Global warming potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, relative to carbon dioxide (CO2). It is expressed as a multiple of warming caused by the same mass of (CO2). Therefore, by definition CO2 has a GWP of 1. For other gases it depends on how strongly the gas absorbs thermal radiation, how quickly the gas leaves the atmosphere, and the time frame considered.
For example, methane has a GWP over 20 years (GWP-20) of 81.2meaning that, 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.
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.
The Technology Transitions Rule specified global warming potential (GWP) values of common substitutes for purposes of implementing this rule. These values are listed in 40 CFR 84.64 and are provided here as reference. Also provided here are the GWPs of a subset of hydrofluorocarbons (HFCs) and blends calculated using the methodology discussed in the rule.
Global Warming Potentials for HFCs, HFC Blends, and Substitutes
Substance Name | 100-Year Global Warming Potential | Reference |
2-chloropropane | 1 | WMO 2022 |
Acetone | 0.5 | IPCC 2007 |
Acetone/isopentane blend | 1 | Calculated |
Blends of 10% to 90% HFO-1234ze(E) by weight and the remainder HCFO-1233zd(E) | 1.3–3.7 | Calculated |
Blends of 10% to 90% HFO-1234ze(E) by weight and the remainder HFC-152a | 13–112 | Calculated |
Blends of 10% to 99% HFO-1336mzz(Z) by weight and the remainder HFC-152a | 3–112 | Calculated |
Blends of 0% to 100% HFO-1234ze(E), 0% to 70% methyl formate, 0% to 60% HFC-152a, 0% to 60% carbon dioxide, 0% to 60% water | 1-80 | Calculated |
Dimethyl ether | 1 | IPCC 2007 |
HCFO-1233zd(Z) | 1 | Calculated |
HCFO-1224yd(Z) | 1 | EPA 2023 |
HCFO-1233yd(Z) | 1 | SNAP 2022 |
HCFO-1233zd(E) | 4 | WMO 2022 |
HFC-134a | 1,430 | IPCC 2007 |
HFC-143a | 4,470 | IPCC 2007 |
HFC-152a | 124 | IPCC 2007 |
HFC-23 | 14,800 | IPCC 2007 |
HFC-245fa | 1,030 | IPCC 2007 |
HFC-32 | 675 | IPCC 2007 |
HFC-365mfc | 794 | IPCC 2007 |
| HFE-347pcf2 | 987 | IPCC 2007 |
| HFE-449s1 (HFE-7100) | 297 | IPCC 2007 |
HFE-569sf2 | 59 | IPCC 2007 |
HFO-1234yf | 1 | WMO 2022 |
HFO-1234ze(E) | 1 | WMO 2022 |
HFO-1336mzz(E) | 26 | WMO 2022 |
HFO-1336mzz(Z) | 2 | WMO 2022 |
Hydrocarbons (C5-C20) | 1-2.7 | IPCC 2007 and WMO 2022 |
Methoxytridecafluoroheptane (MPHE) isomers | 2.5 | SNAP 2015 |
Methyl formate | 13 | WMO 2022 |
Methylal (dimethoxymethane) | 1 | WMO 2022 |
Oxygenated organic solvents (esters, ethers, alcohols, ketones) | 1-13 | IPCC 2007 and WMO 2022 |
R-170 (ethane) | 5.5 | IPCC 2007 |
R-290 (propane) | 3.3 | IPCC 2007 |
R-404A | 3,922 | Calculated |
R-407C | 1,774 | Calculated |
R-410A | 2,088 | Calculated |
R-441A | 3 | Calculated |
R-448A | 1,386 | Calculated |
R-449A | 1,396 | Calculated |
R-449B | 1,411 | Calculated |
R-450A | 601 | Calculated |
R-451A | 147 | Calculated |
R-452A | 2,140 | Calculated |
R-452B | 698 | Calculated |
R-454A | 237 | Calculated |
R-454B | 465 | Calculated |
R-454C | 146 | Calculated |
R-455A | 146 | Calculated |
R-456A | 684 | Calculated |
R-457A | 137 | Calculated |
R-457B | 249 | Calculated |
R-471A | 144 | Calculated |
R-476A | 147 | Calculated |
R-480A | 291 | Calculated |
R-482A | 144 | Calculated |
R-507A | 3,985 | Calculated |
R-508B | 13,396 | Calculated |
R-513A | 630 | Calculated |
R-513B | 594 | Calculated |
R-514A | 3 | Calculated |
R-515B | 287 | Calculated |
R-516A | 140 | Calculated |
R-600 (butane) | 4 | IPCC 2007 |
R-600a (isobutane) | 1 | WMO 2022 |
R-717 (ammonia) | 1 | WMO 2022 |
R-744 (carbon dioxide) | 1 | IPCC 2007 |
| R-1150 (ethylene) | 3.7 | IPCC 2007 |
| R-1270 (propylene) | 1.8 | IPCC 2007 |
Saturated light hydrocarbons (C3-C6) | 1-4 | IPCC 2007 and WMO 2022 |
Trans-1,2-dichloroethylene (HCO-1130(E)) | 5 | EPA 2023 |