Global Warming Potential (GWP).
Some greenhouse gases are more powerful than others in
terms of radiative forcing.
Global Warming Potential (GWP) is 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). Gases involved
in complex atmospheric chemical processes have not been assigned GWPs due
to complications that arise. Greenhouse gases are expressed in terms of
Carbon Dioxide Equivalent. The International Panel on Climate Change (IPCC)
has presented these GWPs and regularly updates them in new assessments.
The chart below shows the original GWPs (assigned in 1990) and the most
recent GWPs (assigned in 1996) for the most important greenhouse gases.
| GAS |
GWP 1990 |
GWP 1996 |
| Carbon Dioxide |
1 |
1 |
| Methane |
22 |
21 |
| Nitrous Oxide |
270 |
310 |
| HFC-134a |
1,200 |
1,300 |
| HFC-23 |
10,000 |
11,700 |
| HFC-152a |
150 |
140 |
| HCF-125 |
NA* |
2,800 |
| PFCs** |
5,400 |
7,850 |
| SF6 |
NA* |
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.