Greenhouse gases (GHGs), such as carbon dioxide (CO2), absorb the sun's warmth, heating the atmosphere. This warm layer of air around the planet acts like a blanket, and is essential for life.
However, rapid changes in the levels of GHGs – and subsequent rapid changes in the average annual temperature – can lead to more chaotic weather patterns, with extreme events such as hurricanes, droughts and floods increasingly common.
In order of their effect on the climate, the most important GHGs are:
- Water vapour, which causes 36-70% of the greenhouse effect on Earth
- Carbon dioxide, which causes 9-26%
- Methane, which causes 4-9%
- Ozone, which causes 3-7%
There are other important GHGs, including nitrous oxide (an important emission from agriculture) and chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs). Some GHGs exert far more powerful climate forcing effects, many thousands of times more potently than CO2. While the sheer volume of CO2 being released is the main reason for the apparent focus on carbon, other emissions sources should not be neglected.
Tackling climate change requires a comprehensive range of activity that includes emissions reduction at source, increased efficiency of essential fossil fuel use, and mitigation of GHG impacts through activities such as woodland creation.
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