Global warming potential: Difference between revisions
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Add timespan. Rm the odd gas (these are only examples; its link was broken) |
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GWP is based on a number of factors, including the radiative efficiency (heat-absorbing ability) of each gas relative to that of carbon dioxide, as well as the decay rate of each gas (the amount removed from the atmosphere over a given number of years) relative to that of carbon dioxide [http://www.eia.doe.gov/oiaf/1605/gwp.html]. The [[Intergovernmental Panel on Climate Change]] (IPCC) provides the generally accepted values for GWP, which changed slightly between 1996 and 2001 (eg methane was assessed a value of 21 in 1996). An exact definition of how GWP is calculated is to be found in the IPCC's [http://www.grida.no/climate/ipcc_tar/wg1/247.htm 2001 Third Assessment Report]. |
GWP is based on a number of factors, including the radiative efficiency (heat-absorbing ability) of each gas relative to that of carbon dioxide, as well as the decay rate of each gas (the amount removed from the atmosphere over a given number of years) relative to that of carbon dioxide [http://www.eia.doe.gov/oiaf/1605/gwp.html]. The [[Intergovernmental Panel on Climate Change]] (IPCC) provides the generally accepted values for GWP, which changed slightly between 1996 and 2001 (eg methane was assessed a value of 21 in 1996). An exact definition of how GWP is calculated is to be found in the IPCC's [http://www.grida.no/climate/ipcc_tar/wg1/247.htm 2001 Third Assessment Report]. |
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Note that a substances GWP depends also on the timespan over which the potential is calculated. Thus methane has a potential of 23 over 100 years but 62 over 20 years; conversely SF6 has a GWP of 22,000 over 100 years but 15,100 over 20 years. |
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'''Examples:''' |
'''Examples:''' |
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100 year horizons: |
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*[[carbon dioxide]] has a GWP of exactly 1 (since it is the baseline unit to which all other greenhouse gases are compared.) |
*[[carbon dioxide]] has a GWP of exactly 1 (since it is the baseline unit to which all other greenhouse gases are compared.) |
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*[[methane]] has a GWP of 23. |
*[[methane]] has a GWP of 23. |
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*[[nitrogen dioxide]] has a GWP of 296 |
*[[nitrogen dioxide]] has a GWP of 296 |
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*the [[hydrofluorocarbon]] [[HFC-23]] has a GWP of 12,000 |
*the [[hydrofluorocarbon]] [[HFC-23]] has a GWP of 12,000 |
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* trifluoromethyl sulfur pentafluoride has a GWP of 18,000 recently dubbed a '''super greenhouse gas'''<sup>[1]</sup>. The source is [[anthropogenic]] but the research shows the source is '''not''' sulfur hexafluoride. |
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*[[sulfur hexafluoride]] (SF<sub>6</sub>) has the highest charted GWP of 22,200, used as high voltage insulator. |
*[[sulfur hexafluoride]] (SF<sub>6</sub>) has the highest charted GWP of 22,200, used as high voltage insulator. |
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*[http://www.epa.gov/nonco2/econ-inv/table.html List of Global Warming Potentials and Atmospheric Lifetimes] from the U.S. [[EPA]] |
*[http://www.epa.gov/nonco2/econ-inv/table.html List of Global Warming Potentials and Atmospheric Lifetimes] from the U.S. [[EPA]] |
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*[http://www.grida.no/climate/ipcc_tar/wg1/247.htm IPCC 2001 Third Assessment Report page on Global Warming Potentials] |
*[http://www.grida.no/climate/ipcc_tar/wg1/247.htm IPCC 2001 Third Assessment Report page on Global Warming Potentials] |
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* <sup>[1]</sup> Federico Pepi, Andreina Ricci, Marco Di Stefano and Marzio Rosi. 2005. Gas phase protonation of trifluoromethyl sulfur pentafluoride. ''Phys. Chem. Chem. Phys.'' 7 (6): 1181-1186 [http://www.rsc.org/CFmuscat/intermediate_abstract.cfm?FURL=/ej/CP/2005/b416945j.PDF] |
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[[Category:Climate change]] |
[[Category:Climate change]] |
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Revision as of 17:32, 18 September 2005
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Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. It is a relative scale which compares the gas in question to that of the same mass of carbon dioxide whose GWP is one.
GWP is based on a number of factors, including the radiative efficiency (heat-absorbing ability) of each gas relative to that of carbon dioxide, as well as the decay rate of each gas (the amount removed from the atmosphere over a given number of years) relative to that of carbon dioxide [1]. The Intergovernmental Panel on Climate Change (IPCC) provides the generally accepted values for GWP, which changed slightly between 1996 and 2001 (eg methane was assessed a value of 21 in 1996). An exact definition of how GWP is calculated is to be found in the IPCC's 2001 Third Assessment Report.
Note that a substances GWP depends also on the timespan over which the potential is calculated. Thus methane has a potential of 23 over 100 years but 62 over 20 years; conversely SF6 has a GWP of 22,000 over 100 years but 15,100 over 20 years.
Examples:
100 year horizons:
- carbon dioxide has a GWP of exactly 1 (since it is the baseline unit to which all other greenhouse gases are compared.)
- methane has a GWP of 23.
- nitrogen dioxide has a GWP of 296
- the hydrofluorocarbon HFC-23 has a GWP of 12,000
- sulfur hexafluoride (SF6) has the highest charted GWP of 22,200, used as high voltage insulator.