WWF - For a living planet

When the atmosphere warms up, so do the world's oceans - causing many dramatic impacts.

One obvious impact is that warming seas are having a terrible effect on the world's coral reefs. These reefs are effectively the rainforests of the seas, with a staggering array of different types of fish and other marine animals living in and around them.

But coral is a living organism, and it is extremely sensitive to changes in temperature. As the world's oceans increase in temperature, the coral reefs are bleaching and dying. It is estimated that if the global rise in temperature is not stopped there will be just 5% of Australia's Great Barrier Reef - the world's largest coral reef - left by 2050.

But this is not just an environmental tragedy as coral reefs provide enormous quantities of food for humanity. Around half a billion people - a twelfth of the entire population of the world - relies on fish from coral reefs as their main source of protein. If the reefs are destroyed, so is this vital larder for the planet.