Things are worse than expected!
A Sudden Change of State by George Monbiot

A new paper suggests we have been greatly underestimating the impacts of climate change – and the size of the necessary response.
By George Monbiot. Published in the Guardian 3rd July 2007
Reading a scientific paper on the train this weekend, I found, to my amazement, that my hands were shaking. This has never happened to me before, but nor have I ever read anything like it. Published by a team led by James Hansen at Nasa, it suggests that the grim reports issued by the Intergovernmental Panel on Climate Change could be absurdly optimistic(1).
The IPCC predicts that sea levels could rise by as much as 59cm this century(2). Hansen’s paper argues that the slow melting of ice sheets the panel expects doesn’t fit the data. The geological record suggests that ice at the poles does not melt in a gradual and linear fashion, but flips suddenly from one state to another. When temperatures increased to 2-3 degrees above today’s level 3.5 million years ago, sea levels rose not by 59 centimetres but by 25 metres. The ice responded immediately to changes in temperature(3).

See the rest of the article here:
http://www.monbiot.com/archives/2007/07/03/a-sudden-change-of-state/