The Global Warming Potential (GWP) of a gas is a measure of the degree, relative to carbon dioxide, to which the presence of that gas in the atmosphere will contribute to a long-term increase in global temperature. The calculation of the GWP for a given gas takes into account the efficiency of the gas in absorbing solar radiation (primarily determined by the infrared spectrum of the compound) and the time the compound will remain in the atmosphere before it is removed by natural processes. Thus, if a pulse of 1 kg of the gas is emitted to the atmosphere at the same time as a pulse of 1 kg of CO2, the GWP compares the warming effect of the gas relative to CO2 over various time horizons.
This table, which is taken from the 2014 and 2007 reports of the Intergovernmental Panel of Climate Change (IPCC) (Refs. 1 and 2), gives the lifetime in years and the radiative efficiency for the major compounds identified in the Kyoto Protocol as contributing to global climate change. The data columns are defined as follows.
Column heading | Definition |
Name | Compound chemical name |
Synonym/Code | Common synynom or industrial designation |
Mol. form. | Molecular formula |
Lifetime | Lifetime of the compound, in years |
Radiative efficiency | A measure of the radiative forcing that influences the energy balance in the Earth–atmosphere system; in units of watts per square meter for a concentration of one part per billion (W m-2 ppb-1) (see Refs. 1 and 2) |
GWP 100-yr est. (2014) | Global Warming Potential for a 100-year horizon; as estimated by the IPCC in 2014 (Ref. 2) |
GWP 100-yr est. (2007) | Global Warming Potential for a 100-year horizon; as estimated by the IPCC in 2007 (Ref. 1) |
GWP 100-yr est. (1995) | Global Warming Potential for a 100-year horizon; as estimated by the IPCC in 1995 |
GWP 20-yr est. (2007) | Global Warming Potential for a 20-year horizon; as estimated by the IPCC in 2007 (Ref. 1) |
GWP 500-yr est. (2007) | Global Warming Potential for a 500-year horizon; as estimated by the IPCC in 2007 (Ref. 1) |
The calculation of a GWP involves a number of assumptions, and other measures have been proposed (see Refs 1 and 2).
The list of compounds includes those identified in the Montreal Protocol as contributing to ozone depletion, since these compounds also contribute to global warming. It also includes compounds used or proposed as replacements for the ozone-depleting compounds that still have global warming potential.
Name | Synonym/Code | Mol. form. | Lifetime (years) | Radiative efficiency/ W m-2 ppb-1 | GWP 100-yr est. (2014) | GWP 100-yr est. (2007) | GWP 100-yr est. (1995) | GWP 20-yr est. (2007) | GWP 500-yr est. (2007) |
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Natural atmospheric constituents | |||||||||
Carbon dioxide | CO2 | 0.000014 | 1 | 1 | 1 | 1 | 1 | ||
Methane | CH4 | 12 | 0.00037 | 28 | 25 | 21 | 72 | 7.6 | |
Nitrous oxide | N2O | 114 | 0.00303 | 298 | 310 | 289 | 153 | ||
Substances controlled by the Montreal Protocol | |||||||||
Trichlorofluoromethane | CFC-11 | CCl3F | 45 | 0.25 | 4600 | 4750 | 3800 | 6730 | 1620 |
Dichlorodifluoromethane | CFC-12 | CF2Cl2 | 100 | 0.32 | 10200 | 10900 | 8100 | 11000 | 5200 |
Chlorotrifluoromethane | CFC-13 | CF3Cl | 640 | 0.25 | 13900 | 14400 | 10800 | 16400 | |
1,1,2-Trichloro-1,2,2-trifluoroethane | CFC-113 | CFCl2CF2Cl | 85 | 0.3 | 5820 | 6130 | 4800 | 6540 | 2700 |
1,2-Dichloro-1,1,2,2-tetrafluoroethane | CFC-114 | C2Cl2F4 | 300 | 0.31 | 8590 | 10000 | 8040 | 8730 | |
Chloropentafluoroethane | CFC-115 | CF3CF2Cl | 1700 | 0.18 | 7670 | 7370 | 5310 | 9990 | |
Bromotrifluoromethane | Halon-1301 | CF3Br | 65 | 0.32 | 6290 | 7140 | 5400 | 8480 | 2760 |
Bromochlorodifluoromethane | Halon-1211 | CF2BrCl | 16 | 0.3 | 1750 | 1890 | 4750 | 575 | |
1,2-Dibromotetrafluoroethane | Halon-2402 | CF2BrCF2Br | 20 | 0.33 | 1470 | 1640 | 3680 | 503 | |
Tetrachloromethane | Carbon tetrachloride | CCl4 | 26 | 0.13 | 1730 | 1400 | 1400 | 2700 | 435 |
Bromomethane | Methyl bromide | CH3Br | 0.7 | 0.01 | 2 | 5 | 17 | 1 | |
1,1,1-Trichloroethane | Methyl chloroform | CH3CCl3 | 5 | 0.06 | 160 | 146 | 506 | 45 | |
Chlorodifluoromethane | HCFC-22 | CHClF2 | 12 | 0.2 | 1760 | 1810 | 1500 | 5160 | 549 |
2,2-Dichloro-1,1,1-trifluoroethane | HCFC-123 | CHCl2CF3 | 1.3 | 0.14 | 79 | 77 | 90 | 273 | 24 |
1-Chloro-1,2,2,2-tetrafluoroethane | HCFC-124 | CHClFCF3 | 5.8 | 0.22 | 527 | 609 | 470 | 2070 | 185 |
1,1-Dichloro-1-fluoroethane | HCFC-141b | CH3CCl2F | 9.3 | 0.14 | 782 | 725 | 2250 | 220 |