Charities' 2C fears.

UP to four billion people will face water shortages if temperatures rise more than 2C, aid agencies warned yesterday.

In a report they also predict 250 million people will run short of food unless governments agree to cut greenhouse gas emissions.

The agencies said failure to agree at this week's G8 summit in Germany could be catastrophic in future.

The report, 2 Degrees One Chance, was by Tearfund, Oxfam, Christian Aid and Practical Action.

Antonio Hill at Oxfam said: "The world cannot afford the G8 to come up with more rhetoric that is not backed by action."