CO2e Equivalent carbon dioxide: CO2e, is a standard unit for comparing different greenhouse gases. Each greenhouse gas is described in terms of the concentration of CO2 that would have the same impact on the flow of energy (i.e. the same radiative forcing) in the atmosphere.

CO2eq – Carbon dioxide equivalency. The amount of emitted carbon dioxide that would have the same effect as the emissions of another greenhouse gas, over a given period, usually 100 years.

tC02eq Metric tonnes of equivalent carbon dioxide. 1 metric tonne = 1000kg.

GtCO2eq Gigatonnes of equivalent carbon dioxide: x109 metric tonnes of CO2 equivalent, or x1012 kg

ppm CO2eq parts per million by volume of equivalent carbon dioxide:

PgC Petagrams of Carbon (PgC; x1015gC)

Tg(CH4) Teragrams of methane (x1012g)

Gt Gigatonnes (x109 tonnes or x1012kg)

Mt CO2 Megatonnes of carbon dioxide (x106 tonnes, or x109kg)

ppm parts per million by volume – a unit which refers to the relative concentration of a substance.

pCO2 surface ocean partial pressure of CO2, where the partial pressure is a measure of the amount of a gas in a given volume and at a given temperature.

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