Global greenhouse gases emitted by human activities are given below.
|Gas||Chemical Formula||% contribution to global greenhouse gas emissions||Sources||Global Warming Potential (GWP100)*||Length of stay in the atmosphere|
|Carbon Dioxide||CO2||76||Burning fossil fuels & wood, deforestation, land clearing for agriculture||1||Some is absorbed quickly (for example, by the ocean surface), but some will remain in the atmosphere for thousands of years|
|Methane||CH4||16||Production and transport of some fossil fuels, agricultural activities, waste management, energy use, biomass burning||21-28||About a decade|
|Nitrous Oxide||N2O||6||Fertiliser use, fossil fuel combustion, industrial activities||265-310||More than a century|
|Fluorinated gases or F-gases||Group of gases that contain fluorine, including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)||2||Industrial processes, refrigeration, a variety of consumer products. Sometimes used as substitutes for ozone-depleting substances such as chlorofluorocarbons (CFCs).||Hundreds to thousands depending on the exact gas||Centuries|
(*) IPCC keeps updating GWP values with each of its scientific assessment reports as its scientific understanding improves. See “What Is Global Warming Potential?” (OneSharedEarth, 2020) for more.
“Global Greenhouse Gas Emissions Data” (US Environmental Protection Agency, 2016)
“Climate Change Indicators: Greenhouse Gases” (US Environmental Protection Agency, 2017)
“Understanding Global Warming Potentials” (US Environmental Protection Agency, 2019)