View source for Global Warming Potential

== Definition ==
'''Global Warming Potential''' (GWP) is a factor describing the radiative forcing impact (degree of harm to the atmosphere) of one unit of a given GHG relative to one unit of CO<sub>2</sub>.<ref>The Greenhouse Gas Protocol, A corporate accounting and reporting standard, Revised Edition 2008</ref>

CO2e is a universal unit of measurement that accounts for the global warming potential (GWP) when measuring and comparing GHG emissions from different gases. The time period generally used for GWP is 100 years. There are also 20-year GWPs that are available. The GWP remains constant for carbon dioxide over different time frames but there is a significant difference in the values of other gases. GWP 20 may be useful to measure impacts of gases that have a shorter lifetime. 

== Usage Example ==
Cities using the [[GPC Protocol]] shall use GWP 100 as a standard but may choose to also separately report, as additional information, estimates obtained using GWP 20 values. <ref>Global Protocol for Community-Scale Greenhouse Gas Inventories, An Accounting and Reporting Standard for Cities, Version 1.1, 2021. WRI, C40, IOCLEI</ref>

Individual GHGs should be converted into CO2e by multiplying by the 100-year GWP coefficients in the latest version of the IPCC Guidelines or the version used by the country’s national inventory body. Where this is not possible (e.g., when the best available emission factors are expressed only in CO2e and not listed separately by gas), an accompanying explanation should be provided. It is important that cities use the same GWP throughout the inventory and explicitly mention if GWP 20 is being used.

== See Also ==
* [[CO2 Equivalent]]

== References ==
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[[Category:GHG Protocol]]