CO2 equivalent

This includes carbon dioxide (CO₂) as well as other greenhouse gases. These are nitrous oxide (N₂O), methane (CH₄) and fluorinated gases (F-gases). In order to calculate the combined impact of the various greenhouse gases, emission levels are converted to CO₂ equivalent. This conversion is based on the ‘global warming potential’ (GWP) of each gas, i.e. the degree to which it contributes to the greenhouse effect.

One kg of CO₂ equivalent has the same effect as one kg of CO₂. The emission of 1 kg of nitrous oxide is the equivalent of 298 kg of CO₂, for example, and the emission of 1 kg of methane is the equivalent of 25 kg of CO₂. The GWPs of fluorinated gases vary greatly and can be very high. For example, 1 kg of sulphur hexafluoride is the equivalent of 22.8 thousand kg of CO₂.

Greenhouse gas emissions are generally expressed in megatonnes of CO₂ equivalent (1 megatonne = 1 million tonnes = 1 billion kilograms).

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