Global warming (or climate change) is caused by a build-up of carbon dioxide and other greenhouse gases in our atmosphere. The gases trap heat by forming a blanket around the Earth – like the glass of a greenhouse. These gases stay in the atmosphere for many years. And as they build up, the planet’s temperature rises.
A warmer world leads to a more extreme climate – with more severe droughts, floods and storms. And as the world warms up, feedback-loops can accelerate warming: melting polar ice means less of the sun’s heat is reflected back into space.
Greenhouse gases build up in the atmosphere mainly due to the burning of fossil fuels – coal, oil and gas – and by cutting down forests. Greenhouse-gas levels have rocketed in the last 100 years.