Archive for the ‘public policy’ Category
Complex models of climate at odds with forecasting principles predict temperatures will rocket… or plummet
When the situation is complex and there is uncertainty about causal relationships, forecasting principle 6.6 dictates that forecasters should “Use few variables and simple relationships”. The opposite approach was used in the Intergovernmental Panel of Climate Change models, and there have been calls (1 , 2) for even more money to enable modelers to create models that are even more complex. Patrick Frank, in an article in Skeptic (2008, 14:1) titled “A climate of belief”, showed that a very simple model with CO2 as the only causal variable and using the IPCC assumptions about the direct and indirect effects of changes in atmospheric CO2 concentrations makes predictions of global average temperatures that are closer to the IPCC’s “ensemble average” of complex model forecasts than are those of any of the individual complex models. In other words, putting aside whether the forecasts are accurate or not, there is no need to have complex models in order to make those forecasts.
Frank’s simple model illustrates part of the purpose of principle 6.6; namely to aid understanding and reduce forecasting costs. We aren’t sure what the cost of the complex relative to the simple modeling efforts were but, given the number of people and computer time involved in the complex models, a ratio of 1 million to 1 is a conservative guess. Frank’s simple model is simple enough for anyone to understand. That’s a good thing, because the modeler’s assumption are clear and can be tested and disputed, and the disputation can be understood by others. This makes it easier to reject a false model and thereby to advance scientific understanding. Thus the use of simple models reduces mistakes, another purpose of the principle.
The primary purpose of many of the forecasting principles is naturally enough to improve accuracy; principle 6.6 is no exception. Frank demonstrates that the IPCC grossly under-reports the cumulative uncertainty of the model forecasts. The figure below from Frank’s article shows that, when proper allowance is made for uncertainty about the effects of clouds and greenhouse gases on global average temperatures, the complex IPCC models cannot legitimately tell us better than that the temperature change by the end of the century will be somewhere between +120-degrees-C and -120-degrees-C. It would be foolish indeed to base public policy on forecasts from such models.
Patrick Frank’s article is available from the Skeptic site.
Read this article and more at PublicPolicyForecasting.com.
Secretary of the Interior ignores scientific evidence on forecasting, instead favoring experts’ opinions to list thriving polar bear population as threatened
Secretary of the Interior Dirk Kempthorne announced on May 14, 2008 that he is accepting the recommendation of U.S. Fish and Wildlife Service Director Dale Hall to list the polar bear as a threatened species under the Endangered Species Act (ESA). The listing is based on the best available science, which shows that loss of sea ice threatens and will likely continue to threaten polar bear habitat. This loss of habitat puts polar bears at risk of becoming endangered in the foreseeable futures”. See the U.S. Department of the Interior website for the full announcement.
This extraordinary announcement is at odds with evidence that the polar bear population is currently thriving, and is based on false assumptions and unscientific forecasting procedures. The forthcoming Interfaces paper by Armstrong, Green, and Soon, provides evidence that the “best available science” does not support a listing.
Polar bear fears groundless
The U. S. government commissioned studies to support the listing of polar bears as a threatened or endangered species. Polar bear numbers are currently high and the population has been increasing rapidly in recent decades. Everyone likes polar bears, so this is good news. A decision to list would require forecasts that the current upward population trend will reverse. The government studies concluded that polar bear populations would decrease substantially.
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. Three scientists, J. Scott Armstrong of the University of Pennsylvania, Kesten Green of Monash University, and Willie Soon of The Harvard-Smithsonian Center for Astrophysics, audited the government studies to assess whether they were consistent with forecasting principles. Their paper, “Polar Bear Population Forecasts: A Public-Policy Forecasting Audit,” 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.
They concluded that the government forecasts were based on false assumptions and their polar bear population forecasts contravened many principles for scientific forecasting. Indeed, the reports followed fewer than one-sixth of the relevant principles. Given the importance of the forecasts, all principles should be properly applied. In short, the government reports do not provide relevant information for this decision.
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. Because the polar bear population has been increasing over recent decades, however, a continuation of that trend over the short term is possible.
Copies of Armstrong, Green and Soon’s forthcoming paper are available at http://publicpolicyforecasting.com.
Q&A With Senator Boxer
Below are excerpts from the Q&A session between Armstrong and Senator Boxer. Full Text of Examining Threats and Protections For the Polar Bear.
Senator Boxer. Now, Dr. Scott, you are a Ph.D. in what? Dr. Armstrong.
Mr. Armstrong. I went to MIT, so I basically had three areas, one was economics, the other was social psychology and the other was marketing.
Senator Boxer. Economics, social psychology and marketing. Are you a biologist?
Mr. Armstrong. No.
Q&A With Senator Inhofe
Below are excerpts from the Q&A session between Armstrong and Senator Inhofe. Full Text of Examining Threats and Protections For the Polar Bear.
Dr. Armstrong, when you were talking, this chart up here, first of all, did you say that you had a paper that you wrote in 1978?
Mr. Armstrong. I was writing books on long range forecasting then.
Senator Inhofe. You were writing books in 1978?
Mr. Armstrong. Well, I have been in this field for 48 years now.
Senator Inhofe. Wow. I thought maybe I heard wrong. You are the forecasting expert, I recognize that.
Armstrong presents testimony at the US Senate Committee on Environment and Public Works
On January 30, 2008, Scott Armstrong gave a talk presenting his findings to the US Senate Committee on Environment and Public Works’ “Examining Threats and Protections for the Polar Bear”. Click here for full text of the talk. The following are selected excerpts. Full text is available of the paper “Polar Bear Population Forecasts: A Public Policy Forecasting Audit” by Armstrong, Green, and Soon.
We conducted forecasting audits of two of the nine administrative reports that were prepared in 2007 to “…Support U.S. Fish and Wildlife Service Polar Bear Listing Decision.” We selected the reports Amstrup et al. and Hunter et al. as they appeared to be the primary forecasting documents. Our concern was to establish whether the reports’ forecasts of the polar bear population over the balance of the 21st Century were the product of scientific procedures.
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Anchorage Daily News: Lacking studies, state still disputes polar bear ‘doom’
The following are some excerpts from the article discussing Alaska’s decision whether to list polar bears as endangered or not. Click here for the full text available online.
Ken Taylor has had easier jobs than this one. It’s not like the good old days chasing rhinos, climbing into bear dens and wrestling beluga whales in shallow water.
These days, sitting at a desk as deputy commissioner of fish and game, the veteran wildlife biologist has to muster the best science he can find to argue that Alaska’s polar bears are in good shape and need no special protection from hypothetical doomsday scenarios.
This requires Taylor to stand up to the prevailing wisdom about global warming in most of the world’s scientific community and the public — not to mention some pretty strong opinions in his own department.
But Taylor, the Palin administration’s point man on polar bears, argues that the scientific justification simply isn’t there — at least not yet — to declare the polar bear “threatened” and touch off a cascade of effects under the Endangered Species Act. A decision on the bears is expected from the U.S. Department of the Interior in the next few weeks.
“From my perspective, it’s very difficult to put a population on the list that’s healthy, based on a projection 45 years into the future,” Taylor says. “That’s really stretching scientific credibility.”
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The state also pokes at studies used to predict the future of polar ice, quoting at length from the climate scientists’ own demurrals about margins of error. The chain of predicted problems following from those studies are based on “unsupported conjecture,” the state says.
The state’s critique was based on the work of a consultant, J. Scott Armstrong, a University of Pennsylvania expert on mathematical forecasting who has elsewhere challenged former vice president Al Gore to a $10,000 bet on whether the globe is truly warming.
U.S. Senate Report: Over 400 Prominent Scientists Disputed Man-Made Global Warming Claims in 2007
Scott Armstrong and Kesten Green are two of the over 400 prominent scientists featured in a Senate Report debunking the scientific “consensus” on global warming. The report was released December 20th, 2007, and can be accessed at the U.S. Senate Committee on Environment & Public Works site. The following is a selected excerpt citing Armstrong’s climate challenge to Al Gore, scientific forecasts versus forecasts by scientists, and the recent study of polar bear prediction methodology.
Internationally known forecasting pioneer Dr. Scott Armstrong of the Wharton School at the Ivy League University of Pennsylvania and his colleague Kesten Green of Monash University in Australia challenged Gore to a $10,000 bet in June 2007 over the accuracy of climate computer models predictions. “Claims that the Earth will get warmer have no more credence than saying that it will get colder.” According to Armstrong, the author of Long-Range Forecasting, the most frequently cited book on forecasting methods, “Of 89 principles [of forecasting], the [UN] IPCC violated 72.” Armstrong and Green also critiqued the Associated Press for hyping climate fears in 2007. “Dire consequences have been predicted to arise from warming of the Earth in coming decades of the 21st century. Enormous sea level rise is one of the more dramatic forecasts. According to the AP‘s Borenstein, such sea-level forecasts were experts’ judgments on what will happen,” Armstrong and Green wrote to EPW on September 23, 2007.
Are polar bears endangered? It is all about the forecasts.
A forecasting audit conducted by Scott Armstrong, Kesten Green and Willie Soon has concluded that the government’s administrative reports do not rely on scientific forecasting procedures. Thus, it would be irresponsible to classify polar bears as an endangered species. The authors are seeking additional peer review for their paper.
Speculation Elimination: Did the Bush administration really censor science?
Paul Georgia on National Review Online concludes with a reference to the Green and Armstrong (2007) paper in his article “Speculation Elimination,” critiquing the press’s emphasis on the Bush administration’s “censoring” of science.
The claim that the Bush Administration censored science is without merit. What it seems to have done, is cut the portions of the testimony that were based in expert speculation about the future. According to the scientific literature on forecasting, expert opinion is the least reliable source for accurate predictions.
A new paper by Professors Scott Armstrong and Kesten Green, leading experts on forecasting, argues that “Comparative empirical studies have routinely concluded that judgmental forecasting by experts [rather than scientific forecasting] is the least accurate of the methods available to make forecasts.” They also show that, “Agreement among experts is weakly related to accuracy,” when it comes to forecasting.
The media storyline is backwards. Rather than censoring science, the Bush Administration responsibly removed baseless speculation from the CDC’s testimony. If the purpose of congressional hearings is “fact finding,” then such speculation is inappropriate and the Administration acted appropriately.
Paul Georgia is the executive director of the Center for Science and Public Policy. The article was adapted from a paper published by the Center.
The Global Warming Challenge 