The UnAustralian

Saturday, August 09, 2003
A Correction Or Two

As readers of this blog, I've written many words on the rebuttal of the IPCC emission scenarios by Ian Castles and David Henderson. Ian Castles has recently emailed me, and it seems only fair to publicly note a couple of mistakes that I've made (I've asked for permission to post the whole email, but in the mean time this will have to do).

I've stated in the past that he is a member of the Lavoisier Group. This is incorrect. The cause of the incorrect assumption comes from the Presidents Report of the Lavoiseier Group, where Peter Walsh the President stated:

"Two of our members, Bob Foster and Ian Castles, represented the Lavoisier Group at a workshop conducted by the Australian Academy for Technological Sciences and Engineering (AATSE) to review an Addendum to their 1995 Report on Climate Change on April 4 last. Although our representatives were arguing against people who have invested a great deal in global warming, it was good that they able to present in person the evidence now accumulating against the Kyoto protagonists."


"There is a new development, however, in the Kyoto debate which may be just as important as the debate about the science. One of our members, Ian Castles AO, who was formerly Australian Statistician, and who is internationally recognised for his expertise in the field of comparative statistics, took it upon himself to examine carefully the assumptions and methodology behind the IPCC's predictions of global CO2 emissions during the 21st century."

Ian Castles has stated that he (or David Henderson) isn't (nor has he been) a member of the Lavoisier Group. Rather they both know the founder, and have given permission for the Group to post their work.

Mr Castles other complaint is that I stated the he had been "slammed" by the SRES team for describing the emission scenarios as predictions rather than projections, and that the mistake actually comes from the publishers of the report. This come from an earlier post of mine which stated:

"the IPCC scenarios are projections, not predictions (he got slammed for making this mistake in his Energy & Environment paper)."

This statement referred to the SRES teams rebuttal which read:

The concept of scenarios (emphasis on plural!) owes its origins to military contingency planning and more recently various strategic planning exercises. Consequently, the objective is not to “predict” what will, but rather what could happen under a sequence of (sometimes extreme) events. Scenarios are therefore mind experiments to assess possible consequences of a series of “what if… then” developments. Appropriate evaluation criteria are internal consistency, reproducibility and plausibility of scenario “logic” rather than “likelihood” or conformity with a priori expectations of “most likely” chain of events under any particular temporal (e.g., before or after the “Asian financial crisis”) or geographical (e.g., OECD) bias. Scenarios are therefore neither predictions, nor forecasts.4 Consequently, the SRES writing team has explicitly refrained from assigning (inherently subjective)
likelihoods or “probabilities” of occurrence to the scenarios and has repeatedly cautioned against the interpretation of any scenario as “most likely” or as “business as usual” in the traditional deterministic sense of a “forecast” or “prediction” (even if these terms continue to be used in the popular media). The appropriate use of scenarios refrains from “picking” any particular chain of events, but rather focuses on how a range of scenarios describes the most important uncertainties at stake.

The footnote 4 states "This is clearly stated in SRES (2000), but unfortunately the publisher mistakenly used the word “prediction” in the short text on the back of the jacket as Mr. Castles was quick to notice (document 2(1):1 in this issue) that we as authors unfortunately caught too late to correct."

While, the term "slammed" may not be the best term, the language this blog uses is pretty informal. From my readings of the Emission Scenarios Report (as a interested amateur with no qualifications in any sort of economic modeling) I noted the difference between projections and predictions, so it seemed reasonable that Ian Castles and David Henderson (who have written on the Report in a professionally manner) should have done the same (however, one interesting twist is that I read the online version which doesn't include the publishers jacket - whereas, I presume, they read the hard-covered version). So, in a nutshell, I'm not 100% convinced that the mistaken projections vs. predictions blame can be placed entirely on the publisher, but as it is extremely peripheral to the important issue on hand (are the IPCC projections of future levels of greenhouse gases realistic), I'll concede on this point.

Mr Castles, has also sent me a copy of their rebuttal to the SRES team rebuttal, for which I'm very thankful (the Journal which it is either has been or will be published in, Energy & Environment, is the most obscure journal that I know of), as well as an article by James Schlesinger, former US Secretary of Energy. I'll blog about both of these later, when I've read them more fully (which will take some time in the case of the former, as it's quite theoretical, and my knowledge of economics is woefully inadequate).

| 5:23 PM