural climate variations.

“When I first got into this, and when Jim and I were testifying, we were arguing about whether there's a global signal,” said Oppenheimer, the Princeton scientist, who testified alongside Hansen in 1988. “All the information we had was about global mean temperature, global mean sea level. We couldn’t talk in the language of things that people cared about.”

But even with the limitations of climate science at the time, the scientists warned the world of the dangers to come.

Hansen has co-authored dozens of papers on climate change in the years since, many of which have been highly regarded by the scientific community.

“Over time, he’s got a pretty damn good track record of turning out to be right about things that other people thought differently about,” Oppenheimer said.

Forster, the Leeds University scientist, agreed that “some of Hansen’s papers are brilliant and his work and deeds helped establish this IPCC in the first place.”

But he added that he still thought the new paper misses the mark.

The reception is similar to a major paper Hansen published in 2016, widely known as the “Ice Melt” paper.

The Ice Melt paper, published in the journal Atmospheric Chemistry and Physics , provided a grim, sweeping vision of the Earth’s climate future, focused on the consequences of the melting Greenland and Antarctic ice sheets. Drawing largely on ancient climate data — similar to the new paper — it warned of rapid melting and sea-level rise on the order of several meters within the next century.

It also suggested that the rapid influx of cold, fresh meltwater into the sea could affect ocean circulation patterns and even cause a giant Atlantic current to shut down. That’s a controversial prediction deemed unlikely by the IPCC , one that would have severe impacts on global weather and climate patterns if it actually happened.

The paper received mixed reactions from other climate scientists upon publication. Some praised the paper, while many suggested the findings were unrealistic.

Another 2016 paper , published by a different group of scientists, later found that the likelihood of an Atlantic current shutdown was relatively small and suggested that Hansen’s paper relied on “unrealistic assumptions.”

In his new paper, Hansen referred to that study as an “indictment” of Ice Melt. He also noted that the IPCC’s latest assessment report did not include Ice Melt’s predictions, an omission he likened in the new paper to a form of censorship.

“Science usually acknowledges alternative views and grants ultimate authority to nature,” the new paper states. “In the opinion of our first author (Hansen), IPCC does not want its authority challenged and is comfortable with gradualism. Caution has merits, but the delayed response and amplifying feedbacks of climate make excessive reticence a danger.”

Responding to critiques of his new paper, Hansen again suggested that “scientific reticence” — or a kind of resistance to new findings — is at play. He pointed to a 1961 paper by sociologist Bernard Barber suggesting that scientists themselves can be resistant to scientific discovery.

Claims that his new findings are unrealistic, Hansen said, are “a perfect example of the category of scientific reticence that Barber describes as ‘resistance to discovery.’ It takes a long time for new results to sink into the community.”

Resistance to scientific findings is nothing new to Hansen. His 1988 testimony initially shook the political establishment — yet decades later, global climate action is still proceeding too slowly to meet the Paris climate targets.

When he first testified to Congress in the 1980s, Oppenheimer said, he expected that world governments would have started meaningful emissions reduction programs by the year 2000 or so.

“We didn’t get ahead of the impacts,” he said. “And that’s probably because people weren't willing to support strong governmental action in most countries … until they were getting clobbered by unusual and highly damaging, and in some cases unprecedented, climate events.”

He regards the current state of global climate action now with a mix of skepticism and optimism.

“We’re in the process of muddling through — we’re in a period where climate change is gonna be painful for a while, it’s gonna hurt a lot of people in a lot of places, but we can get out the other side,” he said. “I think we can get there. But will we?”

Hansen echoed his sentiments in starker terms.

He wrote that he’s been surprised by “the increase of anti-science no-nothing thinking in our politics.”

“That's why I focus on young people,” he added. “They need to understand the situation and take control.”

Global Warming: Carbon Dioxide and the Greenhouse Effect

FRONTLINE/NOVA, WGBH Educational Foundation, Teachers' Domain

This video segment demonstrates carbon dioxide's role in the greenhouse effect and explains how increasing concentrations of C02 in the atmosphere may be contributing to global warming. Video includes an unusual demonstration of C02's heat-absorbing properties, using infrared film, a researcher's face, and a stream of C02 between them.

Notes from our reviewers

The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials .

Teaching Tips This short video should be used to clarify the role of carbon dioxide in absorbing infrared energy re-radiated from Earth's surface. It will enhance student understanding of the greenhouse effect. The teacher will need to prepare to lead discussion following the video, using the essay and links provided.
About the Science Video includes a simple and effective demonstration of how carbon dioxide absorbs infrared radiation -- an idea often presented poorly in the usual discussions of the greenhouse gas effect. Comments from expert scientist: Scientific strengths: Great, unique experiment to show how greenhouse gases work. - background essay is a great summary of how photosynthesis works, how humans are adding extra carbon into the atmosphere, and how greenhouse gas molecules trap the heat.
About the Pedagogy This resource includes a background essay, simple discussion questions, and links to national and state standards. The background essay discusses the sources and sinks of carbon dioxide and the idea that some of the carbon dioxide emitted by human activities is unaccounted for. Later work [http://www.nature.com/climate/2007/0708/full/climate.2007.35.html] argued that this missing carbon sink is in the greater-than-expected role of tropical forests.
Technical Details/Ease of Use The online version of the video is not of sufficient resolution for projection. The downloadable version will work better.

How Do We Reduce Greenhouse Gases?

To stop climate change , we need to stop the amount of greenhouse gases, like carbon dioxide, from increasing. For the past 150 years, burning fossil fuels and cutting down forests, which naturally pull carbon dioxide out of the air, has caused greenhouse gas levels to increase. There are two main ways to stop the amount of greenhouse gases from increasing: we can stop adding them to the air, and we can increase the Earth’s ability to pull them out of the air.

This is called climate mitigation . There is not one single way to mitigate climate change. Instead, we will have to piece together many different solutions to stop the climate from warming. Below are descriptions of the main methods that we can use.

Many of these solutions are already being implemented in places around the world. Some can be tackled by individuals, such as using less energy, riding a bike instead of driving, driving an electric car, and switching to renewable energy. Other actions to mitigate climate change involve communities, regions, or nations working together to make changes, such as switching power plants from burning coal or gas to renewable energy and growing public transit.

Use less electricity.

Taking steps to use less electricity, especially when it comes from burning coal or gas, can take a big bite out of greenhouse gas emissions. Worldwide, electricity use is responsible for a quarter of all emissions.

Some steps that you can take to use less electricity are simple and save money, like replacing incandescent light bulbs with LED bulbs that use less electricity, adding insulation to your home, and setting the thermostat lower in the winter and higher in the summer, especially when no one is home. There are also new technologies that help keep buildings energy efficient, such as glass that reflects heat, low-flow water fixtures, smart thermostats, and new air conditioning technology with refrigerants that don’t cause warming. In urban and suburban environments, green or cool roofs can limit the amount of heat that gets into buildings during hot days and help decrease the urban heat island effect .

This is an image of the roof of a home that is covered in planted vegetation, which makes it a green roof.

Green roof on the Walter Reed Community Center in Arlington, VA, US Credit: Arlington County on Flickr/CC BY-SA 2.0

Generate electricity without emissions.

Renewable energy sources include solar energy, geothermal energy, wind turbines, ocean wave and tidal energy, waste and biomass energy, and hydropower. Because they do not burn fossil fuels, these renewable energy sources do not release greenhouse gases into the atmosphere as they generate electricity. Nuclear energy also creates no greenhouse gas emissions, so it can be thought of as a solution to climate change. However, it does generate radioactive waste that needs long-term, secure storage.

Today, the amount of electricity that comes from renewable energy is growing. A few countries, such as Iceland and Costa Rica, now get nearly all of their electricity from renewable energy. In many other countries, the percentage of electricity from renewable sources is currently small (5 - 10%) but growing.

This is an image of several offshore wind turbines, with an ocean horizon.

Wind turbines can be on land or in the ocean, where high winds are common. Credit: Nicholas Doherty on Unsplash

Shrink the footprint of food.

Today, about a fifth of global carbon emissions come from raising farm animals for meat. For example, as cattle digest food they burp, releasing methane, a powerful greenhouse gas, and their manure releases the greenhouse gases carbon dioxide and nitrous oxide. And forests, which take carbon dioxide out of the air, are often cut down so that cattle have space to graze.

Eating a diet that is mostly or entirely plant-based (such as vegetables, bread, rice, and beans) lowers emissions. According to the Drawdown Project , if half the population worldwide adopts a plant-rich diet by 2050, 65 gigatons of carbon dioxide would be kept out of the atmosphere over about 30 years. (For a sense of scale, 65 gigatons of carbon dioxide is nearly two-years-worth of recent emissions from fossil fuels and industry.) Reducing food waste can make an even larger impact, saving about 90 gigatons of carbon dioxide from the atmosphere over 30 years.

This is an image of tomatoes on the vine, chick peas, sliced avocados, carrots, and onions.

Eating a plant-rich diet lowers greenhouse gas emissions. Credit: Victoria Shes on Unsplash

Travel without making greenhouse gases.

Most of the ways we have to get from place to place currently rely on fossil fuels: gasoline for vehicles and jet fuel for planes. Burning fossil fuels for transportation adds up to 14% of global greenhouse gas emissions worldwide. We can reduce emissions by shifting to alternative technologies that either don’t need gasoline (like bicycles and electric cars) or don’t need as much (like hybrid cars). Using public transportation, carpooling, biking, and walking leads to fewer vehicles on the road and less greenhouse gases in the atmosphere. Cities and towns can make it easier for people to lower greenhouse gas emissions by adding bus routes, bike paths, and sidewalks.

This is an image of an electric bike parked outside alongside a waterway.

Electric bicycles can be a way to get around without burning gasoline. Credit: Karlis Dambrans/CC BY 2.0

Reduce household waste.

Waste we put in landfills releases greenhouse gases. Almost half the gas released by landfill waste is methane, which is an especially potent greenhouse gas. Landfills are, in fact, the third largest source of methane emissions in the U.S., behind natural gas/petroleum use and animals raised for food production (and their manure). In the U.S., each member of a household produces an average of 2 kg (4.4 lbs) of trash per day. That's 726 kg (1660 lbs) of trash per person per year! Conscious choices, including avoiding unnecessary purchases, buying secondhand, eliminating reliance on single-use containers, switching to reusable bags, bottles, and beverage cups, reducing paper subscriptions and mail in favor of digital options, recycling, and composting, can all help reduce household waste.

Reduce emissions from industry.

Manufacturing, mining for raw materials, and dealing with the waste all take energy. Most of the products that we buy — everything from phones and TVs to clothing and shoes — are created in factories, which produce up to about 20% of the greenhouse gases emitted worldwide.

There are ways to decrease emissions from manufacturing. Using materials that aren’t made from fossil fuels and don’t release greenhouse gases is a good start. For example, cement releases carbon dioxide as it hardens, but there are alternative products that don’t create greenhouse gases. Similarly, bioplastics made from plants are an alternative to plastics that come from fossil fuels. Companies can also use renewable energy sources to power factories and ship the products that they create in fuel-saving cargo ships.

Take carbon dioxide out of the air.

Along with reducing the amount of carbon dioxide that we add to the air, we can also take action to increase the amount of carbon dioxide we take out of the air. The places where carbon dioxide is pulled out of the air are called carbon sinks. For example, planting trees, bamboo, and other plants increases the number of carbon sinks. Conserving forests, grasslands, peatlands, and wetlands, where carbon is held in plants and soils, protects existing carbon sinks. Farming methods such as planting cover crops and crop rotation keep soils healthy so that they are effective carbon sinks. There are also carbon dioxide removal technologies, which may be able to pull large amounts of greenhouse gases out of the atmosphere.

This is an image of a stand of tall trees in a forest, with sunlight filtering through the branches.

As the trees and other plants in a forest use sunlight to create the food they need, they are also pulling carbon dioxide out of the air. Credit: B NW on Unsplash

Solving Climate Change
Why Earth Is Warming
The Greenhouse Effect
What's Your Carbon Footprint?
Classroom Activity: Mitigation or Adaptation?
Classroom Activity: Solving the Carbon Dioxide Problem
Stabilization Wedges (Activity and Resources)

A person carrying a red sun brolly walks through a solar panel farm in France.

The race to zero emissions, and why the world depends on it

Facebook Twitter Print Email

A host of countries have recently announced major commitments to significantly cut their carbon emissions, promising to reach "net zero" in the coming years. The term is becoming a global rallying cry, frequently cited as a necessary step to successfully beat back climate change, and the devastation it is causing.

What is net zero and why is it important?

Put simply, net zero means we are not adding new emissions to the atmosphere. Emissions will continue, but will be balanced by absorbing an equivalent amount from the atmosphere.

Practically every country has joined the Paris Agreement on climate change, which calls for keeping the global temperature to 1.5°C above pre-industrial era levels. If we continue to pump out the emissions that cause climate change, however, temperatures will continue to rise well beyond 1.5, to levels that threaten the lives and livelihoods of people everywhere.

This is why a growing number of countries are making commitments to achieve carbon neutrality, or "net zero" emissions within the next few decades. It’s a big task, requiring ambitious actions starting right now.

Net zero by 2050 is the goal. But countries also need to demonstrate how they will get there. Efforts to reach net-zero must be complemented with adaptation and resilience measures, and the mobilization of climate financing for developing countries.

Clean energy, like wind power, is a key element in reaching net zero emissions. is wind farm in Montenegro.

So how can the world move toward net zero?

The good news is that the technology exists to reach net zero – and it is affordable.

A key element is powering economies with clean energy, replacing polluting coal - and gas and oil-fired power stations - with renewable energy sources, such as wind or solar farms. This would dramatically reduce carbon emissions. Plus, renewable energy is now not only cleaner, but often cheaper than fossil fuels.

A wholesale switch to electric transport, powered by renewable energy, would also play a huge role in lowering emissions, with the added bonus of slashing air pollution in the world’s major cities. Electric vehicles are rapidly becoming cheaper and more efficient, and many countries, including those committed to net zero, have proposed plans to phase out the sale of fossil-fuel powered cars.

Other harmful emissions come from agriculture (livestock produce significant levels of methane, a greenhouse gas). These could be reduced drastically if we eat less meat and more plant-based foods. Here again, the signs are promising, such as the rising popularity of "plant-based meats" now being sold in major international fast-food chains.

An electric hybrid vehicle at a charging station in Germany.

What will happen to remaining emissions?

Reducing emissions is extremely important. To get to net zero, we also need to find ways to remove carbon from the atmosphere. Here again, solutions are at hand. The most important have existed in nature for thousands of years.

These "nature-based solutions" include forests, peatbogs, mangroves, soil and even underground seaweed forests , which are all highly efficient at absorbing carbon. This is why huge efforts are being made around the world to save forests, plant trees, and rehabilitate peat and mangrove areas, as well as to improve farming techniques.

Who is responsible for getting to net zero?

We are all responsible as individuals, in terms of changing our habits and living in a way which is more sustainable, and which does less harm to the planet, making the kind of lifestyle changes which are highlighted in the UN’s Act Now campaign.

The private sector also needs to get in on the act and it is doing so through the UN Global Compact , which helps businesses to align with the UN’s environmental and societal goals.

It’s clear, however, that the main driving force for change will be made at a national government level, such as through legislation and regulations to reduce emissions.

Many governments are now moving in the right direction. By early 2021, countries representing more than 65 per cent of global carbon dioxide emissions and more than 70 per cent of the world economy, will have made ambitious commitments to carbon neutrality.　

The European Union, Japan and the Republic of Korea, together with more than 110 other countries, have pledged carbon neutrality by 2050; China says it will do so before 2060.

Some climate facts:

The earth is now 1.1°C warmer than it was at the start of the industrial revolution. We are not on track to meet agreed targets in the 2015 Paris Agreement on climate change , which stipulated keeping global temperature increase well below 2 °C or at 1.5 °C above pre-industrial levels.

2010-2019 is the warmest decade on record. On the current path of carbon dioxide emissions, the global temperature is expected to increase by 3 to 5 degrees Celsius by the end of century.

To avoid the worst of warming (maximum 1.5°C rise), the world will need to decrease fossil fuel production by roughly 6 per cent per year between 2020 and 2030. Countries are instead planning and projecting an average annual increase of 2 per cent.

Climate action is not a budget buster or economy-wrecker: In fact, shifting to a green economy will add jobs. It could yield a direct economic gain of US$26 trillion through to 2030 compared with business-as-usual. And this is likely to be a conservative estimate.

Restoring natural habitats as pictured here in Cuba will help to slow down climate change

Are these commitments any more than just political statements?

These commitments are important signals of good intentions to reach the goal, but must be backed by rapid and ambitious action. One important step is to provide detailed plans for action in nationally determined contributions or NDCs. These define targets and actions to reduce emissions within the next 5 to 10 years. They are critical to guide the right investments and attract enough finance.

So far, 186 parties to the Paris Agreement have developed NDCs. This year, they are expected to submit new or updated plans demonstrating higher ambition and action. Click here to see the NDC registry .

Is net zero realistic?

Yes! Especially if every country, city, financial institution and company adopts realistic plans for transitioning to net zero emissions by 2050.

The COVID-19 pandemic recovery could be an important and positive turning point. When economic stimulus packages kick in, there will be a genuine opportunity to promote renewable energy investments, smart buildings, green and public transport, and a whole range of other interventions that will help to slow climate change.

But not all countries are in the same position to affect change, are they?

That’s absolutely true. Major emitters, such as the G20 countries, which generate 80 per cent of carbon emissions, in particular, need to significantly increase their present levels of ambition and action.

Also, keep in mind that far greater efforts are needed to build resilience in vulnerable countries and for the most vulnerable people; they do the least to cause

climate change but bear the worst impacts. Resilience and adaptation action do not get the funding they need, however.

Even as they pursue net zero, developed countries must deliver on their commitment to provide $100 billion dollars a year for mitigation, adaptation and resilience in developing countries.

National governments are the main drivers of change to reduce harmful emissions.

What is the UN doing promote climate action?

It supports a broader process of global consensus on climate goals through the Paris Agreement and the 2030 Agenda for Sustainable Development .

It is a leading source of scientific findings and research on climate change.

Within developing countries, it assists governments with the practicalities of establishing and monitoring NDCs, and taking measures to adapt to climate change, such as by reducing disaster risks and establishing climate-smart agriculture.

climate change

Search the United Nations

What Is Climate Change
Myth Busters
Renewable Energy
Finance & Justice
Initiatives
Sustainable Development Goals
Paris Agreement
Climate Ambition Summit 2023
Climate Conferences
Press Material
Communications Tips

What Is Climate Change?

Climate change refers to long-term shifts in temperatures and weather patterns. Such shifts can be natural, due to changes in the sun’s activity or large volcanic eruptions. But since the 1800s, human activities have been the main driver of climate change , primarily due to the burning of fossil fuels like coal, oil and gas.

Burning fossil fuels generates greenhouse gas emissions that act like a blanket wrapped around the Earth, trapping the sun’s heat and raising temperatures.

The main greenhouse gases that are causing climate change include carbon dioxide and methane. These come from using gasoline for driving a car or coal for heating a building, for example. Clearing land and cutting down forests can also release carbon dioxide. Agriculture, oil and gas operations are major sources of methane emissions. Energy, industry, transport, buildings, agriculture and land use are among the main sectors causing greenhouse gases.

Illustration reads: $90 Trillion for infrastructure by 2030

Humans are responsible for global warming

Climate scientists have showed that humans are responsible for virtually all global heating over the last 200 years. Human activities like the ones mentioned above are causing greenhouse gases that are warming the world faster than at any time in at least the last two thousand years.

The average temperature of the Earth’s surface is now about 1.1°C warmer than it was in the late 1800s (before the industrial revolution) and warmer than at any time in the last 100,000 years. The last decade (2011-2020) was the warmest on record , and each of the last four decades has been warmer than any previous decade since 1850.

Many people think climate change mainly means warmer temperatures. But temperature rise is only the beginning of the story. Because the Earth is a system, where everything is connected, changes in one area can influence changes in all others.

The consequences of climate change now include, among others, intense droughts, water scarcity, severe fires, rising sea levels, flooding, melting polar ice, catastrophic storms and declining biodiversity.

People are experiencing climate change in diverse ways

Climate change can affect our health , ability to grow food, housing, safety and work. Some of us are already more vulnerable to climate impacts, such as people living in small island nations and other developing countries. Conditions like sea-level rise and saltwater intrusion have advanced to the point where whole communities have had to relocate, and protracted droughts are putting people at risk of famine. In the future, the number of people displaced by weather-related events is expected to rise.

Every increase in global warming matters

In a series of UN reports , thousands of scientists and government reviewers agreed that limiting global temperature rise to no more than 1.5°C would help us avoid the worst climate impacts and maintain a livable climate. Yet policies currently in place point to a 3°C temperature rise by the end of the century.

The emissions that cause climate change come from every part of the world and affect everyone, but some countries produce much more than others .The seven biggest emitters alone (China, the United States of America, India, the European Union, Indonesia, the Russian Federation, and Brazil) accounted for about half of all global greenhouse gas emissions in 2020.

Everyone must take climate action, but people and countries creating more of the problem have a greater responsibility to act first.

Photocomposition: an image of the world globe looking worried to a thermometer with raising temperatures

We face a huge challenge but already know many solutions

Many climate change solutions can deliver economic benefits while improving our lives and protecting the environment. We also have global frameworks and agreements to guide progress, such as the Sustainable Development Goals , the UN Framework Convention on Climate Change and the Paris Agreement . Three broad categories of action are: cutting emissions, adapting to climate impacts and financing required adjustments.

Switching energy systems from fossil fuels to renewables like solar or wind will reduce the emissions driving climate change. But we have to act now. While a growing number of countries is committing to net zero emissions by 2050, emissions must be cut in half by 2030 to keep warming below 1.5°C. Achieving this means huge declines in the use of coal, oil and gas: over two-thirds of today’s proven reserves of fossil fuels need to be kept in the ground by 2050 in order to prevent catastrophic levels of climate change.

Adapting to climate consequences protects people, homes, businesses, livelihoods, infrastructure and natural ecosystems. It covers current impacts and those likely in the future. Adaptation will be required everywhere, but must be prioritized now for the most vulnerable people with the fewest resources to cope with climate hazards. The rate of return can be high. Early warning systems for disasters, for instance, save lives and property, and can deliver benefits up to 10 times the initial cost.

We can pay the bill now, or pay dearly in the future

Climate action requires significant financial investments by governments and businesses. But climate inaction is vastly more expensive. One critical step is for industrialized countries to fulfil their commitment to provide $100 billion a year to developing countries so they can adapt and move towards greener economies.

To get familiar with some of the more technical terms used in connection with climate change, consult the Climate Dictionary .

Learn more about…

photocomposition: two hands, each one holding a megaphone

The facts on climate and energy

Climate change is a hot topic – with myths and falsehoods circulating widely. Find some essential facts here .

The science

See the latest climate reports from the United Nations as well as climate action facts .

Causes and Effects

Fossil fuels are by far the largest contributor to the greenhouse gas emissions that cause climate change, which poses many risks to all forms of life on Earth. Learn more .

From the Secretary-General

Read the UN Chief’s latest statements on climate action.

What is net zero? Why is it important? Our net-zero page explains why we need steep emissions cuts now and what efforts are underway.

Renewable energy – powering a safer future

What is renewable energy and why does it matter? Learn more about why the shift to renewables is our only hope for a brighter and safer world.

How will the world foot the bill? We explain the issues and the value of financing climate action.

What is climate adaptation? Why is it so important for every country? Find out how we can protect lives and livelihoods as the climate changes.

Climate Issues

Learn more about how climate change impacts are felt across different sectors and ecosystems.

Why women are key to climate action

Women and girls are on the frontlines of the climate crisis and uniquely situated to drive action. Find out why it’s time to invest in women.

Facts and figures

What is climate change?
Causes and effects
Myth busters

Cutting emissions

Explaining net zero
High-level expert group on net zero
Checklists for credibility of net-zero pledges
Greenwashing
What you can do

Clean energy

Renewable energy – key to a safer future
What is renewable energy
Five ways to speed up the energy transition
Why invest in renewable energy
Clean energy stories
A just transition

Adapting to climate change

Climate adaptation
Early warnings for all
Youth voices

Financing climate action

Finance and justice
Loss and damage
$100 billion commitment
Why finance climate action
Biodiversity
Human Security

International cooperation

What are Nationally Determined Contributions
Acceleration Agenda
Climate Ambition Summit
Climate conferences (COPs)
Youth Advisory Group
Action initiatives
Secretary-General’s speeches
Press material
Fact sheets
Communications tips

Share full article

Subscriber-only Newsletter

Climate Forward

Three greenhouse gases, three all-time highs.

Why emissions hit record levels last year.

By David Gelles

The extreme weather . The melting glaciers . The weirdly warm oceans . They’re all the product of global warming, which is being driven by the release of the three most important heat-trapping gases: carbon dioxide, methane and nitrous oxide.

And according to a new study from the National Oceanic and Atmospheric Administration , emissions of those three greenhouse gases continued to surge last year to historic highs.

Global average carbon dioxide concentrations jumped last year, “extending the highest sustained rate of CO2 increases” in NOAA’s 65 years of record-keeping. Methane and nitrous oxide levels also rose sharply last year. All this despite a wave of global policy measures and economic incentives designed to wean the world off fossil fuels.

These weren’t just one-off anomalies. In each case, the rising emissions continued a long-term trend. By analyzing more than 15,000 air samples from around the world, NOAA found that the upticks in emissions last year “were in line with the steep increases observed during the past decade.”

The result has been a series of profound changes to the planet in a remarkably short amount of time. “The amount of CO2 in the atmosphere today is comparable to where it was around 4.3 million years ago during the mid-Pliocene epoch,” the NOAA report found. That was when the “sea level was about 75 feet higher than today” and “large forests occupied areas of the Arctic that are now tundra.”

Carbon dioxide

Last year, humans spewed some 36.6 billion tons of CO2 into the atmosphere, the most ever. That number may well be higher this year.

The concentration of carbon dioxide in the atmosphere is now more than 50 percent higher than it was before the industrial revolution.

It’s no secret where all this carbon dioxide is coming from. The burning of oil, coal and gas is the main source of CO2 emissions, and the use and production of fossil fuels continues to rise around the world, with the United States producing more oil and gas than ever before .

And even as the build out of renewable energy is speeding up, the appetite for fossil fuels remains strong, in part because overall energy demand is soaring .

Fossil fuels aren’t the only source of carbon dioxide. The extraordinary forest fires that have charred Canada, Europe and Chile over the past year are also adding CO2 into the atmosphere. Yet even there, the vicious cycle of human-caused climate change is easy to see: Many of those fires were made worse because of the warming that has already occurred.

For a while, it looked like methane emissions were slowing down. After a rapid rise in atmospheric methane concentration during the 1980s, levels stabilized in the late 1990s and early 2000s. Then in 2007, they started rising again, and fast.

Researchers acknowledge they don’t fully understand what accounted for the relative stability of methane output and then its renewed growth. But what is clear is that methane emissions are booming today.

Last year saw the fifth-highest ever jump in methane concentration since record keeping began, and methane levels are now more than 160 percent higher than they were before the industrial revolution, according to NOAA. Methane is a particularly potent greenhouse gas; while it breaks down faster than carbon dioxide, it is more powerful at trapping heat in the atmosphere.

The vast majority of the increased methane emissions can be traced back to humanity’s insatiable appetite. Agriculture is the biggest source of methane emissions, according to the International Energy Agency , followed closely by the burning of fossil fuels.

Nitrous oxide

While carbon dioxide and methane are the two gases most commonly associated with climate change, nitrous oxide is another potent heat-trapping gas, and is also on the rise.

N2O emissions are also linked to food. In this case, they are largely the result of nitrogen fertilizer and manure used in agriculture. Another source is aviation . Nitrous oxide levels in the atmosphere are now 25 percent higher than before the industrial revolution.

Where all that gas goes

In just a few hundred years, humans have radically altered the composition of Earth’s atmosphere, quite literally setting the planet back millions of years. Slowing down global warming, and potentially even reversing it , will require an equally herculean effort to stop emitting the three gases most responsible for climate change.

Reducing carbon dioxide emissions will require radical overhauls to our energy and transportation systems. Drawing down methane and nitrous oxide emissions will mean fundamentally overhauling how food is produced.

The changes won’t be easy. But until we figure out how to limit the release of carbon dioxide, methane and nitrous oxide, our world will keep warming.

A landmark ruling in Europe could mean more climate litigation

Europe’s top human rights court said on Tuesday that the Swiss government had violated its citizens’ human rights by not doing enough to stop climate change , a landmark ruling that experts said could bolster activists hoping to use human rights law to hold governments to account.

“I expect we’re going to see a rash of lawsuits in other European countries, because most of them have done the same thing,” said Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University. “They have failed to meet their climate goals, and failed to set climate targets that are adequate.”

It was the latest sign that the global wave of lawsuits seeking to hold companies and governments responsible for damage caused by climate change is gaining momentum.

In the United States, states, cities and counties are suing fossil fuel companies over the damages caused by climate change, and young people are suing states and the federal government over what they say was a failure to protect them from the effects of global warming.

Legal experts are watching closely to see whether the Supreme Court will take up a lawsuit that Hawaii has brought against big oil companies . Should the country’s top court intervene, it could be helpful for fossil fuel corporations, which believe they have a better chance at winning in federal court than in many state courts.

The European ruling is unlikely to affect how U.S. courts rule, according to Gerrard. “The U.S. courts traditionally pay little regard to international tribunals,” he said.

But Gerrard added that many similar concepts are involved in the European case and those making their way through the court system in the United States.

“The idea that climate change impairs fundamental rights resonates throughout the cases,” he said. “The language is different, but the underlying concepts, and the idea that the governments have a duty to act, are the same.”

Similar legal efforts are unfolding around the world. India’s Supreme Court handed down a ruling last month concluding that people’s right to be shielded from the effects of climate change falls under the articles of the country’s constitution that protect the right to equality and to life. And the Inter-American Court is also preparing to issue an advisory opinion on whether countries are legally required to protect citizens from climate change. — David Gelles and Manuela Andreoni

More climate news

Western diplomats are pressuring China to commit to funding efforts by developing countries to tackle climate change, Politico reports .

Refrigerants that are several thousand times more potent than carbon dioxide in warming the planet are being smuggled into Europe, according to a report reviewed by Reuters .

Warren Buffett made a fortune investing in utilities, but increasing wildfires are making him rethink his strategy, The Wall Street Journal reports .

Six hundred years ago, Native North Americans changed their way of life to adapt to a changing climate, The Atlantic reports.

Because of an editing error, an earlier version of a picture caption with this newsletter misidentified a potent greenhouse gas. It is nitrous oxide, not nitrogen.

How we handle corrections

David Gelles reports on climate change and leads The Times’s Climate Forward newsletter and events series . More about David Gelles

Learn More About Climate Change

Have questions about climate change? Our F.A.Q. will tackle your climate questions, big and small .

“Buying Time,” a new series from The New York Times, looks at the risky ways humans are starting to manipulate nature to fight climate change.

Big brands like Procter & Gamble and Nestlé say a new generation of recycling plants will help them meet environmental goals, but the technology is struggling to deliver .

The Italian energy giant Eni sees future profits from collecting carbon dioxide and pumping it into natural gas fields that have been exhausted.

New satellite-based research reveals how land along the East Coast is slumping into the ocean, compounding the danger from global sea level rise . A major culprit: the overpumping of groundwater.

Did you know the ♻ symbol doesn’t mean something is actually recyclable ? Read on about how we got here, and what can be done.

An official website of the United States government

Here’s how you know

Official websites use .gov A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS A lock ( Lock A locked padlock ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

JavaScript appears to be disabled on this computer. Please click here to see any active alerts .

Global Greenhouse Gas Overview

On This Page:

Global Emissions and Removals by Gas

Global emissions by economic sector, trends in global emissions, emissions by country.

At the global scale, the key greenhouse gases emitted by human activities are:

Carbon dioxide (CO 2 ) : Fossil fuel use is the primary source of CO 2 . CO 2 can also be emitted from the landscape through deforestation, land clearance for agriculture or development, and degradation of soils. Likewise, land management can also remove additional CO 2 from the atmosphere through reforestation, improvement of soil health, and other activities.
Methane (CH 4 ) : Agricultural activities, waste management, energy production and use, and biomass burning all contribute to CH 4 emissions.
Nitrous oxide (N 2 O) : Agricultural activities, such as fertilizer use, are the primary source of N 2 O emissions. Chemical production and fossil fuel combustion also generates N 2 O.
Fluorinated gases (F-gases) : Industrial processes, refrigeration, and the use of a variety of consumer products contribute to emissions of F-gases, which include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF 6 ).

Additional compounds in the atmosphere including solid and liquid aerosol and other greenhouse gases, such as water vapor and ground-level ozone can also impact the climate. Learn more about these compounds and climate change on our Basics of Climate Change page .

Source: Data from IPCC (2022); Based on global emissions from 2019, details on the sectors and individual contributing sources can be found in the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Mitigation of Climate Change, Chapter 2.

Global greenhouse gas emissions can also be broken down by the economic activities that lead to their atmospheric release. [1]

Electricity and Heat Production (34% of 2019 global greenhouse gas emissions): The burning of coal, natural gas, and oil for electricity and heat is the largest single source of global greenhouse gas emissions.
Industry (24% of 2019 global greenhouse gas emissions): Greenhouse gas emissions from industry primarily involve fossil fuels burned on site at facilities for energy. This sector also includes emissions from chemical, metallurgical, and mineral transformation processes not associated with energy consumption and emissions from waste management activities. (Note: Emissions from industrial electricity use are excluded and are instead covered in the Electricity and Heat Production sector.)
Agriculture, Forestry, and Other Land Use (22% of 2019 global greenhouse gas emissions): Greenhouse gas emissions from this sector come mostly from agriculture (cultivation of crops and livestock) and deforestation. This estimate does not include the CO 2 that ecosystems remove from the atmosphere by sequestering carbon (e.g. in biomass, soils). [2]
Transportation (15% of 2019 global greenhouse gas emissions): Greenhouse gas emissions from this sector primarily involve fossil fuels burned for road, rail, air, and marine transportation. Almost all (95%) of the world's transportation energy comes from petroleum-based fuels, largely gasoline and diesel. [3]
Buildings (6% of 2019 global greenhouse gas emissions): Greenhouse gas emissions from this sector arise from onsite energy generation and burning fuels for heat in buildings or cooking in homes. Note: Emissions from this sector are 16% when electricity use in buildings is included in this sector instead of the Energy sector.

Note on emissions sector categories.

Emissions of non-CO 2 greenhouse gases (CH 4 , N 2 O, and F-gases) have also increased significantly since 1850.

Globally, greenhouse gas emissions continued to rise across all sectors and subsectors, most rapidly in the transport and industry sectors.
While the trend in emissions continues to rise, annual greenhouse gas growth by sector slowed in 2010 to 2019, compared to 2000 to 2009, for energy and industry, however remained roughly stable for transport.
The trend for for AFOLU remains more uncertain, due to the multitude of drivers that affect emissions and removals for land use, land-use change and forestry.
rising demand for construction materials and manufactured products,
increasing floor space per capita,
increasing building energy use,
travel distances, and vehicle size and weight.

To learn more about past and projected global emissions of non-CO 2 gases, please see the EPA report, Global Non-CO 2 Greenhouse Gas Emission Projections & Mitigation Potential: 2015-2050 . For further insights into mitigation strategies specifically within the U.S. forestry and agriculture sectors, refer to the latest Climate Economic Analysis report on Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture .

In 2020, the top ten greenhouse gas emitters were China, the United States, India, the European Union, Russia, Indonesia, Brazil, Japan, Iran, and Canada. These data include CO 2 , CH 4 , N 2 O, and fluorinated gas emissions from energy, agriculture, forestry and land use change, industry, and waste. Together, these top ten countries represent approximately 67% of total greenhouse gas emissions in 2020.

Emissions and sinks related to changes in land use are not included in these estimates. However, changes in land use can be important: estimates indicate that net global greenhouse gas emissions from agriculture, forestry, and other land use were approximately 12 billion metric tons of CO 2 equivalent, [2] or about 21% of total global greenhouse gas emissions. [3] In areas such as the United States and Europe, changes in land use associated with human activities have the net effect of absorbing CO 2 , partially offsetting the emissions from deforestation in other regions.

EPA resources

Greenhouse Gas Emissions
Sources of Greenhouse Gas Emissions (in the United States)
Non-CO 2 Greenhouse Gases: Emissions and Trends
Capacity Building for National GHG Inventories

Other resources

UNFCCC GHG Data Interface
European Commission Emission Database for Global Atmospheric Research
World Development Indicators
Climate Watch
Carbon Dioxide and Information Analysis Center (CDIAC)
Greenhouse Gas Emissions from Energy Data Explorer (IEA)

1. IPCC (2022), Emissions Trends and Drivers. In IPCC, 2022: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.004

2. Jia, G., E. Shevliakova, P. Artaxo, N. De Noblet-Ducoudré, R. Houghton, J. House, K. Kitajima, C. Lennard, A. Popp, A. Sirin, R. Sukumar, L. Verchot, 2019: Land–climate interactions . In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems [P.R. Shukla, J. Skea, E. Calvo Buendia, V. Masson-Delmotte, H.-O. Pörtner, D.C. Roberts, P. Zhai, R. Slade, S. Connors, R. van Diemen, M. Ferrat, E. Haughey, S. Luz, S. Neogi, M. Pathak, J. Petzold, J. Portugal Pereira, P. Vyas, E. Huntley, K. Kissick, M, Belkacemi, J. Malley, (eds.)]. https://doi.org/10.1017/9781009157988.004

3. U.S. Energy Information Administration, Annual Energy Outlook 2021 , (February 2021), www.eia.gov/aeo

Note on emissions sector categories:

The global emission estimates described on this page are from the Intergovernmental Panel (IPCC) on Climate Change's Fifth Assessment Report. In this report, some of the sector categories are defined differently from how they are defined in the Sources of Greenhouse Gas Emissions page on this website. Transportation, Industry, Agriculture, and Land Use and Forestry are four global emission sectors that roughly correspond to the U.S. sectors. Energy Supply, Commercial and Residential Buildings, and Waste and Wastewater are categorized slightly differently. For example, the IPCC's Energy Supply sector for global emissions encompasses the burning of fossil fuel for heat and energy across all sectors. In contrast, the U.S. Sources discussion tracks emissions from the electric power separately and attributes on-site emissions for heat and power to their respective sectors (i.e., emissions from gas or oil burned in furnaces for heating buildings are assigned to the residential and commercial sector). The IPCC has defined Waste and Wastewater as a separate sector, while in the Sources of Greenhouse Gas Emissions page, waste and wastewater emissions are attributed to the Commercial and Residential sector.

GHG Emissions and Removals Home
Overview of Greenhouse Gases
Sources of GHG Emissions and Removals
Global Emissions and Removals
National Emissions and Removals
State and Tribal GHG Data and Resources
Facility-Level Emissions
Gridded Methane Emissions
Carbon Footprint Calculator
GHG Equivalencies Calculator
Capacity Building for GHG Inventories

Globalization and Greenhouse Gas Emissions: Evidence from the United States

The US has been a global leader in regulating local air pollution and a global laggard in regulating greenhouse gases (GHGs). For decades, critics of US policy have expressed fears that stringent US regulations on local air pollution would lead to pollution havens overseas. Prior research, suggests that has not happened. But what about the converse fear? Are the less stringent US climate regulations causing the US to become a pollution haven for other countries’ GHG-intensive industries? We provide a decomposition of US manufacturing GHG emissions and find no evidence of offshoring either to or from the United States since 1990.

This is a draft chapter for the forthcoming book, Handbook on Trade Policy and Climate Change, Edward Elgar Publishing, edited by Michael Jakob. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.

Arik Levinson has been receiving compensation for serving on the EPA Science Advisory Board's Economic Guidelines Review Panel.

MARC RIS BibTeΧ

Download Citation Data

More from NBER

In addition to working papers , the NBER disseminates affiliates’ latest findings through a range of free periodicals — the NBER Reporter , the NBER Digest , the Bulletin on Retirement and Disability , the Bulletin on Health , and the Bulletin on Entrepreneurship — as well as online conference reports , video lectures , and interviews .

15th Annual Feldstein Lecture, Mario Draghi, "The Next Flight of the Bumblebee: The Path to Common Fiscal Policy in the Eurozone cover slide

Greenhouse gases are rocketing to record levels – highest in at least 800,000 years

The cause of global warming shows no sign of slowing down: Levels of the three most significant human-caused greenhouse gases – carbon dioxide (CO2), methane and nitrous oxide – continued their steady climb last year, federal scientists reported this month.

In fact, because of the burning of fossil fuels such as coal, oil and natural gas, those three greenhouse gases in our atmosphere have risen to levels not seen in at least 800,000 years − and potentially far longer, perhaps millions of years, the National Oceanic and Atmospheric Administration, said.

"We still have a lot of work to do to make meaningful progress in reducing the amount of greenhouse gases accumulating in the atmosphere," said Vanda Grubišić, director of NOAA's Global Monitoring Laboratory, which released the report.

Carbon dioxide increased in 2023

The global surface concentration of CO2, averaged across all of 2023, was 419.3 parts per million (ppm), an increase of 2.8 ppm over the prior year. This was the 12th consecutive year CO2 increased by more than 2 ppm, extending the highest sustained rate of CO2 increases on record.

“The 2023 increase is the third-largest in the past decade, likely a result of an ongoing increase of fossil fuel CO2 emissions, coupled with increased fire emissions possibly as a result of the transition from La Niña to El Niño,” said Xin Lan, a University of Colorado Boulder atmospheric scientist who works with NOAA.

The increase in carbon dioxide also coincided with yet another unusually warm year for the planet in 2023: Data from both NASA and NOAA agreed that global average temperatures last year were the warmest on record.

March madness? It's hot, so hot in here: Warmest March on record was part of a 10-month streak

Methane, nitrous oxide also rose

Methane, which is less abundant than carbon dioxide but more potent at trapping heat in our atmosphere, rose to an average of 1922.6 parts per billion (ppb), according to NOAA. The 2023 methane increase over 2022 was 10.9 ppb. In 2023, levels of nitrous oxide, the third-most significant human-caused greenhouse gas, climbed by 1 ppb to 336.7 ppb.

“Fossil fuel pollution is warming natural systems like wetlands and permafrost," Rob Jackson, who heads the Global Carbon Project, told The Associated Press . "Those ecosystems are releasing even more greenhouse gases as they heat up. We’re caught between a rock and a charred place.”

What causes global warming?

The burning of fossil fuels such as coal, oil and gas releases greenhouse gases such as carbon dioxide and methane, which has caused the temperature of Earth's atmosphere to rise to levels that cannot be explained by natural causes, scientists say.

Carbon dioxide is called a greenhouse gas because of its ability to trap solar radiation and keep it confined to the atmosphere.

It is invisible, odorless and colorless, yet is responsible for 63% of the warming attributable to all greenhouse gases, according to NOAA's Earth System Research Laboratory in Colorado.

Atmospheric levels of carbon dioxide are now similar to where they were during the mid-Pliocene epoch, about 4.3 million years ago, NOAA said.

No sign of greenhouse gases increases slowing in 2023

April 5, 2024

Levels of the three most important human-caused greenhouse gases – carbon dioxide (CO 2 ), methane and nitrous oxide – continued their steady climb during 2023, according to NOAA scientists.

While the rise in the three heat-trapping gases recorded in the air samples collected by NOAA’s Global Monitoring Laboratory (GML) in 2023 was not quite as high as the record jumps observed in recent years, they were in line with the steep increases observed during the past decade.

“NOAA’s long-term air sampling program is essential for tracking causes of climate change and for supporting the U.S. efforts to establish an integrated national greenhouse gas measuring, monitoring and information system,” said GML Director Vanda Grubišić. “As these numbers show, we still have a lot of work to do to make meaningful progress in reducing the amount of greenhouse gases accumulating in the atmosphere.”

The global surface concentration of CO 2 , averaged across all 12 months of 2023, was 419.3 parts per million (ppm), an increase of 2.8 ppm during the year. This was the 12th consecutive year CO 2 increased by more than 2 ppm, extending the highest sustained rate of CO 2 increases during the 65-year monitoring record. Three consecutive years of CO 2 growth of 2 ppm or more had not been seen in NOAA’s monitoring records prior to 2014. Atmospheric CO 2 is now more than 50% higher than pre-industrial levels.

This graph shows the globally averaged monthly mean carbon dioxide abundance measured at the Global Monitoring Laboratory’s global network of air sampling sites since 1980. Data are still preliminary, pending recalibrations of reference gases and other quality control checks. Credit: NOAA GML

“The 2023 increase is the third-largest in the past decade, likely a result of an ongoing increase of fossil fuel CO 2 emissions, coupled with increased fire emissions possibly as a result of the transition from La Nina to El Nino,” said Xin Lan, a CIRES scientist who leads GML’s effort to synthesize data from the NOAA Global Greenhouse Gas Reference Network for tracking global greenhouse gas trends .

Atmospheric methane, less abundant than CO 2 but more potent at trapping heat in the atmosphere, rose to an average of 1922.6 parts per billion (ppb). The 2023 methane increase over 2022 was 10.9 ppb, lower than the record growth rates seen in 2020 (15.2 ppb), 2021(18 ppb) and 2022 (13.2 ppb), but still the 5th highest since renewed methane growth started in 2007. Methane levels in the atmosphere are now more than 160% higher than their pre-industrial level.

This graph shows globally-averaged, monthly mean atmospheric methane abundance determined from marine surface sites for the full NOAA time-series starting in 1983. Values for the last year are preliminary, pending recalibrations of standard gases and other quality control steps. Credit: NOAA GM

In 2023, levels of nitrous oxide, the third-most significant human-caused greenhouse gas, climbed by 1 ppb to 336.7 ppb. The two years of highest growth since 2000 occurred in 2020 (1.3 ppb) and 2021 (1.3 ppb). Increases in atmospheric nitrous oxide during recent decades are mainly from use of nitrogen fertilizer and manure from the expansion and intensification of agriculture. Nitrous oxide concentrations are 25% higher than the pre-industrial level of 270 ppb.

Taking the pulse of the planet one sample at a time NOAA’s Global Monitoring Laboratory collected more than 15,000 air samples from monitoring stations around the world in 2023 and analyzed them in its state-of-the-art laboratory in Boulder,

Colorado. Each spring, NOAA scientists release preliminary calculations of the global average levels of these three primary long-lived greenhouse gases observed during the previous year to track their abundance, determine emissions and sinks, and understand carbon cycle feedbacks.

Measurements are obtained from air samples collected from sites in NOAA’s Global Greenhouse Gas Reference Network , which includes about 53 cooperative sampling sites around the world, 20 tall tower sites, and routine aircraft operation sites from North America.

Carbon dioxide emissions remain the biggest problem

By far the most important contributor to climate change is CO 2 , which is primarily emitted by burning of fossil fuels. Human-caused CO 2 pollution increased from 10.9 billion tons per year in the 1960s – which is when the measurements at the Mauna Loa Observatory in Hawaii began – to about 36.8 billion tons per year in 2023. This sets a new record, according to the Global Carbon Project , which uses NOAA’s Global Greenhouse Gas Reference Network measurements to define the net impact of global carbon emissions and sinks.

The amount of CO 2 in the atmosphere today is comparable to where it was around 4.3 million years ago during the mid- Pliocene epoch , when sea level was about 75 feet higher than today, the average temperature was 7 degrees Fahrenheit higher than in pre-industrial times, and large forests occupied areas of the Arctic that are now tundra.

About half of the CO 2 emissions from fossil fuels to date have been absorbed at the Earth’s surface, divided roughly equally between oceans and land ecosystems, including grasslands and forests. The CO 2 absorbed by the world’s oceans contributes to ocean acidification, which is causing a fundamental change in the chemistry of the ocean, with impacts to marine life and the people who depend on them. The oceans have also absorbed an estimated 90% of the excess heat trapped in the atmosphere by greenhouse gases.

Research continues to point to microbial sources for rising methane

NOAA’s measurements show that atmospheric methane increased rapidly during the 1980s, nearly stabilized in the late-1990s and early 2000s, then resumed a rapid rise in 2007.

A 2022 study by NOAA and NASA scientists and additional NOAA research in 2023 suggests that more than 85% of the increase from 2006 to 2021 was due to increased microbial emissions generated by livestock, agriculture, human and agricultural waste, wetlands and other aquatic sources. The rest of the increase was attributed to increased fossil fuel emissions.

“In addition to the record high methane growth in 2020-2022, we also observed sharp changes in the isotope composition of the methane that indicates an even more dominant role of microbial emission increase,” said Lan. The exact causes of the recent increase in methane are not yet fully known.

NOAA scientists are investigating the possibility that climate change is causing wetlands to give off increasing methane emissions in a feedback loop.

To learn more about the Global Monitoring Laboratory’s greenhouse gas monitoring, visit: https://gml.noaa.gov/ccgg/trends/.

Media Contact: Theo Stein, [email protected] , 303-819-7409

5 science wins from the 2023 NOAA Science Report

Red autonomous glider in the shape of a surfboard with a sail is connected to a towline for deployment

Filling A Data Gap In The Tropical Pacific To Reveal Daily Air-Sea Interactions

Satellite image showing marine stratus clouds and linear "ship-track" exhaust plumes.

Scientists detail research to assess viability and risks of marine cloud brightening

How social science helps us combat climate change

Popup call to action.

A prompt with more information on your call to action.

The majority of fossil fuel companies produce more emissions after Paris Agreement than before: report

Most fossil fuel companies have produced more emissions in the seven years since the Paris Agreement was signed than the seven years before the major climate pact, a new report reveals.

It found that 80 per cent of the fossil fuel and cement emissions since the Paris Agreement have come from just 57 producers.

State-owned oil producer Saudi Aramco has produced the most carbon emissions since the Paris Agreement, making up 4.8 per cent of global emissions.

The aim of the Paris Agreement forged in 2015 is for all countries to reduce their greenhouse gas emissions to keep global warming to at least 1.5 degrees.

The report is released by UK non-for-profit think tank InfluenceMap , which focuses on climate risks and is known for its work tracking the lobbying of fossil fuel emitters.

This latest analysis is based on emissions data collected in a database called Carbon Majors that has been running since 2013.

It attributes emissions to the top 122 coal, oil, gas and cement producers and ranks them for their overall contribution to climate change. These entities account for three-quarters of global emissions.

InfluenceMap's program manager Daan Van Acker said the aim was to bring more transparency to the sources of the bulk of global emissions.

"The main objective of the database is really to be an accountability tool, holding these entities to account for the products that they've produced, which are the foremost contributor to global climate change," he said.

"It's a very limited group of companies that are such a significant portion of global emissions."

Four Australian companies are included in the database: BHP, Woodside, Santos and Whitehaven Coal. Three of them increased emissions since 2016, according to the research, however it noted that BHP had a "significant" decrease in emissions.

An upwards trending line graph showing emissions for the world's regions

Holding big polluters to account

The report traces emissions as far back as the Industrial Revolution, when humans began burning fossil fuels and emitting increasing amounts of carbon into the atmosphere.

Overall, China's national coal production has been the biggest single source of pollution, accounting for 14 per cent of global historical emissions, with the former Soviet Union coming in second.

Mr Van Acker said the research had been applied in many ways to hold companies to account, including climate litigation.

"We're seeing the data being used in legal cases, holding these fossil fuel producers to account for climate damages," he said.

The database was cited in a recent case in which a Belgian farmer was arguing that an oil and gas company was partly responsible for damage to his farm from extreme weather.

"We anticipate that that will only continue to happen more as we go forward," Mr Van Acker said.

"We're also seeing [the data] in academic research, quantifying the contribution that the emissions by these producers have made to, for example, sea level rise to forest fire risk, and so on.

"But also it can be used by investors in the companies or by campaign groups looking to pressure these companies."

The Paris Agreement also marked a change in coal emissions; while investor-owned coal companies have reduced their output since 2015, coal emissions from state-owned companies have increased.

"It's certainly an interesting issue to analyse further, what's causing that, whether it's investor pressure that has managed to somewhat drive down the production of coal among investor-owned companies," Mr Van Acker told the ABC.

The top shareholder-owned companies responsible for historical emissions are Chevon, ExxonMobil, BP, Shell, and ConocoPhillips and they have contributed 11 per cent of historical emissions.

In an initial response, Chevron Australia pointed to its latest climate report, saying the company supported the global ambitions of the Paris Agreement.

"We believe the future of energy is lower carbon […] and we aspire to reach net zero upstream emissions [Scope 1 and 2] by 2050," a spokesman said.

BHP said in a statement the company was on track to deliver its target to curb operational emissions by 30 per cent by 2030, with an "aspirational goal" to reach net zero emissions in 2050.

Shell Australia declined to comment, saying it could not verify the data and would only comment on their own emissions.

The ABC has also contacted Santos, Woodside, Whitehaven Coal, and ExxonMobil for comment.

To compile their database, the researchers use company data on their production of fossil fuels to calculate emissions, as well as industry and government data when needed.

X (formerly Twitter)

Fossil fuel phase-out deal seen as huge step forward by many as COP28 draws to a close

Man wearing traditional Emirati clothing walks past a big saying which reads #COP28

Business Enterprises
Climate Change
Environmental Policy
Environmentally Sustainable Business
Global Warming
Oil and Gas

International edition
Australia edition
Europe edition

A pump jack operates in front of a drilling rig at sunset in an oil field in Texas, US.

Just 57 companies linked to 80% of greenhouse gas emissions since 2016

Analysis reveals many big producers increased output of fossil fuels and related emissions in seven years after Paris climate deal

A mere 57 oil, gas, coal and cement producers are directly linked to 80% of the world’s global fossil CO2 emissions since the 2016 Paris climate agreement, a study has shown.

This powerful cohort of state-controlled corporations and shareholder-owned multinationals are the leading drivers of the climate crisis, according to the Carbon Majors Database , which is compiled by world-renowned researchers.

Although governments pledged in Paris to cut greenhouse gases, the analysis reveals that most mega-producers increased their output of fossil fuels and related emissions in the seven years after that climate agreement, compared with the seven years before.

In the database of 122 of the world’s biggest historical climate polluters, the researchers found that 65% of state entities and 55% of private-sector companies had scaled up production.

During this period, the biggest investor-owned contributor to emissions was ExxonMobil of the United States, which was linked to 3.6 gigatonnes of CO 2 over seven years, or 1.4% of the global total. Close behind were Shell, BP, Chevron and TotalEnergies, each of which was associated with at least 1% of global emissions.

The most striking trend, however, was the surging growth of emissions related to state and state-owned producers, particularly in the Asian coal sector.

This expansion, which has continued since, runs contrary to a stark warning by the International Energy Agency that no new oil and gas fields can be opened if the world is to stay within safe limits of global heating. Climate scientists say global temperatures are rapidly approaching the lower Paris target of 1.5C above the pre-industrial era, with potentially dire consequences for people and the rest of nature.

“It is morally reprehensible for companies to continue expanding exploration and production of carbon fuels in the face of knowledge now for decades that their products are harmful,” said Richard Heede, who established the Carbon Majors dataset in 2013. “Don’t blame consumers who have been forced to be reliant on oil and gas due to government capture by oil and gas companies.”

The Carbon Majors research has helped to change the narrative about responsibility for the climate crisis by apportioning emissions to the entities that profit from taking fossil fuels out of the ground rather than the individuals that later burn and discharge them in the form of emissions. This ongoing study has been cited in climate lawsuits and was the basis for the Guardian’s 2019 series, The Polluters , which named and shamed the 20 companies behind a third of all carbon emissions.

The database has now been updated and was relaunched on Thursday on a dedicated public access website , which is hosted by InfluenceMap.

It includes a striking comparison between long-term emissions trends dating back to 1854, and more recent developments since the 2016 Paris deal.

The historical record encompasses 122 entities linked to 72% of all the fossil fuel and cement CO 2 emissions since the start of the industrial revolution, which amounts to 1,421 gigatonnes.

In this long-term analysis, Chinese state coal production accounts for 14% of historic global C0 2 , the biggest share by far in the database. This is more than double the proportion of the former Soviet Union, which is in second place, and more than three times higher than that of Saudi Aramco, which is in third.

Then comes the big US companies – Chevron (3%) and ExxonMobil (2.8%), followed by Russian’s Gazprom and the National Iranian Oil Company. After that are two investor-owned European firms: BP and Shell (each with more than 2%) and then Coal India.

The 21st century rise of Asia becomes apparent when the historical records are compared with data from 2016-2022. In this recent period, the China coal share leaps to more than a quarter of all CO 2 emission, while Saudi Aramco goes up to nearly 5%. The top 10 in this modern era is dominated by Chinese and Russian state entities and filled out with those from India and Iran. Western capitalism does not appear until the 11th placed ExxonMobil with 1.4%, half of its historical average.

The picture may change again in the future. The United States is by far the world’s biggest oil and gas producer even if operations are fragmented among many different companies rather than one state behemoth. President Biden has granted licences to multiple new exploration projects. Gulf states are also planning to step up their output.

ExxonMobil , Chevron , BP and Shell all have net zero emissions targets, though their definitions of that goal and methods to achieve it vary. Many of the companies on the list have made some investments in renewable energy.

Daan Van Acker, program manager at InfluenceMap, said many of the entities in the Carbon Majors database were moving in the wrong direction for climate stability. “InfluenceMap’s new analysis shows that this group is not slowing down production, with most entities increasing production after the Paris agreement. This research provides a crucial link in holding these energy giants to account on the consequences of their activities.”

Heede argues that fossil fuel producers have a moral obligation to pay for the damages they have caused and exacerbated through their delaying tactics. He cites the proposal made by Mia Mottley, the prime minister of Barbados, for oil and gas companies to contribute at least 10 cents in every dollar to a loss and damage fund.

He was also encouraged by actions to hold fossil fuel firms to account. As examples, he cited the billboards that sprang up in Houston, Texas, after a hurricane that declared: “We Know Who Is To Blame” beside the names of oil companies, or the campaign in Vermont to create a climate superfund paid for by polluters that would allay the rising costs from floods, storms and heatwaves.

“This is a threat to civilisation as we know it,” he said. “If business as usual continues we won’t have a livable planet for our children and grandchildren. We must collect political, corporate and political will to avoid the worst threat that climate change poses. We can do this.”

The Guardian approached Exxon, BP, Chevron , Total Energies, Coal India, Saudi Aramco and Gazprom for comment.

A spokesperson for Shell said: “Shell is committed to becoming a net-zero emissions energy business by 2050, a target we believe supports the more ambitious goal of the Paris agreement to limit global warming to 1.5C above pre-industrial levels. We continue to make good progress on our climate targets, and by the end of 2023, we had achieved more than 60% of our target to halve Scope 1 and 2 emissions from our operations by 2030, compared with 2016.”

Greenhouse gas emissions
Fossil fuels
Oil and gas companies
Climate crisis

Most viewed

COMMENTS

Essay on Greenhouse Effect for Students
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 ...
Greenhouse gas
greenhouse gas, any gas that has the property of absorbing infrared radiation (net heat energy) emitted from Earth's surface and reradiating it back to Earth's surface, thus contributing to the greenhouse effect. Carbon dioxide, methane, and water vapour are the most important greenhouse gases. (To a lesser extent, surface-level ozone, nitrous oxides, and fluorinated gases also trap ...
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.. 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 ...
Greenhouse gases, facts and information
Effects of greenhouse gases. Greenhouse gases have far-ranging environmental and health effects. They cause climate change by trapping heat, and they also contribute to respiratory disease from ...
Greenhouse Effect
Greenhouse gas emissions increased 70 percent between 1970 and 2004. Emissions of carbon dioxide, the most important greenhouse gas, rose by about 80 percent during that time. The amount of carbon dioxide in the atmosphere today far exceeds the natural range seen over the last 650,000 years.
The Causes of Climate Change
Takeaways. The greenhouse effect is essential to life on Earth, but human-made emissions in the atmosphere are trapping and slowing heat loss to space. Five key greenhouse gases are carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, and water vapor. While the Sun has played a role in past climate changes, the evidence shows the ...
Greenhouse Gases
Greenhouse Gases. Greenhouse gases are gases—like carbon dioxide (CO 2 ), methane, and nitrous oxide—that keep the Earth warmer than it would be without them. The reason they warm the Earth has to do with the way energy enters and leaves our atmosphere. When energy from the sun first reaches us, it does so mainly as light.
Greenhouse effect
greenhouse effect, a warming of Earth's surface and troposphere (the lowest layer of the atmosphere) caused by the presence of water vapour, carbon dioxide, methane, and certain other gases in the air. Of those gases, known as greenhouse gases, water vapour has the largest effect.. The origins of the term greenhouse effect are unclear. French mathematician Joseph Fourier is sometimes given ...
The Science of Climate Change Explained: Facts, Evidence and Proof
Definitive answers to the big questions. For more than a century, scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming. These gases make up ...
5 things you should know about the greenhouse gases warming ...
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.
Global warming
Modern global warming is the result of an increase in magnitude of the so-called greenhouse effect, a warming of Earth's surface and lower atmosphere caused by the presence of water vapour, carbon dioxide, methane, nitrous oxides, and other greenhouse gases. In 2014 the IPCC first reported that concentrations of carbon dioxide, methane, and ...
21.1: The Greenhouse Effect and Climate Change
The greenhouse effect also happens with the entire Earth. Of course, our planet is not surrounded by glass windows. Instead, the Earth is wrapped with an atmosphere that contains greenhouse gases (GHGs).Much like the glass in a greenhouse, GHGs allow incoming visible light energy from the sun to pass, but they block infrared radiation that is radiated from the Earth towards space (figure ...
Greenhouse gases: Causes, sources and environmental effects
The greenhouse effect, in turn, is one of the leading causes of global warming. The most significant greenhouse gases, according to the Environmental Protection Agency (EPA), are: water vapor (H2O ...
Climate Change: Evidence and Causes: Update 2020
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 ...
What Is Climate Change?
Global warming is the long-term heating of Earth's surface observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere. This term is not interchangeable with the term "climate change."
Earth Reacts to Greenhouse Gases More Strongly Than We Thought
Climate change, caused by human greenhouse gas emissions, is in itself a form of planetary geoengineering, he added. ... Hansen has co-authored dozens of papers on climate change in the years ...
Global Warming: Carbon Dioxide and the Greenhouse Effect
- background essay is a great summary of how photosynthesis works, how humans are adding extra carbon into the atmosphere, and how greenhouse gas molecules trap the heat. About the Pedagogy This resource includes a background essay, simple discussion questions, and links to national and state standards.
How Do We Reduce Greenhouse Gases?
To stop climate change, we need to stop the amount of greenhouse gases, like carbon dioxide, from increasing.For the past 150 years, burning fossil fuels and cutting down forests, which naturally pull carbon dioxide out of the air, has caused greenhouse gas levels to increase. There are two main ways to stop the amount of greenhouse gases from increasing: we can stop adding them to the air ...
The race to zero emissions, and why the world depends on it
2010-2019 is the warmest decade on record. On the current path of carbon dioxide emissions, the global temperature is expected to increase by 3 to 5 degrees Celsius by the end of century. To avoid the worst of warming (maximum 1.5°C rise), the world will need to decrease fossil fuel production by roughly 6 per cent per year between 2020 and 2030.
What Is Climate Change?
The main greenhouse gases that are causing climate change include carbon dioxide and methane. These come from using gasoline for driving a car or coal for heating a building, for example. Clearing ...
The Greenhouse Effect: Science and Policy
Global warming from the increase in greenhouse gases has become a major scientific and political issue during the past decade. That infrared radiation is trapped by greenhouse gases and particles in a planetary atmosphere and that the atmospheric CO 2 level has increased by some 25 percent since 1850 because of fossil fuel combustion and land use (largely deforestation) are not controversial ...
What drives greenhouse gas emissions? An international scoping review
Greenhouse gas (GHG) emissions have increased globally 10% in the last decade, but there is a large variation in emissions trajectories by country. ... The papers in our review observed a statistically significant association for 97 independent variables, with population, energy consumption, and GDP per capita being the most common variables ...
Why Greenhouse Gas Emissions Hit an All-Time High Last Year
Carbon dioxide. Last year, humans spewed some 36.6 billion tons of CO2 into the atmosphere, the most ever. That number may well be higher this year. The concentration of carbon dioxide in the ...
Global Greenhouse Gas Overview
Global Emissions and Removals by Gas. At the global scale, the key greenhouse gases emitted by human activities are: Carbon dioxide (CO 2): Fossil fuel use is the primary source of CO 2.CO 2 can also be emitted from the landscape through deforestation, land clearance for agriculture or development, and degradation of soils. Likewise, land management can also remove additional CO 2 from the ...
Globalization and Greenhouse Gas Emissions: Evidence from the United
Issue Date January 2021. The US has been a global leader in regulating local air pollution and a global laggard in regulating greenhouse gases (GHGs). For decades, critics of US policy have expressed fears that stringent US regulations on local air pollution would lead to pollution havens overseas. Prior research, suggests that has not happened.
Greenhouse gases continued to climb in 2023, threatening the climate
The 2023 methane increase over 2022 was 10.9 ppb. In 2023, levels of nitrous oxide, the third-most significant human-caused greenhouse gas, climbed by 1 ppb to 336.7 ppb. "Fossil fuel pollution ...
No sign of greenhouse gases increases slowing in 2023
Levels of the three most important human-caused greenhouse gases - carbon dioxide (CO 2), methane and nitrous oxide - continued their steady climb during 2023, according to NOAA scientists.. While the rise in the three heat-trapping gases recorded in the air samples collected by NOAA's Global Monitoring Laboratory (GML) in 2023 was not quite as high as the record jumps observed in recent ...
NOAA finds greenhouse gases spiked to record in 2023
Levels of greenhouse gases continued to climb at steep rates, reaching a high not seen since well before the history of human civilization, according to NOAA data.. Why it matters: The Earth's atmosphere now contains more planet-warming gases than it has at any other point since at least about 4.3 million years ago. The findings may be a warning sign for the trajectory of modern-day climate ...
A mere 57 mega polluters produce bulk of the world's greenhouse gas
In short: Just 57 companies are responsible for 80 per cent of the world's greenhouse gas emissions, according to a new report released by UK-based think tank InfluenceMap. The report also reveals ...
Just 57 companies linked to 80% of greenhouse gas emissions since 2016
A mere 57 oil, gas, coal and cement producers are directly linked to 80% of the world's global fossil CO2 emissions since the 2016 Paris climate agreement, a study has shown.

Essay on Greenhouse Effect for Students and Children

Causes of Greenhouse Effect

Some Effects of Greenhouse Effect

600 Words Essay on Greenhouse Effect

Greenhouse Gases

Global Warming and the Greenhouse Effect

I. Natural Causes

II. Man-made Causes

Customize your course in 30 seconds

Leave a Reply Cancel reply

Download the App

Carbon dioxide levels are at a record high. Here's what you need to know.

Major greenhouse gases and sources

FREE BONUS ISSUE

You May Also Like

What exactly is lab-grown meat? Here’s what you need to know.

Sea levels are rising at an extraordinary pace. Here's what to know.

Another weapon to fight climate change? Put carbon back where we found it

Effects of greenhouse gases

How to reduce greenhouse gas emissions

Related Topics

How the historic climate bill will dramatically reduce U.S. emissions

Rest in … compost? These ‘green funerals’ offer an eco-friendly afterlife.

‘It’s now or never’: UN climate report’s 4 urgent takeaways

The scientific case against gas stoves

The gas in this exploding mine is odorless, colorless—and could transform the world

History & Culture

Greenhouse Effect

Loading ...

Audio & Video

Illustrators

User Permissions

Interactives

Related Resources

New to Climate Change?

The focus on “carbon”

More Resources for Learning

Radiative Forcing

Carbon Pricing

The Paris Agreement

21.1: The Greenhouse Effect and Climate Change

Earth’s Temperature is a Balancing Act

The Greenhouse Effect Causes the Atmosphere to Retain Heat

What is Global Warming?

What is Climate Change?

The Main Greenhouse Gasses

Other Greenhouse Gasses

Changes in the Sun’s Energy Affect how Much Energy Reaches Earth

Changes in Reflectivity Affect How Much Energy Enters Earth’s System

Scientific Consensus: Global Climate Change is Real

Current Status of Global Climate Change and Future Changes

Past and Present-day GHG Emissions Will Affect Climate Far into the Future

Future Temperature Changes

Future Precipitation and Storm Events

Future Ice, Snowpack, and Permafrost

Future Sea Level Change

Future Ocean Acidification

Mismatched Interactions

Spread of Disease

Climate Change Affects Everyone

Suggested Supplementary Reading

Attributions

Greenhouse gases: Causes, sources and environmental effects

Solar radiation and the "greenhouse effect"

Additional resources

How greenhouse gases cause global warming

Sources of greenhouse gases

Our planet's future

Sign up for the Live Science daily newsletter now

Most Popular

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

A CKNOWLEDGEMENTS

F OR FURTHER READING

Welcome to OpenBook!

Get Email Updates

What Is Climate Change?

What Is Global Warming?

Weather vs. Climate

Find Out More: A Guide to NASA’s Global Climate Change Website

Other NASA Resources