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CO2 equivalents


Most charts and tables in this emissions section of our website convert all greenhouse gase emissions (GHG) into CO2 equivalents so they can be compared.

Each greenhouse gas (GHG) has a different global warming potential (GWP) and persists for a different length of time in the atmosphere. The three gases of carbon dioxide (CO2), methane (NH4), and nitrous oxide (N2O) (along with water vapour) are the main greenhouse gases:

  • carbon dioxide (CO2) - 1 x
  • methane (NH4)          - 21 x
  • nitrous oxide (N2O)    - 310 x


The greenhouse effect of methane is 21 times more powerful than carbon dioxide. Nitrous oxide is 310 times more powerful than carbon dioxide. (1)


Water vapour is not considered to be a cause of man-made global warming because it does not persist in the atmosphere for more than a few days.

There are other greenhouse gases which have far greater global warming potential (GWP) but are much less prevalent. These are sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs).

There are a wide variety of uses for SF6, HFCs, and PFCs but they have been most commonly used as refrigerants and for fire suppression. Many of these compounds also have a depleting effect on ozone in the upper atmosphere.

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GWP table



The following table shows the global warming potentials (GWP) for all of the greenhouse gases reported by the United Nations Framework Convention on Climate Change (UNFCCC) .

Greenhouse Gas Formula 100 year GWP
1. Carbon dioxide CO2 1
2. Methane CH4 21
3. Nitrous oxide N2O 310
4. Sulphur hexafluoride SF6 23,900
  Hydrofluorocarbons (HFCs)
5. HFC-23 CHF3 11,700
6. HFC-32 CH2F2 650
7. HFC-41 CH3F 150
8. HFC-43-10mee C5H2F10 1,300
9. HFC-125 C2HF5 2,800
10. HFC-134 C2H2F4
(Structure: CHF
2CHF2)
1,000
11. HFC-134a C2H2F4
(Structure: CH
2FCF3)
1,300
12. HFC-143 C2H3F3
(Structure: CHF
2CH2F)
300
13. HFC-143a C2H3F3
(Structure: CF
3CH3)
3,800
14. HFC-152a C2H4F2
(Structure: CH
3CHF2)
140
15. HFC-227ea C3HF7 2,900
16. HFC-236fa C3H2F6 6,300
17. HFC-245ca C3H3F5 560
  Perfluorocarbons (PFCs)
18. Perfluoromethane CF4 6,500
19. Perfluoroethane C2F6 9,200
20. Perfluoropropane C3F8 7,000
21. Perfluorobutane C4F10 7,000
22. Perfluorocyclobutane c-C4F8 8,700
23. Perfluoropentane C5F12 7,500
24. Perfluorohexane C6F14 7,400