At virtually the same time NASA's Goddard Institute for Space Studies was correcting historical climate data with the assistance of Climate Audit's Steve McIntyre, a British mathematician discovered serious flaws in papers used and cited by the United Nations' Intergovernmental Panel on Climate Change in its most recent Assessment Report.

Douglas J. Keenan, a former Morgan Stanley arbitrageur and current independent mathematical researcher, identified "fabrications" in such studies that suggest a "marked lack of integrity in some important work on global warming that is relied upon by the IPCC" and that "the insignificance of urbanization effects on temperature measurements has not been established as reliably as the IPCC assessment report assumes."

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Meteorological stations sometimes move, and this can affect the temperature measurements of the stations. For example, one of the stations relied upon by the above two papers was originally located on the upwind side of a city and later moved, 25 km, to be on the downwind side of the city. Such a move would be expected to increase the measured temperatures, because a city generates heat. Another station relied upon by the papers was originally located in the center of a city and then moved, 15 km, to be by the shore of a sea. Such a move would be expected to decrease the measured temperatures.

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It is clear that when a station moves, the temperature data from before the move is not, in general, directly comparable to the data from after the move. This problem can occur even if the move is over a small distance. For example, if a station moves from being in the middle of a field to being by an asphalt area, then the measured temperatures would be expected to increase, even though the distance moved might be only 100 m. (A related issue is that the land use around a station can change over time, and this can affect measurements.)

In global warming studies, an important issue concerns the integrity of temperature measurements from meteorological stations. The latest assessment report from the IPCC indicates that the global average temperature rose by roughly 0.3 °C over the period 1954-1983. Thus, if errors in temperature measurements were of similar size to, or larger than, 0.3 °C, there could be a serious problem for global warming studies. The papers of Jones et al. and Wang et al. both consider this issue. The paper of Jones et al. is one of the main 2 works cited by the IPCC to support its contention that measurement errors arising from urbanization are tiny, and therefore are not a serious problem.

With that in mind, the problem Keenan identified was that the papers in question misrepresented the static condition of a large number of weather stations:

Regarding station movements over time, the papers of Jones et al. and Wang et al. make the following statements.

The stations were selected on the basis of station history: we chose those with few, if any, changes in instrumentation, location or observation times. [Jones et al.]

They were chosen based on station histories: selected stations have relatively few, if any, changes in instrumentation, location, or observation times.... [Wang et al.]

Unfortunately, these statements appear to be quite false.
 
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