Global Warming Potential (GWP)

Global warming potential expresses the warming caused by a unit mass of a greenhouse gas relative to carbon dioxide over a chosen horizon, conventionally 100 years. Methane has a GWP-100 of about 28 to 30 and nitrous oxide about 265 to 273 in the IPCC AR5 values, which is why methane slip from gas engines and N2O from combustion matter despite their small mass. GWP is the conversion that turns a basket of gases into a single CO2-equivalent figure.