write a essay on green house gases

Essay on Greenhouse Effect for Students and Children

500 words essay on greenhouse effect.

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

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

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

Causes of Greenhouse Effect

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

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

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

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Some Effects of Greenhouse Effect

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

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

600 Words Essay on Greenhouse Effect

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

Greenhouse Gases

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

Global Warming and the Greenhouse Effect

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

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

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

There are broadly two causes of the greenhouse effect:

I. Natural Causes

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

II. Man-made Causes

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

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

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21.1: The Greenhouse Effect and Climate Change

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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 )

By absorbing much of the added heat trapped by atmospheric greenhouse gases, the oceans are delaying some of the impacts of climate change. Photo: WMO/Olga Khoroshunova

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

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

1. What is the greenhouse effect?

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

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

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

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

On bone-dry land, severely affected by drought, two women search for their daily water supply.

2. Why does the warming matter?

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

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

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

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

Carbon dioxide levels continue at record levels, despite the economic slowdown caused by the COVID-19 pandemic.

3. What are the major greenhouse gases?

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

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

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

4. How is human activity producing these greenhouse gases?

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

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

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

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

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

Wind farms generate electricity and reduce reliance on coal-powered energy.

5. What can we do to reduce GHG emissions?

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

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

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

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

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

UNEP’s role in reducing GHGs

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

Understanding Global Change

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

Greenhouse effect

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

Global Change Infographic

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

Adapted from the Environmental Protection Agency greenhouse effect file

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

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

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

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

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

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

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

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

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

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

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

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 .

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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.

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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.

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What is the greenhouse effect?

Scientists have determined that carbon dioxide plays a crucial role in maintaining the stability of Earth's atmosphere. If carbon dioxide were removed, the terrestrial greenhouse effect would collapse, and Earth's surface temperature would drop significantly, by approximately 33°C (59°F).

Greenhouse gases are part of Earth's atmosphere. This is why Earth is often called the 'Goldilocks' planet – its conditions are just right, not too hot or too cold, allowing life to thrive. Part of what makes Earth so amenable is its natural greenhouse effect, which maintains an average temperature of 15 ° C (59 ° F) . However, in the last century, human activities, primarily from burning fossil fuels that have led to the release of carbon dioxide and other greenhouse gases into the atmosphere, have disrupted Earth's energy balance. This has led to an increase in carbon dioxide in the atmosphere and ocean. The level of carbon dioxide in Earth’s atmosphere has been rising consistently for decades and traps extra heat near Earth's surface, causing temperatures to rise.

The Greenhouse Effect (UCAR)
NASA's Climate Kids: Meet the Greenhouse Gases! (downloadable and printable cards)
NASA's Climate Kids: What Is the Greenhouse Effect?

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)

Biology Article
Greenhouse Effect Gases

Greenhouse Effect

Table of Contents

What is the Greenhouse Effect?

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

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

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

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

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

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

Burning of Fossil Fuels

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

Deforestation

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

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

Industrial Waste and Landfills

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

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

The main effects of increased greenhouse gases are:

Global Warming

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

Depletion of Ozone Layer

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

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

Smog and Air Pollution

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

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

Acidification of Water Bodies

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

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

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

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

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

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

Frequently Asked Questions

What is global warming.

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

List gases which are responsible for the greenhouse effect.

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

What is the greenhouse effect?

What are the major causes of the greenhouse effect.

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

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

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

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

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An indoor swimming pool, drained of water, beneath a vaulted glass ceiling, with Olympic rings on the far wall.

In Paris, the Olympics Clean Up Their Act

Organizers of the Games promise to slash greenhouse gas emissions by re-using historic buildings, adding bike lanes, even putting solar panels on the Seine. Will it work?

A pool from the 1924 Paris Olympics is getting a makeover for the 2024 games. Credit... Yulia Grigoryants for The New York Times

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By Somini Sengupta and Catherine Porter

Somini Sengupta and Catherine Porter reported across Paris and the northern suburbs in Seine Saint-Denis.

Published March 16, 2024 Updated March 17, 2024

How do you produce a global sporting event, with millions of people swooping down on one city, in the age of global warming?

That is the test for the Paris Olympics this summer.

The organizers say they’re putting the games on a climate diet. These Olympics, they say, will generate no more than half the greenhouse gas emissions of recent Olympics. That means tightening the belt on everything that produces planet-warming emissions: electricity, food, buildings, and transportation, including the jet fuel that athletes and fans burn traveling the world to get there.

An event that attracts 10,500 athletes and an estimated 15 million spectators is, by definition, going to have an environmental toll. And that has led those who love the games but hate the pollution to suggest that the Olympics should be scattered around the world, in existing facilities, to eliminate the need for so much new construction and air travel. That’s why Paris is being watched so closely.

It is making more space for bikes and less for cars. It’s doing away with huge, diesel-powered generators, a fixture of big sporting events. It’s planning guest menus that are less polluting to grow and cook than typical French fare: more plants, less steak au poivre. Solar panels will float, temporarily, on the Seine.

But the organizers’ most significant act may be what they are not doing: They aren’t building. At least, not as much.

Two construction workers in fluorescent orange work vests bend over a stretch of pavement next to the shovel of an excavating machine.

Instead of building new showpieces for the games (which generates lots of greenhouse gas emissions from the manufacturing of concrete and steel), the Paris Olympics are repurposing many of the city’s existing attractions, including the Grand Palais, the plaza known as the Concorde and even a swimming pool built for the 1924 Paris Olympics.

It’s not without controversy.

One notable emissions-reduction effort, a decision to forego conventional air-conditioning at the athletes’ village, has raised concerns. Instead, the buildings will rely on a cooling system that uses water pulled from underground. Several Olympic teams, are considering bringing their own air-conditioners.

Still the hope is that experiments like these will offer a template for other Olympics in the future, and other cities worldwide. The few new buildings that are being built, including the athletes’ housing, as well as a swimming complex and an arena, are using less cement and more wood. They have solar panels and greenery on their roofs.

The new buildings are also meant to have a life far beyond the Olympics. They’re designed to be used by local residents for decades to come and, the leaders of the Paris 2024 organizing committee say, revitalize the city’s suburbs. “We set for ourselves ambitions that have never been set for any event before, let alone have this scale,” said Georgina Grenon, who is in charge of the games’ environmental efforts.

Critics counter that, while much of what Paris is doing is commendable, particularly the limits on new construction, to truly address the climate crisis requires more than paring back emissions here and there. “We need to fundamentally rethink these huge mega events,” said Cesar Dugast, co-founder of a climate analysis group called Eclaircies. “Instead of concentrating all the events in a single city, it could be envisaged to distribute them around the world.”

‘It’s a big test’

There’s a more immediate risk facing the Olympics: climate change itself. Rising global temperatures are making Paris summers dangerously hot. That has heightened concerns about how to protect athletes and fans in late July and August.

City officials say they have planted thousands of trees in recent years to temper summer heat. They are erecting misting towers to spray the air. The search is on for wide umbrellas under which fans can wait. “We have solutions. We are preparing,” said Dan Lert, the deputy mayor in charge of preparing the city for heat. “It’s a big test.”

One major thing that sets the Paris games apart from previous Olympics is that it has imposed a limit on the total emissions it will produce. The target: Generate no more than half the greenhouse gas emissions of the 2012 Olympics, which were held in London.

London was chosen as a benchmark because the organizers there also sought to reduce emissions, and they measured them. Estimates like these are based on standard measures of, for instance, how much carbon dioxide is produced by the amount of cement used in new buildings.

The Paris organizers say they will offset those emissions by purchasing “carbon credits” to help fund emissions-reducing projects worldwide. The games organizers have not said what projects the games will fund and at what price. In any case, the market for carbon credits can be murky, with some projects not delivering on their promise.

Refashioning a historic city

What Paris is doing shows what can be done to remake an old city for a new global climate. It also shows what the limits are.

The Place de la Concorde, an 18th century plaza where guillotines were once erected during the French Revolution, this summer will be home to Olympic events like skateboarding.

The plaza is also now home to an unassuming metal box designed to spur an electricity revolution. It contains a high-powered electrical outlet connected to the national grid, enabling every big event on the plaza to throw off the shackles of diesel.

Diesel generators are the dirty secret of sports events. Typically they are trucked in to provide a stable source of power.

The Paris games have also cut a special deal with the electric utility stipulating that there be enough wind and solar energy in the grid to produce all the energy that the games consume.

When it comes to emissions, transportation is another headache. Paris has already been limiting space for cars and making space for bikes, and it’s using the games to accelerate that shift.

But the Olympics, with its huge crowds, threatens trouble for how Parisians get around their city, with many making plans to flee on vacation.

Pierre Rabadan, a former pro rugby player who is now Paris’ deputy mayor for sports, lifted his shoulders against a wind and walked briskly out of the tram stop in front of the city’s new basketball arena, at the top of Rue de la Chapelle. He pointed to an almost finished bike lane along the road, carved out of what had been a wide boulevard devoted to automobiles.

Since the election of Anne Hidalgo as mayor in 2014, Paris has added some 600 kilometers of bike lanes. Around 10 percent have been dubbed Olympistes, a play on “piste,” the French word for track.

“The problem is we built the city around cars,” Mr. Rabadan said.

Another problem is that the city’s metro system is bursting at the seams. Trains are already crowded, and workers are rushing to complete new extensions of two lines in time to serve the games.

To make room for Olympics visitors, the city has urged people to stay off the trains or work from home.

Tarzan and the old pool

Key to the organizers’ climate strategy is to build as little as possible, which is why it is tapping into a leftover from the 1924 Paris Olympics: the Georges Vallerey swimming pool.

It’s getting a new air filtration system, as well as a new roof that lets in light but keeps out heat and cold. Old wood roof beams have been repurposed as countertops. The wooden bleachers, installed at least 40 years ago, remain. Sturdy stucco walls reveal the pool’s age.

“We need not trash everything or destroy everything and put it in the bin,” said Mr. Rabadan.

The pool holds history. It is where Johnny Weissmuller, an American swimmer, won a gold medal in 1924. He went on to play Tarzan in a string of Hollywood movies, Mr. Rabadan is keen to point out.

Roughly 95 percent of the venues to be used in the 2024 games are old buildings or temporary structures. For example, several temporary pools will be built for the games, then taken apart and re-installed in communities that have a dearth of public pools.

‘A laboratory’

The Olympics, Ms. Grenon said, offer “a laboratory,” particularly when it comes to the buildings designed from scratch.

A new aquatic center, on the edge of a highway in the northern suburb of Saint-Denis, is a showpiece of Douglas fir and pine. Its 5,000 square meter roof curves like a wave: The architects designed it that way to shrink the size of the building, reducing the energy needed to heat the space.

The pool is 5 meters deep only where necessary to have greater depth for diving, and shallower where it’s not. That too saves water and energy it takes to heat the water. Some of that heat will come from a nearby data center. The venue’s 5,000 seats are made from recycled plastic.

The goal, said Cécilia Gross, one of the architects, was “to do better with less.”

Rising nearby is the biggest new Olympics project: the 128-acre Athletes Village complex that is to morph into a mixed neighborhood for 6,000 residents afterward. Its builders say its emissions are at least 30 percent less than a conventional project of its size.

Timber has a starring role here, too. The village is a cluster of mostly wood-frame buildings.

While timber has its own environmental costs depending on how it’s grown, it is considered far more sustainable than concrete.

In the village, a small patch of sidewalk is paved with oyster shells that can be watered from an underground reservoir and cool the sidewalk on hot days. One experimental building is to recycle all its water. To cool the grounds, 9,000 trees have been planted, including local varieties like oaks and elms that can survive in a hotter future.

Then there’s the unconventional air conditioning.

A network of pipes, using water cooled by first being sent underground, will cool the interiors of the buildings in a technology known as a geo-exchange system. In New York City, St. Patrick’s Cathedral uses something similar, but using air instead of water. A smattering of U.S. universities are also switching to geoexchange.

Along with shade trees, insulation and a breeze from the river, the builders say indoor temperatures can be kept cool enough for the Paris summers of the future. However, the games organizers say, Olympic teams are still free to bring their own air conditioners.

The United States, Canada and Norway said they would. Australia and Ireland have too, according to press reports. The mayor, Ms. Hidalgo, in an interview with Reuters , urged teams to “trust the science.”

Léontine Gallois contributed reporting from Paris.

Because of an editing error, an earlier version of a picture caption with this article stated incorrectly the location of a new electric box that replaced diesel generators. It was on the Place de la Concorde, not near the Grand Palais.

How we handle corrections

Somini Sengupta is the international climate reporter on the Times climate team. More about Somini Sengupta

Catherine Porter is an international reporter for The Times, covering France. She is based in Paris. More about Catherine Porter

The Greenhouse Effect and our Planet

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

Biology, Ecology, Earth Science, Geography, Human Geography

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Greenhouse gases include gases such as carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), ozone (O 3 ), and fluorinated gases. These greenhouse gases allow the sun's light to shine onto Earth's surface. Then the gases, such as ozone, trap the heat that reflects back from the surface inside Earth's atmosphere . The gases act like the glass walls of a greenhouse. In other words, they are warming.

The greenhouse effect happens when these gases gather in Earth's atmosphere. According to scientists, without the greenhouse effect, the average temperature of Earth would drop from 57 degrees Fahrenheit (14 degrees Celsius) to as low as negative 0.4 degrees F (minus 18 degrees C).

Do We Blame the Industrial Revolution ? Some greenhouse gases come from natural sources. For example, evaporation adds water vapor to the atmosphere. Animals and plants release carbon dioxide when they breathe. Methane is released naturally from decomposition, when soils and living things break down. Volcanoes —both on land and under the ocean —release greenhouse gases.

The Industrial Revolution happened in the late 1700s and early 1800s, when factories began producing more. Since then, people have been releasing larger quantities of greenhouse gases into the atmosphere. Greenhouse gas emissions increased 70 percent between 1970 and 2004. Emissions of carbon dioxide (CO 2 ), rose about 80 percent during that time.

The amount of CO 2 in the atmosphere far exceeds Earth's natural amount seen over the last 650,000 years.

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

Human Activity + Greenhouse Gases = A Warming Earth People add methane to the atmosphere through livestock farming, landfills and fossil fuel production such as coal mining and natural gas processing. Nitrous oxide comes from agriculture and fossil fuel burning.

Fluorinated gases include chlorofluoro carbons (CFCs), hydro chlorofluoro carbons (HCFCs), and hydrofluorocarbons (HFCs). They are produced during the manufacturing of refrigeration and cooling products. Some come through aerosol cans , such as some hairsprays or spray paint.

As greenhouse gases increase, so does the temperature of Earth. The rise in Earth's average temperature contributed to by human activity is known as global warming .

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

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

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

The Intergovernmental Panel on Climate Change says that the global sea level rose about 1.8 millimeters (0.07 inch) per year from 1961 to 1993. It rose about 3.1 millimeters (1/8 inch) per year since 1993.

This seems like only a tiny bit, but rising sea levels can cause flooding in cities along the coasts . This could force millions of people in low-lying areas out of their homes, such as in Bangladesh, the U.S. state of Florida, and the Netherlands.

Millions more people in countries such as Peru and India depend on water from melted glaciers . They use it for drinking, watering crops and hydroelectric power . Rapid loss of these glaciers would greatly hurt those countries.

Predictable Rain is Important to Many Greenhouse gas emissions also affect changes in precipitation , such as rain and snow .

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

As climates change, so do the habitats for living things. Animals that are adapted to a certain climates might become threatened. Many humans depend on predictable rain patterns to grow specific crops . If the climate of an area changes, the people who live there may no longer be able to grow the crops they depend on for survival.

Scientists aren't the only Ones Who Can Help

Drive less. Use public transportation , carpool, walk, or ride a bike.
Fly less. Airplanes produce huge amounts of greenhouse gas emissions.
Reduce, reuse, and recycle .
Plant a tree. Trees absorb carbon dioxide, keeping it out of the atmosphere.
Use less electricity .
Eat less meat. Cows are one of the biggest methane producers.
Support alternative energy sources that don’t burn fossil fuels.

Artificial Gas

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

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

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

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

Chapter: conclusion, c onclusion.

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

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

A CKNOWLEDGEMENTS

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

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

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

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

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

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

F OR FURTHER READING

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

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

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

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

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

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

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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

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

1. What is the greenhouse effect?

2. Why does the warming matter?

3. What are the major greenhouse gases?

5. What can we do to reduce GHG emissions?

UNEP’s role in reducing GHGs

Understanding Global Change

Greenhouse effect

On this page

Global Change Infographic

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

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Most Popular

New to Climate Change?

The focus on “carbon”

More Resources for Learning

Radiative Forcing

Carbon Pricing

The Paris Agreement

What is the greenhouse effect?

How Do We Reduce Greenhouse Gases?

Use less electricity.

Generate electricity without emissions.

Shrink the footprint of food.

Travel without making greenhouse gases.

Reduce household waste.

Reduce emissions from industry.

Take carbon dioxide out of the air.

Greenhouse Effect

What is the Greenhouse Effect?

Burning of Fossil Fuels

Deforestation

Industrial Waste and Landfills

Global Warming

Depletion of Ozone Layer

Smog and Air Pollution

Acidification of Water Bodies

Frequently Asked Questions

List gases which are responsible for the greenhouse effect.

What is the greenhouse effect?

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

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