Some readers may have heard me on Wednesday night's Moral Maze on BBC Radio Four on the subject of Kyoto (repeated on Saturday night at 2215). I was battling vainly against a green witness, my three fellow panellists and the chairman to get them to acknowledge not just that there was a division of scientific opinion about global warming but that, one by one, the key claims supporting the theory wwre being demolished. Now theWall Street Journal draws attention to the fact that one of these claims, which was absolutely crucial in informing the Kyoto protocol, has turned out to be not worth the paper it was written on. Michael Mann's 'hockey stick' curve showed continuous temperatures for about 700 years and then a sharp upward rise in the past 100 years. So persuasive was this 'hockey stick' research for the theory that global warming was happening and was caused by man-made emissions that it appeared no fewer than five times in the Intergovernmental Panel on Climate Change's landmark 2001 report on global warming. Doubts, however, were expressed from the start since Mann's research managed to air-brush out of of the historical picture altogether the medieval warm period in Europe, which lasted for about six centuries and when temperatures were some two degrees higher than they are now. Some omission!

As the Journal relates:

'Still, questions persisted. In 2003, Stephen McIntyre, a Toronto minerals consultant and amateur mathematician, and Ross McKitrick, an economist at Canada's University of Guelph, jointly published a critique of the hockey stick analysis. Their conclusion: Mr. Mann's work was riddled with "collation errors, unjustifiable truncations of extrapolation of source data, obsolete data, geographical location errors, incorrect calculations of principal components, and other quality control defects." Once these were corrected, the Medieval warm period showed up again in the data.

This should have produced a healthy scientific debate. Instead, as the Journal's Antonio Regalado reported Monday, Mr. Mann tried to shut down debate by refusing to disclose the mathematical algorithm by which he arrived at his conclusions. All the same, Mr. Mann was forced to publish a retraction of some of his initial data, and doubts about his statistical methods have since grown. Statistician Francis Zwiers of Environment Canada (a government agency) notes that Mr. Mann's method "preferentially produces hockey sticks when there are none in the data." Other reputable scientists such as Berkeley's Richard Muller and Hans von Storch of Germany's GKSS Center essentially agree.'

Now, McIntyre and McKitrick have produced an even more devastating demolition of Mann's 'hockey stick'. Writing in Geophysical Research Letters, they say:

'The “hockey stick” shaped temperature reconstruction of Mann et al. (1998, 1999) has been widely applied. However it has not been previously noted in print that, prior to their principal components (PCs) analysis on tree ring networks, they carried out an unusual data transformation which strongly affects the resulting PCs. Their method, when tested on persistent red noise, nearly always produces a hockey stick shaped first principal component (PC1) and overstates the first eigenvalue. In the controversial 15th century period, the MBH98 method effectively selects only one species (bristlecone pine) into the critical North American PC1, making it implausible to describe it as the “dominant pattern of variance”. Through Monte Carlo analysis, we show that MBH98 benchmarks for significance of the Reduction of Error (RE) statistic are substantially under-stated and, using a range of cross-validation statistics, we show that the MBH98 15th century reconstruction lacks statistical significance.'

'Their method...nearly always produces a hockey stick...'

Wow.

And so many people have made huge reputations from all this rubbish. What an astonishing scientific scandal this is, and growing by the day.