Four degrees of preparation

• James Randerson, London
• The Age, August 8, 2008
• http://www.theage.com.au/world/four-degrees-of-preparation-20080807-3rqz.html

BRITAIN should prepare for dangerous climate change of perhaps 4 degrees, according to one Government adviser.

In policy areas such as flood protection, agriculture and coastal erosion, Professor Bob Watson said the country should plan for the effects of a 4-degree global average rise on pre-industrial levels. The European Union is committed to limiting emissions globally so that temperatures do not rise more than 2 degrees.

"There is no doubt that we should aim to limit changes in the global mean surface temperature to 2 degrees," said Professor Watson, the chief scientific adviser to the British Department for the Environment, Food and Rural Affairs.

"But 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 4 degrees."

Professor Watson's stance was backed by the former chief scientific adviser, Sir David King. He said that even by restricting carbon dioxide levels in the atmosphere at below 450 parts per million, there was a 50% probability that temperature rises would exceed 2 degrees and a 20% probability that they would exceed 3.5 degrees.

"I think Bob Watson is quite right to put up the figure of 4 degrees," Sir David said.

Such a rise would have a catastrophic impact. Britain would encounter rising sea levels and inland flooding.

Sir David said a 2½-year analysis by the Government's Foresight program on the implications for coastal defences had more impact in cabinet than any other research on the effects of climate change that he presented.

"We begin to have to talk about ordered retreat from some areas of Britain because it becomes impossible to defend," he said.

Other experts were concerned that Professor Watson's comments might be seen as defeatist.

GUARDIAN