Forecast for Polar Bears Is Bright

Published April 3, 2008

(Chicago, IL – April 3, 2008) — Who doesn’t like polar bears? They’re cute and cuddly, and lend themselves to heart-melting images.

So when the federal government commissioned studies last year to support the listing of polar bears as a threatened or endangered species, the project was greeted with near-universal acclaim.

Those studies concluded that the current growth trend in the polar bear population will reverse, and that the bears’ population will decrease substantially in the future.

But when two prominent experts on forecasting joined one of the world’s leading experts on climate change to audit the government’s forecasts, they found the forecast was based on false assumptions and violated many principles of scientific forecasting.

“Indeed,” said one of the scientists, J. Scott Armstrong of the University of Pennsylvania, “the government forecasters followed fewer than one-sixth of the relevant principles of scientific forecasting. The bottom line is that the government studies are irrelevant to the question whether polar bears are endangered or threatened.”

The audit–by Armstrong, Kesten Green of Monash University, and Willie Soon of the Harvard-Smithsonian Center for Astrophysics–has been accepted for publication in the management science journal Interfaces. It is the only peer-reviewed paper on polar bear population forecasting that has been accepted for publication in an academic journal.

“Decision makers and the public should expect people who make forecasts to be familiar with the scientific principles of forecasting, just as a patient expects his physician to be familiar with the procedures dictated by medical science,” said Armstrong.

Armstrong said research shows that for issues such as the population of polar bears–situations that are complex and where there is much uncertainty–the best forecast is that things will follow a “random walk.” In effect, this model states that the most recent value is the best forecast for all periods in the future.

Armstrong concluded, “Because the polar bear population has been increasing over recent decades, however, a continuation of that trend over the short term is possible.”

Armstrong, Green, and Soon’s forthcoming paper, “Polar Bear Population Forecasts: A Public-Policy Forecasting Audit, is available at

For more information, contact Prof. Scott Armstrong at 610/622-6480, or [email protected].

Armstrong, Green, and Soon were speakers at the 2008 International Conference on Climate Change, which attracted more than 500 scientists, economists, and policy analysts to New York City March 2-4, 2008. For more information and audio from the conference, visit