Editing IPCC:AR6/WGIII/Chapter-1 (section)

=== FAQ 1.2 | Which greenhouse gases (GHGs) are relevant to which sectors? ===

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Anthropogenic GHGs such as carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O), and fluorinated gases (e.g., hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride) are released from various sources. CO 2 makes the largest contribution to global GHG emissions, but some have extremely long atmospheric lifetimes extending to tens of thousands of years, such as F-gases (Chapter 2).

Different combinations of gases are emitted from different activities. The largest source of CO 2 is combustion of fossil fuels in energy conversion systems like boilers in electric power plants, engines in aircraft and automobiles, and in cooking and heating within homes and businesses (approximately 64% of emissions, Figure SPM.2). Fossil fuels are also a major source of methane (CH 4 ), the second biggest contributor to global warming. While most GHGs come from fossil fuel combustion, about one quarter comes from land-related activities like agriculture (mainly CH 4 and N 2 O) and deforestation (mainly CO 2 ), with additional emissions from industrial processes (mainly CO 2 , N 2 O and F-gases), and municipal waste and wastewater (mainly CH 4 ) (Chapter 2). In addition to these emissions, black carbon – an aerosol that is, for example, emitted during incomplete combustion of fossil fuels – contributes to warming of the Earth’s atmosphere, whilst some other short-lived pollutants temporarily cool the surface (IPCC AR6 WGI [[IPCC:Wg3:Chapter:Chapter-6#6.5.4|Section 6.5.4]] .3).

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