Archive for September 2007
Bonner Cohen’s article on TCS Daily, “Gore Dodges Repeated Calls to Debate Global Warming” covers the increasing numbers of skeptics who have challenged Bush, including Armstrong. Does understanding both viewpoints change public opinion? Below is an excerpt summarizing a recent debate between skeptics and alarmists, and audience reaction:
“Gore’s reluctance to go toe-to-toe with global warming skeptics may have something to do with the – from the standpoint of climate change alarmists – unfortunate outcome of a global warming debate in New York last March. In the debate, a team of global warming skeptics composed of MIT scientist Richard Lindzen, University of London emeritus professor of biogeology Philip Stott, and physician-turned novelist/filmmaker Michael Crichton handily defeated a team of climate alarmists headed by NASA scientist Gavin Schmidt. Before the start of the nearly two-hour debate, the audience of several thousand polled 57.3 percent to 29.9 percent in favor of the proposition that global warming is a “crisis.” At the end of the debate, the numbers had changed dramatically, with 46.2 percent favoring the skeptical point of view and 42.2 percent siding with the alarmists.”
Dire consequences have been predicted to arise from the warming of the Earth in coming decades of the 21st Century. Enormous rises in sea level represent one of the more dramatic forecasts. A recent article provided sea-level forecasts based on experts’ judgments of what will happen. These judgments are in turn based on experts’ predictions of global warming. The article made no reference to scientific forecasts. As shown in Green and Armstrong (2007) experts’ forecasts have no validity in situations characterized by high complexity, high uncertainty, and poor feedback. Numerous other scientists also criticized this approach.
To date we are unaware of any forecasts of sea levels that adhere to proper (scientific) forecasting methodology and our quick search on Google Scholar came up short. If such forecasts are available, please provide citations and support as to their validity. As a first step, it would be useful to summarize studies that extrapolate long-term trends; this summary could provide a benchmark for comparison with other studies.
We will provide free access to them at publicpolicyforecasting.com and request commentary at theclimatebet.com. Media outlets should be clear when they are reporting on scientific work and when they are reporting on the opinions held by some scientists. Without scientific support for their forecasting methods, the concerns of scientists should not be used as a basis for public policy.
Kesten Green and Scott Armstrong
In the Australian Financial Review (September 8, 2007), Mark Lawson’s article, “Global warming sceptics fuel hot debate” features Dr. Green, and highlights the Green and Armstrong paper. The following is an excerpt:
Global warming sceptics fuel hot debate
(Click here for full text)
“Despite being scorned, derided and accused of links with oil companies, the climate change sceptics are still out there and, although the greenhouse lobby will never admit it, occasionally scoring major points. They may also be more numerous than the greenhouse lobby or politicians believe…
A much more serious, if not devastating, attack on greenhouse claims concerning likely future temperature increases was the recent release of a paper entitled Global Warming: Forecasts by Scientists versus Scientific Forecasts.
Written by J. Scott Armstrong, a professor of marketing at The Wharton School, University of Pennsylvania, and Kesten Green, a visiting fellow at the business and economics forecasting unit at Monash University in Melbourne, the paper assessed, as forecasts, the temperature projections made by the Intergovernmental Panel on Climate Change earlier this year. It found little to approve.”
Click for Armstrong’s PowerPoint presentation, titled “Global Warming: Forecasts by Scientists Versus Scientific Forecasts” from September 13th, 2007.
A Congressional Briefing about forecasts of global warming given by Scott Armstrong on Thursday, Sept 13 is now available on YouTube (Part 2 and Part 3). The briefing was based on the Green & Armstrong paper, “Global Warming: Scientific Forecasts or Forecasts by Scientists?” The global warming paper is the first of what they hope will be many forecasting audits of global warming studies to be presented on the new Special Interest Group page at http://publicpolicyforecasting.com.
Although climate scientists have extensive climate knowledge and are aided by computer models, their long-term forecasts are essentially their judgments of what will happen in the decades to come. Unstructured judgments are used to determine the structure and much of the content of climate models. Unstructured judgments are also used to accept or reject model outputs.
Green and Armstrong (2007) found that climate modelers do not use evidence-based principles to forecast. In fact, they violate many principles of forecasting.
One solution to this problem is to combine what is known about forecasting methods with what climate scientists know. Knowledge about forecasting is provided at http://forecastingprinciples.com. In addition, the site lists many experts in forecasting methods who are available as consultants.