Greenhouse gases
'Greenhouse gas' is an umbrella term to describe invisible gases, some are found naturally in the atmosphere like carbon dioxide, some are manufactured like hydrofluorocarbons.
All are transparent to solar radiation (light), but opaque to longwave radiation (infrared heat). Their action is similar to that of glass in a greenhouse. In total there are about 30 greenhouse gases in the atmosphere.
- carbon dioxide (CO2)
- methane (CH4)
- nitrous oxide (N2O)
- hydrofluorocarbons (HCFs)
- perfluorocarbons (PFCs)
- sulphur hexafluoride (SF6)
While some of these occur naturally, such as the first two in the list above, they are also emitted as a result of burning fossil fuels and the decomposition of wastes. Nitrous oxides are emitted in vehicle exhaust fumes and the fluorocarbons are used in refrigerants.
Methane is around twenty times more potent than CO2 as a greenhouse gas but much less is emitted along with other gases in the list above. You will often find the terms carbon emissions and greenhouse gas emissions used almost synonymously. This is because carbon dioxide is one of the most important greenhouse gases creating the biggest impact.
To see more information on how much CO2 we are emitting, visit the what we are emitting now page.