The Global Warming Challenge

Evidence-based forecasting for climate change

Gore’s Responses

with 3 comments

On Tuesday June 19th, 2007, the terms of the Global Warming Challenge were mailed, faxed, and emailed to Al Gore. The following is the communication that has occurred between Al Gore’s associates and Scott Armstrong since then.

Received Thursday, June 28, 2007:

Thank you for inviting Mr. Gore to Speak at the International Symposium on Forecasting yesterday. We are sorry that Mr. Gore was unable to attend. I hope that the event went well.

Rachel VanCleave

Sent July 5, 2007:

Dear Rachel VanCleave,

Thank you for your email of Thursday, June 28, 2007.

As indicated in my letter to Mr. Gore, I made the official announcement of my Global Warming Challenge on Wednesday, June 27th at the 27th Annual International Symposium on Forecasting.

I look forward to receiving Mr. Gore’s response. As stated, the terms of the Challenge are open to change.

The Challenge provides an opportunity for Mr. Gore to encourage the application of scientific methods to forecasting climate change. By combining scientific forecasting methods with knowledge about the climate, we can determine which policies will be in the public’s best interest. Mr. Gore’s participation would have enormous benefits in this push to identify the best policies.

Mr. Gore can find reader comments and media responses to the Global Warming Challenge at There has been and continues to be considerable interest and discussion concerning the Challenge.

I would be pleased to send Mr. Gore a copy of my Principles of Forecasting book if you would send along the proper mailing address. The book provides empirical evidence underlying the forecasting principles used.

Scott Armstrong

Received July 6, 2007:

Due to demands on Mr. Gore’s time, he will be unable to take on ANY new projects at this time. Unfortunately he will be unable to participate in the Global Warming Challenge. Mr. Gore joins me in appreciation for your efforts and I wish you the best of luck with your efforts. Thank you for understanding and Thank you for thinking of Mr. Gore.


Rachel VanCleave

Sent July 6, 2007:

Dear Rachel VanCleave,

Thank you for your email of July 6.

There must be a misunderstanding about my Global Warming Challenge. I designed it so that it would require only a few minutes of Mr. Gore’s time. He needs merely to nominate one of the many climate models that he has relied upon – or to ask someone on his staff to do so. All technical details can be worked out between his selected climate modelers and myself.

Mr. Gore continues to devote much time and energy to the problem of global warming. By spending only a few minutes (and donating $10,000 dollars to a charity), he can help to promote the use of scientific methods of forecasting, an area that is currently overlooked by climate modelers. This would add enormously to our efforts to obtain better policies in preparing for climate changes. The Global Warming Challenge fits with his goal of applying science to pubic policy.

You stated that Mr. Gore is quite busy currently. Please let me know when he would be able to spend a few minutes to take on the Global Warming Challenge.

Scott Armstrong

Received July 6, 2007:

I am regretting Mr. Gore’s participation on behalf of his communications director and his scheduler. Please understand that Mr. Gore is not taking on any new projects at this time. Thank you.

Sent July 6, 2007:

Dear Communications Director and Scheduler,

As noted previously, I understand that Mr. Gore is currently very busy.

Mr. Gore said we need to offer “genuinely meaningful solutions to the climate crisis.” The purpose of my email was to find out when he would have time. He could do enormous good for the scientific study of this problem by spending five minutes on the Global Warming Challenge, when time permits.

When might that be?

Scott Armstrong

Received July 29, 2007

Thank you for thinking of Mr.Gore and inviting him to join you on June 27th. I apologize for the late response, but Mr.Gore has an extremely busy schedule and was not able to make it. I also read that you have a book called “Principles of Forecasting”, please feel free to mail that to Mr.Gore’s office at the address listed below. Thank you for understanding and good luck with everything in the future.

Kathryn Ankner

Office of the Honorable Al Gore & Mrs. Tipper Gore
2100 West End Avenue
Suite 620
Nashville, TN 37203

Sent July 29, 2007:

Dear Kathryn Anker,

Thank you for your reply. I will mail a copy of the book to Mr. Gore that address.

As you might note from the latest posting on , Mr. Gore and I have a common interest in promoting a scientific approach to climate change.

Scott Armstrong

Sent November 28, 2007:

Honorable Albert Gore
2100 West End Avenue
Suite 620
Nashville, TN 37203

Dear Mr. Gore,

Thank you for your previous emails and your letter concerning the Global Warming Challenge. You had mentioned that you were looking forward to reading my book, Principles of Forecasting; I believe the principles are critical to making accurate forecasts for global warming.

In earlier communications, your staff mentioned that you were too busy at the time to enter in the Global Warming Challenge. As a result, I am happy to extend the deadline beyond December 1st, 2007, to March 26th, 2008. In addition, I have found a way to make your task much easier. I propose that you place $10,000 on the Hadley Centre Forecasts.

This would merely require that you sign on the “I agree” line at the bottom of this letter. Each of us would then arrange to transfer $10,000 to a trust of your choosing. The money would be invested in mutual funds, and the proceeds would go to the winner’s charity on March 26th, 2018.

As a brief reminder, here is an overview of the original Global Warming Challenge (details can be found at

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.

Details on the 10-year bet would be handled with discussions between me the Hadley Centre. I would ask an independent board to aid in this process of finding an appropriate design and to monitor the progress of the bet. You would be kept up to date, and you would have the right to ask the board to consider changing aspects of the design.

In The Assault on Reason, you stated your interest in the use of science in addressing global warming:

“We must, for example, stop tolerating the rejection and distortion of science. We must insist on an end to the cynical use of pseudostudies known to be false for the purpose of intentionally clouding the public’s ability to discern the truth. Americans in both parties should insist on the reestablishment of respect for the rule of reason. The climate crisis, in particular, could cause us to reject and transcend ideologically based distortions of the best available scientific evidence.” p. 10

I believe we have a common goal. Although I expect to win, the purpose of the challenge is to promote interest in a scientific approach to forecasting. Climate experts have done much useful work to explain the past, but their approach to forecasting does not adhere to scientific principles.


J. Scott Armstrong

For the signature of Mr. Gore:

I agree to the terms of the Global Warming Challenge with the variations specified in this letter

Sent February 14, 2008

Mr. Gore’s spokesperson replied on Armstrong’s answering phone on around February 5. The caller apologized for being so late for responding to the November 28 letter. She said, “Senator Gore declines.” No reason was given. She said to call if there were any questions. Attempts to reach her by phone failed despite leaving callback messages. Armstrong then contacted her by email with questions for Mr. Gore:

“You have made dramatic forecasts of a dire future and have asked people to make big sacrifices on the basis of those forecasts. I would be grateful if you would explain:

1. Why are you unwilling to back your forecasts in a challenge intended to promote scientific forecasting of climate change?

2. Under what conditions would you be willing to back your forecasts in a challenge against my forecasts from a simple scientific method that is appropriate in situations of high uncertainty: the naïve “no change” method?”

The spokesperson said that with respect to question #1, “Mr. Gore simply does not wish to participate in a financial wager.” Armstrong responded that it was fine by him and that we could “merely do it for its scientific value.” The spokesperson said that she would ask Mr. Gore. Armstrong asked if Mr. Gore would also respond to question #2.

Sent March 28, 2008:

March 28, 2008
Honorable Albert Gore
2100 West End Avenue,
Suite 620
Nashville, TN 37203
Fax: 615-327-2227

Dear Mr. Gore,

The extended deadline for the Global Warming Challenge has passed and, despite the fact that I have responded to all of your concerns to date regarding the challenge, you have not been willing to engage in a scientific test of your forecasts of dangerous global warming.

Despite our literature searches and our appeals both on the Internet and in our published paper on climate change, my colleague and I have been unable to find a single scientific forecast to support global warming. If you are aware of such a study, I appeal to you directly to reveal it to the scientific community so that it can be subject to peer review and so the public can see the scientific basis for your claims.

In addition we need to continue scientific studies. Thus, I pose this question:

“When and under what conditions would you be willing to engage in a scientific test of your global warming forecasts?”

I look forward to your responses. By your own words, the global warming issue remains an important one for the future of the world. Given the enormous expenditures on this issue, I hope that as a concerned and influential citizen, you will take an active role in encouraging the application of science to this issue.


J. Scott Armstrong

Written by climatebet

October 26, 2007 at 9:53 pm

3 Responses

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  1. With the concern of Global warming I am concerned for the future of my children and generations yet to come. Scientist i am sure are looking for ways to stop the progress of the deterioration of the Ozone and polar caps by slowing down the rising temp of the Earth . My husband has a sollution though it may seem simple there is some sense to it. From what I understand from Al Gore’s lecture the depletion of polar caps is exposing the oceans to the suns rays thus absorbing the heat and melting the ice . The megar amount of ice is not enough to reflect the rays back to space. Why not mass manufacture bio degradable white ping pong balls and set them to float in the areas where the iceburgs once floated to reflect the suns rays .
    As the rays bounce off the ping pong balls the water temp will cool and begin to form new ice . The balls will degrade not causing pollution , sink to the bottom of the ocean . Until the ice is a safe desired thickness we could keep making these balls and releasing them to the problem zones . Along with a polution free lifestyle that we all need to live and the possible solution we could maybe shit the earth back to a safer place. Sometimes the most simples soultions are the most effective . Thank you for your time

    Heidi Slessman

    May 15, 2008 at 12:54 pm

  2. please excuse the typo on my last message . sentance should read Along with a polltion free lifestyle that we all need to ive and the possible solution , we could maybe shift the earth back to a safer place .Thank you again . H. Slessman

    Heidi Slessman

    May 15, 2008 at 1:44 pm

  3. […] Al Gore declines to participate in a Global Warming Challenge. […]

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