A | B | C | D | E | F | G | H | CH | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
Global Warming Potential (GWP) is an index to measure how much infrared thermal radiation a greenhouse gas would absorb over a given time frame after it has been added to the atmosphere (or emitted to the atmosphere). The GWP makes different greenhouse gases comparable with regard to their "effectiveness in causing radiative forcing".[1]: 2232 It is expressed as a multiple of the radiation that would be absorbed by the same mass of added carbon dioxide (CO2), which is taken as a reference gas. Therefore, the GWP has a value of 1 for CO2. For other gases it depends on how strongly the gas absorbs infrared thermal radiation, how quickly the gas leaves the atmosphere, and the time frame being considered.
For example, methane has a GWP over 20 years (GWP-20) of 81.2[2] meaning that, for example, a leak of a tonne of methane is equivalent to emitting 81.2 tonnes of carbon dioxide measured over 20 years. As methane has a much shorter atmospheric lifetime than carbon dioxide, its GWP is much less over longer time periods, with a GWP-100 of 27.9 and a GWP-500 of 7.95.[2]: 7SM-24
The carbon dioxide equivalent (CO2e or CO2eq or CO2-e or CO2-eq) can be calculated from the GWP. For any gas, it is the mass of CO2 that would warm the earth as much as the mass of that gas. Thus it provides a common scale for measuring the climate effects of different gases. It is calculated as GWP times mass of the other gas.
Definition
The global warming potential (GWP) is defined as an "index measuring the radiative forcing following an emission of a unit mass of a given substance, accumulated over a chosen time horizon, relative to that of the reference substance, carbon dioxide (CO2). The GWP thus represents the combined effect of the differing times these substances remain in the atmosphere and their effectiveness in causing radiative forcing."[1]: 2232
In turn, radiative forcing is a scientific concept used to quantify and compare the external drivers of change to Earth's energy balance.[3]: 1–4 Radiative forcing is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured in watts per meter squared.[4]
Values
.png)
The global warming potential (GWP) depends on both the efficiency of the molecule as a greenhouse gas and its atmospheric lifetime. GWP is measured relative to the same mass of CO2 and evaluated for a specific timescale.[6] Thus, if a gas has a high (positive) radiative forcing but also a short lifetime, it will have a large GWP on a 20-year scale but a small one on a 100-year scale. Conversely, if a molecule has a longer atmospheric lifetime than CO2 its GWP will increase when the timescale is considered. Carbon dioxide is defined to have a GWP of 1 over all time periods.
Methane has an atmospheric lifetime of 12 ± 2 years.[7]: Table 7.15 The 2021 IPCC report lists the GWP as 83 over a time scale of 20 years, 30 over 100 years and 10 over 500 years.[7]: Table 7.15 A 2014 analysis, however, states that although methane's initial impact is about 100 times greater than that of CO2, because of the shorter atmospheric lifetime, after six or seven decades, the impact of the two gases is about equal, and from then on methane's relative role continues to decline.[8] The decrease in GWP at longer times is because methane decomposes to water and CO2 through chemical reactions in the atmosphere. Similarly the third most important GHG, nitrous oxide (N2O), is a common gas emitted through the denitrification part of the nitrogen cycle.[9] It has a lifetime of 109 years and an even higher GWP level running at 273 over 20 and 100 years.
Examples of the atmospheric lifetime and GWP relative to CO2 for several greenhouse gases are given in the following table:
| Gas name | Chemical
formula |
Lifetime | Radiative Efficiency | Global warming potential (GWP) for given time horizon | ||
|---|---|---|---|---|---|---|
| 20-yr.[7]: Table 7.15 [10] | 100-yr.[7]: Table 7.15 [10] | 500-yr.[7]: Table 7.15 [11] | ||||
| Carbon dioxide | CO2 | (A) | 1.37×10−5 | 1 | 1 | 1 |
| Methane (fossil) | CH 4 |
12 | 5.7×10−4 | 83 | 30 | 10 |
| Methane (non-fossil) | CH 4 |
12 | 5.7×10−4 | 81 | 27 | 7.3 |
| Nitrous oxide | N 2O |
109 | 3×10−3 | 273 | 273 | 130 |
| CFC-11 | CCl 3F |
52 | 0.29 | 8 321 | 6 226 | 2 093 |
| CFC-12 | CCl 2F 2 |
100 | 0.32 | 10 800 | 10 200 | 5 200 |
| HCFC-22 | CHClF 2 |
12 | 0.21 | 5 280 | 1 760 | 549 |
| HFC-32 | CH 2F 2 |
5 | 0.11 | 2 693 | 771 | 220 |
| HFC-134a | CH 2FCF 3 |
14 | 0.17 | 4 144 | 1 526 | 436 |
| Tetrafluoromethane | CF 4 |
50 000 | 0.09 | 5 301 | 7 380 | 10 587 |
| Hexafluoroethane | C 2F 6 |
10 000 | 0.25 | 8 210 | 11 100 | 18 200 |
| Sulfur hexafluoride | SF 6 |
3 200 | 0.57 | 17 500 | 23 500 | 32 600 |
| Nitrogen trifluoride | NF 3 |
500 | 0.20 | 12 800 | 16 100 | 20 700 |
| (A) No single lifetime for atmospheric CO2 can be given. | ||||||
Estimates of GWP values over 20, 100 and 500 years are periodically compiled and revised in reports from the Intergovernmental Panel on Climate Change. The most recent report is the IPCC Sixth Assessment Report (Working Group I) from 2023.[7]
The IPCC lists many other substances not shown here.[12][7] Some have high GWP but only a low concentration in the atmosphere.
The values given in the table assume the same mass of compound is analyzed; different ratios will result from the conversion of one substance to another. For instance, burning methane to carbon dioxide would reduce the global warming impact, but by a smaller factor than 25:1 because the mass of methane burned is less than the mass of carbon dioxide released (ratio 1:2.74).[13] For a starting amount of 1 tonne of methane, which has a GWP of 25, after combustion there would be 2.74 tonnes of CO2, each tonne of which has a GWP of 1. This is a net reduction of 22.26 tonnes of GWP, reducing the global warming effect by a ratio of 25:2.74 (approximately 9 times).
| Greenhouse gas | Lifetime (years) |
Global warming potential, GWP | ||
|---|---|---|---|---|
| 20 years | 100 years | 500 years | ||
| Hydrogen (H2) | 4–7[14] | 33 (20-44)[14] | 11 (6–16)[14] | — |
| Methane (CH4) | 11.8[7] | 56[15] 72[16] 84 / 86f[12] 96[17] 80.8 (biogenic)[7] 82.5 (fossil)[7] |
21[15] 25[16] 28 / 34f[12] 32[18] 39 (biogenic)[19] 40 (fossil)[19] |
6.5[15] 7.6[16] |
| Nitrous oxide (N2O) | 109[7] | 280[15] 289[16] 264 / 268f[12] 273[7] |
310[15] 298[16] 265 / 298f[12] 273[7] |
170[15] 153[16] 130[7] |
| HFC-134a (hydrofluorocarbon) | 14.0[7] | 3,710 / 3,790f[12] 4,144[7] |
1,300 / 1,550f[12] 1,526[7] |
435[16] 436[7] |
| CFC-11 (chlorofluorocarbon) | 52.0[7] | 6,900 / 7,020f[12] 8,321[7] |
4,660 / 5,350f[12] 6,226[7] |
1,620[16] 2,093[7] |
| Carbon tetrafluoride (CF4 / PFC-14) | 50,000[7] | 4,880 / 4,950f[12] 5,301[7] |
6,630 / 7,350f[12] 7,380[7] |
11,200[16] 10,587[7] |
| HFC-23 (hydrofluorocarbon) | 222[12] | 12,000[16] 10,800[12] |
14,800[16] 12,400[12] |
12,200[16] |
| Sulfur hexafluoride SF6 | 3,200[12] | 16,300[16] 17,500[12] |
22,800[16] 23,500[12] |
32,600[16] |
Earlier values from 2007
The values provided in the table below are from 2007 when they were published in the IPCC Fourth Assessment Report.[20][16] These values are still used (as of 2020) for some comparisons.[21]
| Greenhouse gas | Chemical formula | 100-year Global warming potentials (2007 estimates, for 2013–2020 comparisons) |
|---|---|---|
| Carbon dioxide | CO2 | 1 |
| Methane | CH4 | 25 |
| Nitrous oxide | N2O | 298 |
| Hydrofluorocarbons (HFCs) | ||
| HFC-23 | CHF3 | 14,800 |
| Difluoromethane (HFC-32) | CH2F2 | 675 |
| Fluoromethane (HFC-41) | CH3F | 92 |
| HFC-43-10mee | CF3CHFCHFCF2CF3 | 1,640 |
| Pentafluoroethane (HFC-125) | C2HF5 | 3,500 |
| HFC-134 | C2H2F4 (CHF2CHF2) | 1,100 |
| 1,1,1,2-Tetrafluoroethane (HFC-134a) | C2H2F4 (CH2FCF3) | 1,430 |
| HFC-143 | C2H3F3 (CHF2CH2F) | 353 |
| 1,1,1-Trifluoroethane (HFC-143a) | C2H3F3 (CF3CH3) | 4,470 |
| HFC-152 | CH2FCH2F | 53 |
| HFC-152a | C2H4F2 (CH3CHF2) | 124 |
| HFC-161 | CH3CH2F | 12 |
| 1,1,1,2,3,3,3-Heptafluoropropane (HFC-227ea) | C3HF7 | 3,220 |
| HFC-236cb | CH2FCF2CF3 | 1,340 |
| HFC-236ea | CHF2CHFCF3 | 1,370 |
| HFC-236fa | C3H2F6 | 9,810 |
| HFC-245ca | C3H3F5 | 693 |
| HFC-245fa | CHF2CH2CF3 | 1,030 |
| HFC-365mfc | CH3CF2CH2CF3 | 794 |
| Perfluorocarbons | ||
| Carbon tetrafluoride – PFC-14 | CF4 | 7,390 |
| Hexafluoroethane – PFC-116 | C2F6 | 12,200 |
| Octafluoropropane – PFC-218 | C3F8 | 8,830 |
| Perfluorobutane – PFC-3-1-10 | C4F10 | 8,860 |
| Octafluorocyclobutane – PFC-318 | c-C4F8 | 10,300 |
| Perfluouropentane – PFC-4-1-12 | C5F12 | 9,160 |
| Perfluorohexane – PFC-5-1-14 | C6F14 | 9,300 |
| Perfluorodecalin – PFC-9-1-18b | C10F18 | 7,500 |
| Perfluorocyclopropane | c-C3F6 | 17,340 |
| Sulfur hexafluoride (SF6) | ||
| Sulfur hexafluoride | SF6 | 22,800 |
| Nitrogen trifluoride (NF3) | ||
| Nitrogen trifluoride | NF3 | 17,200 |
| Fluorinated ethers | ||
| HFE-125 | CHF2OCF3 | 14,900 |
| Bis(difluoromethyl) ether (HFE-134) | CHF2OCHF2 | 6,320 |
| HFE-143a | CH3OCF3 | 756 |
| HCFE-235da2 | CHF2OCHClCF3 | 350 |
| HFE-245cb2 | CH3OCF2CF3 | 708 |
| HFE-245fa2 | CHF2OCH2CF3 | 659 |
| HFE-254cb2 | CH3OCF2CHF2 | 359 |
| HFE-347mcc3 | CH3OCF2CF2CF3 | 575 |
| HFE-347pcf2 | CHF2CF2OCH2CF3 | 580 |
| HFE-356pcc3 | CH3OCF2CF2CHF2 | 110 |
| HFE-449sl (HFE-7100) | C4F9OCH3 | 297 |
| HFE-569sf2 (HFE-7200) | C4F9OC2H5 | 59 |
| HFE-43-10pccc124 (H-Galden 1040x) | CHF2OCF2OC2F4OCHF2 | 1,870 |
| HFE-236ca12 (HG-10) | CHF2OCF2OCHF2 | 2,800 |
| HFE-338pcc13 (HG-01) | CHF2OCF2CF2OCHF2 | 1,500 |
| (CF3)2CFOCH3 | 343 | |
| CF3CF2CH2OH | 42 | |
| (CF3)2CHOH | Zdroj:https://en.wikipedia.org?pojem=CO2_equivalent||