The new controversy also goes back to the IPCC's 2007 report in which a separate section warned that the world had "suffered rapidly rising costs due to extreme weather-related events since the 1970s".
It suggested a part of this increase was due to global warming and cited the unpublished report, saying: "One study has found that while the dominant signal remains that of the significant increases in the values of exposure at risk, once losses are normalised for exposure, there still remains an underlying rising trend."
The Sunday Times has since found that the scientific paper on which the IPCC based its claim had not been peer reviewed, nor published, at the time the climate body issued its report.
When the paper was eventually published, in 2008, it had a new caveat. It said: "We find insufficient evidence to claim a statistical relationship between global temperature increase and catastrophe losses."
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Muir-Wood's paper was originally commissioned by Roger Pielke, professor of environmental studies at Colorado University, also an expert on disaster impacts, for a workshop on disaster losses in 2006. The researchers who attended that workshop published a statement agreeing that so far there was no evidence to link global warming with any increase in the severity or frequency of disasters. Pielke has also told the IPCC that citing one section of Muir-Wood's paper in preference to the rest of his work, and all the other peer-reviewed literature, was wrong.
He said: "All the literature published before and since the IPCC report shows that rising disaster losses can be explained entirely by social change. People have looked hard for evidence that global warming plays a part but can't find it. Muir-Wood's study actually confirmed that."