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Greenhouse gases

Graph 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. These gases have an effect similar to the glass roof of a greenhouse which allows the sun's rays to penetrate the atmosphere to heat the earth, but prevent the energy from being radiated back into space.

Also sometimes known as "heat trapping gases," greenhouse gases are natural or manmade gases that trap heat in the atmosphere and contribute to the greenhouse effect. Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and fluorinated gases.

People produce larger amounts of some greenhouse gases than others. Carbon dioxide is the greenhouse gas you hear people talk about the most. That's because we produce more carbon dioxide than any other greenhouse gas, and it's responsible for most of the warming.

Not all greenhouse gases are created equal! Some trap more heat than others. For example, one pound of methane traps about 21 times as much heat as one pound of carbon dioxide. Some greenhouse gases stay in the atmosphere for only a short time, but others can stay in the atmosphere and affect the climate for thousands of years.

The main human sources of greenhouse gas emissions are fossil fuel use, deforestation, intensive livestock farming, use of synthetic fertilizers and industrial processes.

These greenhouse gases don't just stay in one place after they're added to the atmosphere. As air moves around the world, greenhouse gases become globally mixed, which means the concentration of a greenhouse gas like carbon dioxide is roughly the same no matter where you measure it. Even though some countries produce more greenhouse gases than others, emissions from every country contribute to the problem. That's one reason why climate change requires global action.

GHG Emission
International Energy Agency, World Energy Outlook (2015)
International Energy Agency, CO2 Highlights (2015)
U.S. Environmental Protection Agency, International Non CO2 Projections (2015)