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.

Examining eight methods to reduce or stop global warming, Lomborg and his fellow economists recommend pouring money into researching and developing clean energy sources such as wind, wave, solar and nuclear power, and more work on climate engineering ideas such as "cloud whitening" to reflect the sun's heat back into the outer atmosphere.

In a Guardian interview, he said he would finance investment through a tax on carbon emissions that would also raise $50bn to mitigate the effect of climate change, for example by building better sea defences, and $100bn for global healthcare.

His declaration about the importance of action on climate change comes at a crucial point in the debate, with international efforts to agree a global deal on emissions stalled amid a resurgence in scepticism caused by rows over the reliability of the scientific evidence for global warming.

The fallout from those rows continued yesterday when Rajendra Pachauri, head of the UN Intergovernmental Panel on Climate Change, came under new pressure to step down after an independent review of the panel's work called for tighter term limits for its senior executives and greater transparency in its workings. The IPCC has come under fire in recent months following revelations of inaccuracies in the last assessment of global warming, provided to governments in 2007 – for which it won the Nobel peace prize with former the US vice-president Al Gore. The mistakes, including a claim that the Himalayan glaciers could melt by 2035, prompted a review of the IPCC's processes and procedures by the InterAcademy Council (IAC), an organisation of world science bodies.

The IAC said the IPCC needed to be as transparent as possible in how it worked, how it selected people to participate in assessments and its choice of scientific information to assess.

Although Pachauri once compared Lomborg to Hitler, he has now given an unlikely endorsement to the new book, Smart Solutions to Climate Change. In a quote for the launch, Pachauri said: "This book provides not only a reservoir of information on the reality of human-induced climate change, but raises vital questions and examines viable options on what can be done."

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."