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Thursday, May 7, 2009

Steven C. Amstrup, USGS, rebutts Armstrong et al. in Interfaces, regarding polar bear research and global warming

New York Times, May 7, 2009, 8:46 am

Polar Bear Listing Defended

Amstrup with bear cubsCourtesy Steven C. Amstrup. Steven C. Amstrup, a biologist with the United States Geological Survey, poses with the cubs of a sedated polar bear.

A widely cited critique of the climate and polar bear research underpinning last year’s federal listing of polar bears as threatened with extinction has itself been critiqued. The new paper, “Rebuttal of ‘Polar Bear Population Forecasts: A Public-Policy Forecasting Audit,’ ” is available online (behind a subscription wall for now) in Interfaces, the same journal that published the original work. (The journal focuses on management science and problem solving using modeling and statistics, with recent studies on an amazing array of issues, from scheduling a Belgian soccer league to long-term planning by a Catholic diocese in Texas.)

The new polar bear paper is by a group of authors led by Steven Amstrup, the United States Geological Survey polar bear biologist who led the government analysis of the bears' prospects. I’ve sent the paper to some bear and climate experts (and to the authors of the critique) to see what they think. I’ll post updates here as they come in. I’m also checking to see if the full rebuttal can be freely posted, given that the other paper is available to everyone now. That only seems fair.

Here’s Dr. Amstrup’s note about the paper:

Attack on U.S.G.S. Polar Bear Science Rebutted:

On May 15, 2008, then-Secretary of the Interior Dirk Kempthorne classified the polar bear as a threatened species under the U. S. Endangered Species Act. U.S.G.S. reports forecasting strong declines in polar bear habitat and numbers were keys to that decision. In response, Armstrong et al. (Interfaces, 38(5):382-405, 2008) questioned the General Circulation Models (GCMs) upon which U.S.G.S. analyses relied; challenged the independence of U.S.G.S. from the policy process; and criticized the methods used by the U.S.G.S. to project the future status of polar bears. In addition to publishing their critique of the U.S.G.S. reports, Armstrong and his coauthors garnered a lot of press. Armstrong testified before Congress and made numerous public statements carried by a variety of media outlets, that served to cast doubt about the reality of global warming and its threat to polar bears. They also contracted with the State of Alaska to provide justification of the State’s opposition to the listing of polar bears as a threatened species.

In a rebuttal to be published in the July-August issue of Interfaces, U.S.G.S. personnel and co-authors justify use of GCMs for forecasting future climate and show that every major point in Armstrong et al. (2008) was wrong or misleading. We reaffirm that global warming is real and that it poses a serious threat to the future welfare of polar bears. Because there is considerable misunderstanding about global warming and the ability to forecast it, and because casting doubt about global warming was central to the arguments of Armstrong and his coauthors, we provide a tutorial on global warming and how it is incorporated into climate models. In short, we show that publication of Armstrong et al. (2008) and the other associated actions of Armstrong and his coauthors only served to distract from reasoned public policy debate about polar bears and global warming. An advance copy of our rebuttal is now available online, to Interfaces subscribers, at

Steven C. Amstrup, Ph.D.
Senior Polar Bear Scientist, U.S. Geological Survey

Link to Andrew Revkin's Dot Earth blog at the New York Times:

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