How do greenhouse gases cause climate change?

Greenhouse gases normally just keep the planet warm. But when man started adding extra greenhouse gases (carbon dioxide, methane and CFCs) the atmosphere started heating up.

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Greenhouse gases are any gases in the atmosphere with three or more atoms. They catch the sun's heat as it is being radiated out from the warm earth and stop some of it going back out into space. This is called the greenhouse effect and it has been going on for millions of years.

Recently (well, since about 1750), at the start of the Industrial Age, humans discovered coal, and later oil and natural gas. We burned these fossil fuels to drive industry, transport and to generate electricity. When burnt, these fuels release the carbon that had been trapped for 300 million years. So for 250 years we have been pumping extra carbon dioxide (CO2) into the atmosphere, adding to the usual amount (280 parts per million or ppm). The concentration of CO2 is now around 390 ppm, a 40% increase. There have been other greenhouse gases that we are responsible for adding, mainly methane, nitrous oxide and CFCs.

All these extra greenhouse gases absorb more and more heat and are causing global warming. Global warming causes climate change, which means some areas will flood, others will have drought, weather events like storms may become more frequent and more severe and rising sea level may cause coastal damage and flooding.