The Global Warming Challenge
The following terms were sent to Al Gore Tuesday, June 19th, 2007.
Al Gore has claimed that there are scientific forecasts that the earth will become warmer and that this will occur rapidly. University of Pennsylvania Professor J. Scott Armstrong, author of Principle of Forecasting: A Handbook for Researchers and Practitioners, and Kesten C. Green, of Monash University (and Armstrong’s Co-Director of forecastingprinciples.com), have been unable to locate a scientific forecast to support that viewpoint. As a result, Scott Armstrong offers a challenge to Al Gore that he will be able to make more accurate forecasts of annual mean temperatures than those that can be produced by current climate models.
The general objective of the challenge is to promote the proper use of science in formulating public policy. This involves such things as full disclosure of forecasting methods and data, and the proper testing of alternative methods. A specific objective is to develop useful methods to forecast global temperatures. Hopefully other competitors would join to show the value of their forecasting methods. These are objectives that we share and they can be achieved no matter who wins the challenge.
Al Gore is invited to select any currently available fully disclosed climate model to produce the forecasts (without human adjustments to the model’s forecasts). Scott Armstrong’s forecasts will be based on the naive (no-change) model; that is, for each of the ten years of the challenge, he will use the most recent year’s average temperature at each station as the forecast for each of the years in the future. The naïve model is a commonly used benchmark in assessing forecasting methods and it is a strong competitor when uncertainty is high or when improper forecasting methods have been used.
Specifically, the challenge will involve making forecasts for ten weather stations that are reliable and geographically dispersed. An independent panel composed of experts agreeable to both parties will designate the weather stations. Data from these sites will be listed on a public web site along with daily temperature readings and, when available, error scores for each contestant.
Starting at the beginning of 2008, one-year ahead forecasts then two-year ahead forecasts, and so on up to ten-year-ahead forecasts of annual “mean temperature” will be made annually for each weather station for each of the next ten years. Forecasts must be submitted by the end of the first working day in January. Each calendar year would end on December 31.
The criteria for accuracy would be the average absolute forecast error at each weather station. Averages across stations would be made for each forecast horizon (e.g., for a six-year ahead forecast). Finally, simple unweighted averages will be made of the forecast errors across all forecast horizons. For example, the average across the two-year ahead forecast errors would receive the same weight as that across the nine-year-ahead forecast errors. This unweighted average would be used as the criterion for determining the winner.
Terms of the challenge can be modified by mutual agreement.
If Al Gore accepts the challenge, each party would invest $10,000 in a mutually agreed Charitable Trust stock account on December 1, 2007. The charity will receive the total value in the fund when the official award is made at the annual International Symposium on Forecasting in 2018. Should Scott Armstrong win, the gift would be made to the Institute for Justice, in Arlington, Virginia. Should Al Gore win, he will designate the charity.
Details on the challenge and related materials such as the paper on climate forecasting by Armstrong and Green are provided at publicpolicyforecasting.com. To facilitate open discussion, a blog is provided at theclimatebet.com.