Carbon dioxide equivalent (CO2eq)

Describes the impact of a given GHG (CO2, CO, CH4, N2O, etc.) by converting its mass to the equivalent mass of CO2 that would have the same global warming effect. The mass of a GHG is converted to the mass of CO2eq based on the GHG molecule’s potential to affect global warming, or its global warming potential (GWP). The GWP takes into account both the radiative forcing effect of the GHG and the gas’s lifetime in the atmosphere, and is dependent on the time horizon, which is most commonly 20 years (GWP20) or 100 years (GWP100). These values are different because the GWP is time-integrated and the GWP of CO2 is always 1, regardless of the time horizon. (For more information, see CDR Primer, Chapter 4, Supplement 4.1.)

source: J Wilcox, B Kolosz, & J Freeman (2021) CDR Primer; Concepts