greenhouse gases Overview of Greenhouse Gases carbon dioxide, nitrous oxide and methane greenhouse gases http://www3.epa.gov/climatechange/ghgemissions/gases.html greenhouse gas according United States Environmental Protection Authority website greenhouse gases greenhouse gas methane contributed roughly 10 percent greenhouse gases greenhouse emissions greenhouse gases global warming gases greenhouses gases greenhouse gases greenhouse gases http://www3.epa.gov/climatechange/ghgemissions/gases.html greenhouse gases greenhouse gases greenhouse gases https://www3.epa.gov/climatechange/ghgemissions/gases.html EPA GHG Overview U.S. Environmental Protection Agency website http://www3.epa.gov/climatechange/ghgemissions/gases.html greenhouse gas greenhouse gases carbon emissions represent 81% of the total greenhouse gases