From EnviroWiki
Greenhouse gases
When talking about greenhouse gases, customarily we refer only to CO2 (carbon dioxide). This is because over 70 per cent of all emissions are CO2. Worryingly though, CO2 is one of the least damaging greenhouse gases. There are many with much more potential for harm and with longer lifetimes.
Greenhouse gases differ in their ability to trap heat in the atmosphere. For example, CO2 (carbon dioxide) has the least ability to trap gases, while SF6 (Sulphur Hexafluoride) has the greatest.
This ability of greenhouse gases to trap heat is termed its Global Warming Potential (GWP).
The GWP (of a greenhouse gas) is a relative scale that compares the gas in question to that of the equivalent mass of carbon dioxide. Carbon dioxide, by definition, has the GWP of 1. A GWP is calculated over a specific time interval.
The warming potential of the other greenhouse gases is provided on the table below.
| Name | Symbol | Lifetime (years) | Global Warming Potential | ||
|---|---|---|---|---|---|
| 20 yrs | 100 yrs | 500 yrs | |||
| Carbon Dioxide | CO2 | 1 | 1 | 1 | |
| Methane | CH4 | 12.0 | 62 | 23 | 7 |
| Nitrous Oxide | N2O | 114 | 275 | 296 | 156 |
| HFC - 23 | CHF3 | 260 | 9400 | 12000 | 10000 |
| HFC - 32 | CH2F2 | 5.0 | 1800 | 550 | 170 |
| HFC - 41 | CH3F | 2.6 | 330 | 97 | 30 |
| HFC - 125 | CHF2CF3 | 29 | 5900 | 3400 | 1100 |
| HFC - 134 | CHF2CHF2 | 9.6 | 3200 | 1100 | 330 |
| HFC - 134a | CH2FCF2 | 13.8 | 3300 | 1300 | 400 |
| HFC - 143 | CHF2CH2F | 3.4 | 1100 | 330 | 100 |
| HFC - 143a | CF3CH3 | 52 | 5500 | 4300 | 1600 |
| HFC - 152 | CH2FCH2F | 0.5 | 140 | 43 | 13 |
| HFC - 152a | CH3CHF2 | 1.4 | 410 | 120 | 37 |
| HFC - 227ea | CF3CHFCF3 | 33.0 | 5600 | 3500 | 1100 |
| HFC - 236fa | CF3CH2CF3 | 220 | 7500 | 9400 | 7100 |
| HFC - 245ca | CH2FCF2CHF2 | 5.9 | 2100 | 640 | 200 |
| HFC - 43 -l0mee | CF3CHFCHFCF2CF3 | 15 | 3700 | 1500 | 470 |
| Perfluorobutane | C4F10 | 2600 | 5900 | 8600 | 12400 |
| Perfluoromethane | CF4 | 50000 | 3900 | 5700 | 8900 |
| Perfluoropropane | C3F8 | 2600 | 5900 | 8600 | 12400 |
| Perfluoropentane | C5F12 | 4100 | 6000 | 8900 | 13200 |
| Perfluoroethane | C2F6 | 10000 | 8000 | 11900 | 18000 |
| Perfluorohexane | C6F14 | 3200 | 6100 | 9000 | 13200 |
| Sulphur Hexafluoride | SF6 | 3200 | 15100 | 22200 | 32400 |
