A Weblog monitoring coverage of environmental issues and science in the UK media. By Professor Emeritus Philip Stott. The aim is to assess whether a subject is being fairly covered by press, radio, and television. Above all, the Weblog will focus on science, but not just on poor science. It will also bring to public notice good science that is being ignored because it may be politically inconvenient.

Saturday, December 13, 2003

The Urban Heat Island effect and 'global warming'.....

One of the problems in arriving at a genuine assessment of global surface-temperature changes over the last 200 years or so remains that of the Urban Heat Island (UHI) effect, something which I personally experience every time my (often unheated) commuter train arrives at the edges of London from rural Kent. Many 'global warming' fanatics try to dismiss this issue out-of-hand, or to claim that temperature records are already fully-corrected to take into account this undeniable and well-acknowledged effect. There are other scientists, however, who believe that much of the perceived warming currently taken to indicate 'global warming' from the enhanced emission of 'greenhouse gases' is little more than a proxy for the human urbanisation of the planet.

Dr. Ian G. McKendry of The University of British Columbia has now produced a most useful 'Progress Report' on this question for the latest issue of the scientific journal, Progress in Physical Geography: 'Applied climatology' (PIPG 27(4), 2003, pp. 597 - 606). He observes that, "UHIs continue to present a problem for the detection of changes in the global surface temperature record (the so-called 'greenhouse effect'). Typically the urban bias is removed from climate records on the basis of relatively simple regression models that utilize population size as an indicator of the urban excess.... Several studies have recently exploited long historic records to illustrate that such methods may not be sufficient to adequately correct for the 'urban bias'." McKendry further points out that recent studies have also begun to examine more closely the effects of UHI intensity on meteorological conditions, a topic first considered in 1951. Some of this new work indicates that the UHI effect may well be implicated in changes in both precipitation and storm patterns.

This extremely well-referenced review is thus important for the climate-change debate. McKendry concludes: "Recent studies suggest that attemps to remove the 'urban bias' from long-term climate records (and hence identify the magnitude of the enhanced greenhouse effect) may be overly simplistic. This will likely continue to be a contentious issue in the climate change community..."

I always find it refreshing to read good, cautious science. A very nice piece, and a most elegant example of why we need more applied urban climatologists and more hard work over wild rhetoric.

Philip, in a cooler country town. Late morning coffee?

[New counter, June 19, 2006, with loss of some data]

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