The 'Hockey Stick' graph which shows a sharp upturn in temperatures in recent decades with the Earth hotter in the late 20th Century than it has been in the last 1000 years.

What causes global warming?

Global warming or climate change is caused by increased levels of carbon dioxide (C0₂) and other polluting gases in our atmosphere.

Heat from the Sun a)
is trapped by the
gases in our atmosphere b)

The gases trap heat by forming a blanket around the Earth - like the glass of a greenhouse.

Once released the greenhouse gases stay in the atmosphere for many years. As they build up, the planet's temperature rises.

Greenhouse gases are released by burning fossil fuels - coal, oil and gas - and by cutting down forests.