The Earth is getting warmer. Average temperatures worldwide have risen during the last century and there is no sign of this rise slowing. There is now a high risk that the ice sheets on Greenland and Antarctica will start to melt, raising sea levels everywhere and changing world climates.

Greenhouse effect

The atmosphere contains gases that stop all the Sun’s heat escaping. These gases act like the glass in a greenhouse. They help keep the Earth’s surface warm. This is called the greenhouse effect.

​​​​​​​Global warming is caused by the greenhouse effect. Human activities have resulted in a large increase of greenhouse gases, such as carbon dioxide, in the atmosphere.

If melting ice causes sea levels to rise, many coastal cities could be flooded by seawater. Some low-lying islands, such as the Maldives, may disappear altogether. There are other likely consequences, too: more frequent droughts, violent storms, the oceans turning more acidic (destroying coral reefs), the extinction of many animal species, failing harvests. To avoid this catastrophe, we must reduce the amount of greenhouse gases in the air by burning fewer fossil fuels.