Global Warming Potential (GWP) - permalink
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- The index used to translate the level of emissions of various gases into a common measure in order to compare the relative radiative forcing of different gases without directly calculating the changes in atmospheric concentrations. GWPs are calculated as the ratio of the radiative forcing that would result from the emissions of one kilogram of a greenhouse gas to that from emission of one kilogram of carbon dioxide over a period of time (usually 100 years). The chart below shows the original GWPs (assigned in 1990) and the most recent GWPs (assigned in 1996) for the most important greenhouse gases. GASGWP 1990GWP 1996Carbon Dioxide11Methane2221Nitrous Oxide270310HFC-134a1,2001,300HFC-2310,00011,700HFC-152a150140HCF-125NA*2,800PFCs**5,4007,850SF6NA*23,900* Not Applicable. GWP was not yet estimated for this gas.**This figure is an average GWP for the two PFCs, CF4 and C2F6.See radiative forcing, carbon equivalent, carbon dioxide equivalent.
EPA - Cite This Source - This Definition - Global Warming Potential (GWP) is defined as the cumulative radiative forcing effects of a gas over a specified time horizon resulting from the emission of a unit mass of gas relative to a reference gas. The GWP-weighted emissions of direct greenhouse gases in the U.S. Inventory are presented in terms of equivalent emissions of carbon dioxide (CO2), using units of teragrams of carbon dioxide equivalents (Tg CO2 Eq.).
Conversion: Tg = 109 kg = 106 metric tons = 1 million metric tons
The molecular weight of carbon is 12, and the molecular weight of oxygen is 16; therefore, the molecular weight of CO2 is 44 (i.e., 12+[16 x 2]), as compared to 12 for carbon alone. Thus, carbon comprises 12/44ths of carbon dioxide by weight.
See radiative forcing, carbon dioxide equivalent.
EPA - Cite This Source - This Definition - Browse Related Terms: Carbon Dioxide Equivalent, Carbon Equivalent, Metric Ton, Short Ton