Wednesday, 21 March 2007

They're hot on the temperature trail

Since debunking the Mann Hockey Stick -- the centrepiece of the UN/IPCC's Third Assessment Report, which was quietly dropped from their Fourth -- scientist Ross McKitrick and statistician Steve McIntyre have both been busy.

McIntyre has been getting his teeth into the impact of the Urban Heat Island effect on the historic temperature record (see the Wikipedia discussion for an explanation of the term) , conveniently dismissed by the UN/IPCC Team on the basis of a 1990 letter to Nature by Phil Jones et al. The now famous letter is summarised (and criticised) here by Warwick Hughes.

McIntyre has been trying for some years now and without any success to get access to the figures used by Jones to check their veracity (Jones appears to keep "misplacing" the "diskette" on which these figures can be found), since in his opinion and those of many others, the many corrections needed to take account of the Urban Heat Island effect across more than a century are likely to result in more than the 0.05 degree Celsius rise allowed for by Jones in his now "seminal" letter, and now so blandly accepted by 'The Team's' Fourth Assessment Report (AR4). Says Mcintyre:
Despite the many citations, it doesn’t appear that anyone, including the IPCC, has ever tried to directly verify [Jones'] results. Does this study still stand for the proposition that UHI effects have been shown to be inconsequential? Well, the Coordinating Lead Author of this AR4 chapter was, um, Phil Jones. No one ever said that the Team needed a big locker room.
Nothing like sitting in judgement on your own seventeen-year old work, is there. (And read here for what Thrutch recommends as "a good technical post on some of the science and engineering necessary simply to collect accurate global temperature data -- data without which one can't even begin to try to understand and unravel the highly complex systems causing them": 'Turning Hot Air into Gold.')

Ross McKitrick meanwhile has been equally busy. He helped put together the Fraser Institute's Independent Summary for Policymakers [pdf] on the IPCC's Fourth Assessment Report (I've mentioned it here frequently, but if you haven't already then this is something you might like to download and print out, and keep around for a handy reference). And he's just co-authored a paper [pdf] challenging the very notion of a "global temperature." “Global temperature,” he and his co-authors conclude, is fundamentally meaningless, and models built on this concept are inherently just as meaningless. From the Abstract:
Physical, mathematical and observational grounds are employed to show that there is no physically meaningful global temperature for the Earth in the context of the issue of global warming. While it is always possible to construct statistics for any given set of local temperature data, an infinite range of such statistics is mathematically permissible if physical principles provide no explicit basis for choosing among them. Distinct and equally valid statistical rules can and do show opposite trends when applied to the results of computations from physical models and real data in the atmosphere. A given temperature field can be interpreted as both “warming” and “cooling” simultaneously, making the concept of warming in the context of the issue of global warming physically ill-posed.
David Schnare draws some conclusions therefrom.

LINKS: Jones & the Russian Urban Heat Island (UHI) - Steve McIntyre, Climate Audit
Turning hot air into gold - Power and Control
Independent Summary for Policymakers - Fraser Institute [PDF]
Does a global temperature exist? - Christopher Essex, Ross McKitrick, Bjarne Andresen [24-page PDF]
The Jones et al 1990 Letter to Nature: a rebuttal of some key points - Warwick Hughes

Is there a global temperature? - David Schare, The Hard Look

RELATED: Global Warming, Science

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