The world is likely to suffer a temperature rise of more than 3C, the government's chief scientist warned [UK government - adam].

That would put up to 400 million people worldwide at risk of hunger, said Professor Sir David King in a report based on computer predictions.

He told the BBC the world had to act now to tackle global warming expected to happen over the next 100 years.

He said even if international agreement could be reached on limiting emissions, climate change was inevitable.

The UK Government and the EU want to stabilise the climate at an increase of no more than 2C, but the US refuses to cut emissions and those of India and China are rising quickly.