Climate: Bjørn Lomborg: $100bn a Year Needed to Fight Climate Change

The world's most high-profile climate change sceptic is to declare that global warming is "undoubtedly one of the chief concerns facing the world today" and "a challenge humanity must confront", in an apparent U-turn that will give a huge boost to the embattled environmental lobby.

Bjørn Lomborg, the self-styled "sceptical environmentalist" once compared to Adolf Hitler by the UN's climate chief, is famous for attacking climate scientists, campaigners, the media and others for exaggerating the rate of global warming and its effects on humans, and the costly waste of policies to stop the problem.

But in a new book to be published next month, Lomborg will call for tens of billions of dollars a year to be invested in tackling climate change. "Investing $100bn annually would mean that we could essentially resolve the climate change problem by the end of this century," the book concludes.

Lomborg denies he has performed a volte face, pointing out that even in his first book he accepted the existence of man-made global warming. "The point I've always been making is it's not the end of the world," he told the Guardian. "That's why we should be measuring up to what everybody else says, which is we should be spending our money well."

But he said the crucial turning point in his argument was the Copenhagen Consensus project, in which a group of economists were asked to consider how best to spend $50bn. The first results, in 2004, put global warming near the bottom of the list, arguing instead for policies such as fighting malaria and HIV/Aids. But a repeat analysis in 2008 included new ideas for reducing the temperature rise, some of which emerged about halfway up the ranking. Lomborg said he then decided to consider a much wider variety of policies to reduce global warming, "so it wouldn't end up at the bottom".

The difference was made by examining not just the dominant international policy to cut carbon emissions, but also seven other "solutions" including more investment in technology, climate engineering, and planting more trees and reducing soot and methane, also significant contributors to climate change, said Lomborg.

"If the world is going to spend hundreds of millions to treat climate, where could you get the most bang for your buck?" was the question posed, he added. After the analyses, five economists were asked to rank the 15 possible policies which emerged. Current policies to cut carbon emissions through taxes - of which Lomborg has long been critical - were ranked largely at the bottom of four of the lists. At the top were more direct public investment in research and development rather than spending money on low carbon energy now, and climate engineering.

For more, see Bjørn Lomborg: $100bn a Year Needed to Fight Climate Change by Juliette Jowit, August 30, 2010, at guardian.co.uk.