Overview of Greenhouse Gases

Gases that trap heat in the atmosphere are called greenhouse gases and these are:

• Carbon dioxide (CO2): Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas, and oil), solid waste, trees and wood products, and also as a result of certain chemical reactions (e.g., manufacture of cement). Carbon dioxide is removed from the atmosphere (or "sequestered") when it is absorbed by plants as part of the biological carbon cycle.
• Methane (CH4): Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.
• Nitrous oxide (N2O): Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.

CO2 emissions are the primary greenhouse gas emissions and they account (in 2015) for about 82.2 % of all U.S. greenhouse gas emissions from human activities. In 2015, CH4 accounted for 10 %, whereas N2O for 5 %.

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