From the Guardian:
Global temperatures will rise by an average of 3C due to climate change and cause catastrophic damage around the world unless governments take urgent action, according to the UK government’s chief scientist.
In a stark warning issued yesterday Sir David King said that a rise of this magnitude would cause famine and drought and threaten millions of lives.
It would also cause a worldwide drop in cereal crops of between 20 and 400m tonnes, put 400 million more people at risk of hunger, and put up to 3 billion people at risk of flooding and without access to fresh water supplies.
Here.