| Details1: | Arctic Warming in Doubt—and so are Policy Prescriptions
There has been much “Sturm und Drang” recently about a putative Arctic Warming and its multifarious impacts on the people and ecologies of the Arctic regions. Concerns have been especially intense in Canada, UK, and Northern Europe, largely because the results of an intergovernmental Arctic Climate Impact Assessment (ACIA) study have been leaked to the media. Reuters reports that some of the participants wanted to release the study just before the US elections – for maximum political impact, no doubt.
When the glossy Summary of the study was finally presented at a Washington, DC press conference on November 8 (the full scientific report will appear only in 2005), we finally learned what was behind all the stories of the past weeks about disappearing ice caps and stressed-out polar bears.
But is the Arctic really warming – as so widely advertised? How and from where did the ACIA get its strange-looking temperature data? They show a current warming trend of about 0.5C per decade, with present temperatures about 0.5C higher than the 1938 peak value. No source is indicated, making it difficult to verify the graph. [See p.23 in the 140-page ACIA Summary or click on ACIA Highlights on ]
By contrast, published results in scientific journals do not show an Arctic warming -- and are not mentioned in the ACIA Summary. An analysis based on the US Climate Data Center’s GHCN (Global Historic Climate Network) from latitude 64 degN to the Pole shows a strong warming in the early 20th century, with a peak temperature around 1938. This peak was followed by a cooling of about 1.5degC (nearly 3 degF) till about 1975 and a slow recovery; the trend since 1938 is essentially zero. An independent analysis of the Hadley Centre (UK) of temperature data from 70 to 85 degN shows similar results, with an even more pronounced peak around 1940. Ice-core data from Greenland actually show a cooling trend since 1940. [Many more references can be found on ]
Whence this disparity between the ACIA and all other published data? At the Nov. 8 press briefing, neither of the two climate scientists present could supply a source (author and/or literature reference) for the ACIA graph. Yet the whole Arctic Impact Assessment depends crucially on this alleged warming trend, claimed to be “twice the global value.”
The most likely answer to the puzzle may reside in the imaginative ACIA definition of "Arctic.” Their graph covers the region from 60 to 90 degN, whereas others use 64 degN or, more commonly, 70 degN. The ACIA thereby manages to capture an unusually strong warming trend from mid-latitude Siberia (whose cause is still disputed -- and which may even be spurious). So it seems that the result is quite sensitive to where one puts the southern boundary of the Arctic region.
It appears then that jiggling the definition of “Arctic” can generate an alarming warming trend and have a powerful effect, not only on the conclusions of the ACIA study but also on its forthcoming policy recommendations. Not really confidence-inspiring, is it?
This week, the intergovernmental Arctic Council, which sponsored the ACIA, and scientists involved in the study are meeting in Iceland -- a culmination of their 4-year effort – to develop policy recommendations. The eight governments that have been financing this exercise need to ask some hard questions about the underlying climate science – and so should the media that have been creating so much public excitement.
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Atmospheric physicist S. Fred Singer, professor emeritus at the University of Virginia and former director of the US Weather Satellite Service, participated in early US Navy expeditions to Thule (Greenland) and Resolute Bay (Canada) to establish Arctic weather stations and carry out geophysical research.
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