Climategate just gets more interesting all the time doesn't it? The Guardian is reporting that the Climatic Research Unit (the U.K. research group at the center of the Climategate affair) has somehow lost critical temperature data again, in this case data from Chinese weather stations that are supposed to prove that the urban heat island effect accounts for a neglible portion of the warming trend found in temperature records. The abstract for the study published in 1990 in Nature reads:

Records of hemispheric average temperatures from land regions for the past 100 years provide crucial input to the debate over global warming. Despite careful use of the basic station data in some of these compilations of hemispheric temperature, there have been suggestions that a proportion of the 0.5 °C warming seen on a century timescale may be related to urbanization influences—local warming caused by the effects of urban development. We examine here an extensive set of rural-station temperature data for three regions of the world: European parts of the Soviet Union, eastern Australia and eastern China. When combined with similar analyses for the contiguous United States, the results are representative of 20% of the land area of the Northern Hemisphere and 10% of the Southern Hemisphere. The results show that the urbanization influence in two of the most widely used hemispheric data sets is, at most, an order of magnitude less than the warming seen on a century timescale.

The Guardian notes:

But many climate sceptics did not believe the claim. They were convinced that the urban effect was much bigger, even though it might not change the overall story of global warming too much. After all, two-thirds of the planet is covered by ocean, and the oceans are warming, too. But when Jones turned down requests from them to reveal details about the location of the 84 Chinese weather stations used in the study, arguing that it would be "unduly burdensome", they concluded that he was covering up the error. And when, in 2007, Jones finally released what location data he had, British amateur climate analyst and former City banker Doug Keenan accused Jones and Wang of fraud. He pointed out that the data showed that 49 of the Chinese meteorological stations had no histories of their location or other details. These mysterious stations included 40 of the 42 rural stations. Of the rest, 18 had certainly been moved during the study period, perhaps invalidating their data. Keenan told the Guardian: "The worst case was a station that moved five times over a distance of 41 kilometres"; hence, for those stations, the claim made in the paper that "there were 'few if any changes' to locations is a fabrication". He demanded that Jones retract his claims about the Chinese data.

Now Phil Jones, the head of the CRU and his Chinese-American colleague Wei-Chyung Wang, from the University of New York at Albany are admitting that the data are lost. Even more damningly, the Guardian reports:

The story has a startling postscript. In 2008, Jones prepared a paper for the Journal of Geophysical Research re-examining temperatures in eastern China. It found that, far from being negligible, the urban heat phenomenon was responsible for 40% of the warming seen in eastern China between 1951 and 2004. This does not flatly contradict Jones's 1990 paper. The timeframe for the new analysis is different. But it raises serious new questions about one of the most widely referenced papers on global warming, and about the IPCC's reliance on its conclusions.

Lest the faith in the scientific consensus be shaken further by these revelations, the Guardian article hastens to add:

It is important to keep this in perspective, however. This dramatic revision of the estimated impact of urbanisation on temperatures in China does not change the global picture of temperature trends. There is plenty of evidence of global warming, not least from oceans far from urban influences. A review of recent studies published online in December by David Parker of the Met Office concludes that, even allowing for Jones's new data, "global near-surface temperature trends have not been greatly affected by urban warming trends."

On the other hand, I reported on a recent study by University of Alabama at in Huntsville climatologist John Christy which finds that improperly accounted for heat island effects may be distorting temperature trend data:

In an email to University of Alabama climatologist John Christy I asked, "Is there a possibility that the teams that compile temperature data could all be making the same set of errors which would result in them finding similar (and perhaps) spurious trends?" Christy replied that he believed this was possible and cited some recent work he had done on temperature trends in East Africa as evidence. In that article he found that using both the maximum and minimum temperature rather than the mean temperature (TMean) used by the three official data sets gives a better indication of actual temperature trends in the region. Christy found that the maximum temperature (TMax) trend has been essentially zero since 1900 while the minimum temperature (TMin) trend has been increasing. In his email to me, Christy explained, "As it turns out, TMin warms significantly due to factors other than the greenhouse effect, so TMean, because it is affected by TMin, is a poor proxy for understanding the greenhouse effect of 'global warming'." Or as his journal article puts it, "There appears to be little change in East Africa's TMax, and if TMax is a suitable proxy for climate changes affecting the deep atmosphere, there has been little impact in the past half-century." So if Christy's analysis is correct, much of the global warming in East Africa reported by the three official data sets is exaggerated. Christy has found similar effects on temperature trend reporting for other regions of the world.

What could be increasing minimum temperatures? Christy's study suggests that the turbulence and thus temperatures in the lower levels of the atmophere are…

…highly dependent on local land use and perhaps locally produced aerosols, the significant human development of the surface may be responsible for the rising TMin while having little impact on TMax in East Africa.

In any case, Phil Jones and the CRU crowd are in the process of finding out the truth of the old adage, "It's not the crime, it's the cover up" that eventually brings someone down.

*Since the Climategate story appears to be far from over, I have decided a sequential numbering of updates will help readers keep track of developments.