Frequently asked questions

How much does methane contribute to greenhouse gas emissions

Methane (CH4) is the second most prevalent greenhouse gas emitted from human activities. In 2014, CH4 accounted for about 10.6% of all U.S. greenhouse gas emissions from human activities.

Methane is emitted by natural sources such as wetlands, as well as human activities such as leakage from landfill and the raising of livestock. Natural processes in soil and chemical reactions in the atmosphere help remove CH4 from the atmosphere.

Methane's lifetime in the atmosphere is much shorter than carbon dioxide (CO2), but CH4 is more efficient at trapping radiation than CO2. On a weight basis the comparative impact of CH4 on climate change is more than 25 times greater than CO2 over a 100-year period.