Bear necessities

Polarbear.jpgScientific papers are often dull, worthy screeds, difficult to read and hard to understand without considerable effort, but sometimes they are an absolute pleasure. I can heartily recommend Amstrup et al. Rebuttal of “Polar Bear Population Forecasts: A Public-Policy Forecasting Audit”, Interfaces (2009) pp. 1-17 [PDF, Woods Hole press release] as a fine example of clarity and concision — and a classic slap down of “researchers” who haven’t taken the trouble to understand what they’re writing about. The rebuttal is of a paper by Armstrong, Green and Soon (AGS) (Armstrong et al. Polar Bear Population Forecasts: A Public-Policy Forecasting Audit, Interfaces (2008) pp. 382-405 [PDF]) in the same journal last year. AGS was highly critical of two US Geological Survey papers that were instrumental in persuading the authorities to list polar bears as an endangered species. The AGS “audit” paper is extensively quoted in Ian Wishart’s Air Con, in the chapter where he explains why the bears aren’t in trouble, so by way of correction (because you won’t be getting one from him), here’s what Amstrup et al have to say…

Amstrup et al summarise the AGS criticisms thus:

The AGS audit made three major claims:

(1) AGS claimed that the GCMs that the IPCC used are not valid for forecasting future climate, and that because the USGS reports were based on outcomes of GCMs, the USGS projections of polar bear populations are invalid.

(2) AGS claimed that the USGS researchers were not objective and lacked independence from “organizational bias or pressure” during the preparation of their reports.

(3) AGS claimed the USGS researchers failed to follow certain principles of forecasting. AGS provided examples of some of these alleged failures, including, but not limited to, improper use of data, improper analysis and interpretation, and incorrect policy decisions.

Readers with long memories might recall that Armstrong and Green ran a “forecasting audit” over climate modelling in 2007, coming to the conclusion in 1) above. Unfortunately, they appear not to have noticed that they were wrong then, and are still wrong now. Amstrup et al put it this way:

In view of the compelling evidence that GCMs provide valid estimates of the climate response to GHG increases, and because policy decisions have been made based upon these estimates, the AGS claim that GCMs are not valid for forecasting the future climate is puzzling. AGS appear to have simply chosen to believe, despite the laws of physics, that human contributions of GHGs to the atmosphere do not warm the world. [my emphasis]

As academic put-downs go, that’s a corker. The whole section of Amstrup et al dealing with why climate models are useful is worth reading. On point two, Amstrup et al are equally clear:

The AGS (p. 383) claim that the USGS reports made “recommendations with respect to the polar bear listing decision” is totally unfounded (Cochran 2008). The AGS claims that the USGS reports were somehow biased reveal that the authors do not understand the difference between forecasts of ecological outcomes and policy recommendations that address the possible ranges of outcomes.

When it comes to dealing with Armstrong & Green’s “forecasting principles”, Amstrup et al are scathing:

AGS (p. 383) claimed their principles “summarize all useful knowledge about forecasting”. Anyone can claim to have a set of principles, and then criticize others for violating their principles. However, it takes more than a claim to create principles that are meaningful or useful. In concluding our rejoinder, we point out that the principles espoused by AGS are so deeply flawed that they provide no reliable basis for a rational critique or audit.

And in conclusion:

In this rejoinder, we have shown AGS to be scientifically wrong or misleading on every major point in their attempt to establish doubt about those reports.

Anyone choosing to rely on AGS as evidence that the bears aren’t in trouble has to share in Armstrong and Green’s embarrassment. Perhaps Wishart will provide an update for his readers in future editions of Air Con. But I won’t be holding my breath…


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