The climate is different from the weather. It is the average weather we experience over a long period of time. This includes temperature, wind and rainfall patterns.
The climate of the earth is always changing. These changes are due to natural causes, the effects of the sun, land, oceans and atmosphere.
Humans are changing current climate through the production of greenhouse gases in the atmosphere such as carbon dioxide (CO2), methane and nitrous oxide. In 2004, CO2 made up 85% of the UK’s greenhouse gases released into the atmosphere.
Greenhouse gases remain in the atmosphere for long periods, and act as a 'blanket' around the earth absorbing the infra-red radiation from the earth and radiating it back to warm the lower atmosphere – the greenhouse effect. Without this effect the earth’s temperature would be 20 to 30°C colder and less suitable for life. Carbon dioxide occurs in the atmosphere naturally. The introduction of more CO2 by humans increases greenhouse gases and leads to more heat being trapped and global warming.
Most scientists now agree that it is humans that are causing higher levels of CO2 to be released into the atmosphere.
6.5 billion tonnes of CO2 is released into the earth's atmosphere each year through human activities. 2% is released by the UK. (Source: Defra)
Next: Where's the evidence?