Mass extinction predicted in heat

If two degrees is generally accepted as the threshold of dangerous climate change, it is clear that a rise of six degrees in global average temperatures must be very dangerous indeed.

Just how dangerous was signalled in 2007 by science writer Mark Lynas, who combed all the available scientific research to construct a picture of a world with temperatures three times higher than the danger limit.

He concluded a rise in temperatures of this magnitude "would catapult the planet into an extreme greenhouse state not seen for nearly 100 million years, when dinosaurs grazed on polar rainforests and deserts reached into the heart of Europe".

He said: "It would cause a mass extinction of almost all life and probably reduce humanity to a few struggling groups of embattled survivors clinging to life near the poles."

Very few species could adapt in time to the abruptness of the transition, he said. "With the tropics too hot to grow crops, and the subtropics too dry, billions of people would find themselves in areas of the planet which are essentially uninhabitable.

"As the ice-caps melt, hundreds of millions will also be forced to move inland due to rapidly rising seas. As world food supplies crash, the higher mid-latitude and subpolar regions would become fiercely contested refuges."

- INDEPENDENT