A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated to be 25 times that of carbon dioxide (CO ₂ ). Methane is produced by anaerobic (oxygen-free) decomposition of waste in landfills, animal digestion, decomposition of animal waste, production and distribution of natural gas and oil, coal production and incomplete combustion of fossil fuels. GWP is from the Fourth Assessment Report of the IPCC (AR4). For more information, visit the EPA's page on methane.

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