Glossary entry

Carbon Dioxide Equivalent (CO2e or CO2eq)


Option 1

Carbon Dioxide Equivalent ( CO2e or CO2eq ) means the standard metric measure to compare the global warming potential of various Greenhouse Gases ( GHGs ) over a specified timescale. [It allows a Carbon Footprint consisting of different GHGs to be expressed as a single number].

Option 2

Carbon Dioxide Equivalent ( CO2e or CO2eq ) means a unit of measurement that is used to standardise the climate effects of various Greenhouse Gases.

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Drafting notes

Global warming potential

The various Greenhouse Gases (GHGs) contribute to the greenhouse effect to different extents and remain in the atmosphere for different periods of time.

To make the effects of different GHGs comparable, the Intergovernmental Panel on Climate Change of the United Nations ( IPCC ) has defined the Global Warming Potential ( GWP ) for each GHG.

This index expresses the warming effect of a certain amount of a GHG over a set period of time (usually 100 years) when compared to carbon dioxide ( CO2 ). For example, methane’s effect on the climate is 28 times more severe than CO2, but it doesn’t stay in the atmosphere as long.


Used in the definition of TCLP glossary terms:

This definition has a very wide application, being a useful metric.

It can be used in any document where you would otherwise refer simply to carbon or GHGs, for example supply chain clauses, national climate laws, project finance documents (e.g. loan, guarantee and recourse agreements, engineering, procurement and construction contracts), policy documents.