When the Stern Review into the Economics of Climate Change came out last year, it was showered with praise.Matthew comments:
UK Prime Minister Tony Blair called it, "the most important report on the future ever published by this government".
But expert critics of the review now claim that it overestimates the risk of severe global warming, and underestimates the cost of acting to stop it.
Richard Tol is a professor at both Hamburg and Carnegie Mellon Universities, and is one of the world's leading environmental economists.
The Stern Review cites his work 63 times; but that does not mean he agrees with it.
"If a student of mine were to hand in this report as a Masters thesis, perhaps if I were in a good mood I would give him a 'D' for diligence; but more likely I would give him an 'F' for fail.
"There is a whole range of very basic economics mistakes that somebody who claims to be a Professor of Economics simply should not make," he told The Investigation on BBC Radio 4.
There is a brilliant bit rebutting Chris Huhne, Liberal Democrat environment spokesman, who says we can see global warming in Britain in the Thames Barrier being raised so much more in the last five years than in the five years previous. The reporter actually goes to the Thames Barrier and finds that the truth is the opposite. However, truth has been made hostage to politics. Chris Huhne's over-confident ignorance encapsulates what makes much of the global warming debate so unimpressive.