Mitigation is the human intervention to reduce the sources or enhance the sinks of greenhouse gases (GHGs). The AR5 WGIII report also assesses human interventions to reduce the sources of other substances which may contribute directly or indirectly to limiting climate change, including, for example, the reduction of particulate matter (PM) emissions that can directly alter the radiation balance (e.g., black carbon) or measures that control emissions of carbon monoxide, nitrogen oxides (NOx), Volatile Organic Compounds (VOCs) and other pollutants that can alter the concentration of tropospheric ozone (O3) which has an indirect effect on the climate.
Source: IPCC