What are the greenhouse gases?

The principal greenhouse gases are:

• Carbon dioxide (also known as CO2 – this is the main greenhouse gas in terms of the amount in the earth’s atmosphere.)
• Water vapour (H2O).
• Methane (CH4).
• Nitrous oxide (N2O).
• Chlorofluorocarbons (CFCs).
• Ozone (O3 ).

Other greenhouse gases include some solvents and the air pollutants resulting from the burning of fossil fuels to run cars and equipment.

All gases can be weighed. One kilogram of carbon dioxide would fill a large family fridge. One tonne of carbon dioxide would fill a family home. Carbon dioxide is colourless and odourless so it cannot be seen or smelt.

Some greenhouse gases are stronger heat absorbers than others. For example, 1kg of methane captures as much heat as 21kg of carbon dioxide. And only 1kg of nitrous oxide captures as much heat as 310kg of carbon dioxide.

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