vs.

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.


  1. Paul Mars

    Does making more accurate one- to ten-year-ahead forecasts of annual mean temperatures, measured by the average absolute forecast error, compared to a naive model, prove that there are no scientific forecasts that the earth will become warmer?

  2. Steve in Princeton

    Terrific bet… Al, if you’re reading, I will side wager $500 with you and give a 2-to-1 payout if Dr. Armstrong is wrong. Hello…?

  3. George Winski

    Can the average Joe get into this bet? I’d second ‘Steve in Princeton’s’ side wager of $500 with 2 to 1 payout if Dr. Armstrong is wrong — seems like such a great sucker bet!

  4. tm

    Here’s a link to a journal article that presents highlights of a study that uses one natural process (Earth Magnetic Field Variation) variable that can predict global temperatures 6 to 7 years in the future… And there’s no one other variable that can do that.

    http://www.gsaaj.org/articles/TempPaperv1n22007.pdf

    Edward Moran

  5. Charles G. Battig, MD

    Sounds like fun, but….

    This is a focus on temperature alone. It sounds as though only surface temperature is being measured. Getting agreement as to the sampling sites should in itself be entertaining. Let’s avoid urban/industrial areas, deforrested areas, new agricultural digs etc. Let’s include the polar cap areas, Siberia, mountain tops, deserts etc.

    What about also measuring upper atmospheric temperatures at the same time? The upper atmospheric temperatures have risen less than those at the earth’s surface; a worrysome flaw in the greenhouse theory.

    No matter the outcome of this contest, nothing will emerge to address causation. I “bet” that average global temperature will increase as expected from the cyclic natural events so well doumented by Prof. S. Fred Singer.

  6. moodr

    Rising temperatures at the moment is more important than what have caused them, I think. Global warming is so obvious especially in tha last 20 years.

  7. weethan

    Why are we debating about this when it actually has no relevance to the Global Warming issue?

    We should stop arguing about if the records or forcasts are accurate, or if Global Warming is actually ‘real’ and focus on sustainable energy sources and way to decrease the harmful effects of emissions and pollution on the environment. Even if the world doesn’t warm due to Global Warming, if we actually do something about the other issues that surround it, we would be doing something productive for the Earth and future generations. Better to be safe than sorry.

    If Al Gore actually took on this challenge (which would be rather one sided, because he is not qualified for this sort of work) and lost, wouldn’t that just mask all the global awareness about the Earth he has put forward and how we are damaging the environment?

    This challenge is tossing away the real issue here.

  8. Rcherry

    Professor Armstrong’s sound bite is only an attempt of bait and switch, taking the eye off the ball, a childish prank. The requirement of the human species to take care of the earth can not be altered by a half wit scholar with an alternative agenda. The assertion that the earth is not sick proves his ploy. To visit any conservation area you may have visited when you were a child proves this. Fix the earth now!

  9. kinger

    fix the earth now?? Rcheery really, the earth is not an engine, what should we replace the spark plug?
    Why do people think we can save the earth or change the climate change? Try saving your city or fellow man then get back with me. Oh wait, that would be an inconvience.

  10. JChandler

    weethan, I am at a loss to understand your point. Are you saying “let’s not debate whether global warming is a) happening or b) predictable or c) caused by largely or primarily by humans, let’s just act as if it is?”

    If so, I think you must have a real misunderstanding of the costs of reducing greenhouse gas emissions. If it were easy or costless to do that, then I would agree with you. But it’s not.

  11. chris mclaughlin

    Weethan and Rcherry, So are you now conceeding that you’ve lost the “tax us because of global warming” scare argument and now your new ploy is “tax us to save the earth” guilt argument? Talk about bait and switch. Sorry, but we’re not buying this argument either. When your suggestions become tenable the invisible hand of the market place will adopt them. Don’t take yourselves so seriously. You’ll overheat and contribute to global warming. Now let’s all just chill out, take it easy, and I won’t force you to buy a handgun if you won’t ram your socialist stealth taxes ideas down my throat. That’s not to say you aren’t free to sell all your belongings and contribute their proceeds to developing alternative energy sources. Go for it. Put your money where your mouth is. We won’t stop you.

    Chris McLaughlin
    Orange Park, FL

  12. chris mclaughlin

    Ooops, give me back one of those “e”s in conceding, please. I might need it, later.

  13. moptop

    “Rising temperatures at the moment is more important than what have caused them”

    If you don’t know what is causing them, spending trillions on a solution is ill advised, to say the least. But then again, I am not part of the “reality based” left, so what do I know?

  14. Dan

    Al Gore’s global warming hysteria is making him big bucks every time he sells foolish people carbon offsets. Fools like you that think human activity is responsible for climate change rather than solar activity are so arrogant. You think everything in the universe can be controlled and manipulated by the human race! The only thing being manipulated is the population of fools buying into the climate change hysteria. You think computer models that don’t take into account atmospheric and oceanic effects (because they are not understood well enough to model) are somehow worth changing your lifestyles? Go ahead! Al Gore and gaia will thank you!

  15. Elim

    Why not 1000 Points? why only 10? we can get data for 40 years on more that 1000, and the warming is a global total not just a few points? I mean some places are bound to get colder from the jetstrem shifting, so 10 is a damn small test set. So why not 1000, 10,000?

    I smell a rat.

  1. 1 I’ll See Your Climate Models… and Raise You $10,000 at f.t.h.

    […] professor of forecasting methods at the Wharton School, an internationally ranked business school, challenged Al Gore to a $10,000 bet on the viability of current climate […]

  2. 2 James' Empty Blog

    More on the “$20,000″ bet

    Following on from this post, I emailed J Scott Armstrong, he pointed me to this web site/blog and the bet is outlined in more detail in this post.

    At a glance, he is using the most obvious and trivial trick



Leave a Comment