This is all a big mistake, according to Lord Stern, who completed a review of the economics of climate change for Tony Blair in what now seems the different world of 2006.

The record rainfall and storm surges that have brought flooding across the UK are a clear sign that we are already experiencing the impacts of climate change. There are powerful grounds for arguing that this is part of a trend.

Stern says things have moved on in the eight years since his review. "I would have been much fiercer", he says. "Emissions have gone up faster than I thought and some of the effects of global warming are coming through more quickly, such as melting of the glaciers and the polar ice caps. But technical change has been faster too."

Stern says that on present trends global temperatures will be 4-5C higher in the next century and governments are fooling themselves if they think this will only have a modest impact on their economies.

"The last time we had a change in global temperatures of this order of magnitude it was in the other direction. It was called the Ice Age."