A metric measure used to compare emissions from different greenhouse gases based on their global warming potential (GWP). Carbon dioxide equivalents are commonly expressed as "million metric tons of carbon dioxide equivalents (MMTCO ₂ Eq). The carbon dioxide equivalent for a gas is derived by multiplying the tonnes of gas by the relevant GWP.

MMTCO ₂ Eq = (million metric tons of gas) * (GWP of gas)

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