Defra: expect 4C global warming

Defra's chief scientist says the country should prepare for a 4C rise in average global temperatures, despite an EU committment to ensure climate change causes no more than a 2C rise. Speaking about the EU policy, Professor Bob Watson said: "Given this is an ambitious target, and we don't know in detail how to limit greenhouse gas emissions to realise a 2 degree target, we should be prepared to adapt to 4C."

Professor Watson was backed by the Government's former chief scientist, Sir David King, who said: "Even if we get the best possible global agreement to reduce greenhouse gasses on any rational basis you should be preparing for a 20% risk [of temperatures increasing by more than 3.5C] so I think Bob Watson is quite right."

A 4C temperature rise would have a catastrophic impact across the world, with between 7 and 300m people affected by coastal flooding and 20 to 50% of species made extinct.