Carbon Dioxide Equivalent

The amount of CO2 emissions that would cause the same integrated radiative forcing or temperature change, over a given time horizon, as an emitted amount of a GHG or a mixture of GHGs. There are a number of ways to compute such equivalent emissions and choose appropriate time horizons. Most typically, the CO2e emission is obtained by multiplying the emission of a GHG by its global warming potential (GWP) for a 100-year time horizon. For a mix of GHGs, it is obtained by summing the CO2e emissions of each gas. CO2e emission is a common scale for comparing emissions of different GHGs but does not imply equivalence of the corresponding climate change responses. There is generally no connection between CO2e emissions and resulting CO2e concentrations. In other words, CO2e is a metric used to place emissions of various radiative forcing agents on a common footing by accounting for their effect on climate. It describes, for a given mixture and amount of GHGs, the amount of CO2 that would have the same global warming ability when measured over a 100 year time horizon. Conversion factors vary based on the underlying assumptions and as the science advances.