The Global Warming Challenge

Evidence-based forecasting for climate change

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Archive for the ‘kesten green’ Category

Fun Climate Forecasting Quiz

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Test your climate forecasting skills: It’s anonymous, and fun!

Go straight to the Quiz on the page here, make your forecasts for the two 25-year periods offline, then check the outcome and grade your response here.

To learn about the latest developments in climate forecasting, read the draft paper by Kesten Green, Scott Armstrong, and Willie Soon from the recent International Symposium on Forecasting in Boston (June 2012). The link to the paper is here, and supporting materials are towards the bottom of the page.

Polar bears thrive: A surprise for Boxer Committee, which preferred alarm to scientific forecasts

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In an article titled “Healthy polar bear count confounds doomsayers,” Paul Waldie in The Globe and Mail reported on 4 April…

“The number of bears along the western shore of Hudson Bay, believed to be among the most threatened bear subpopulations, stands at 1,013 and could be even higher, according to the results of an aerial survey released Wednesday by the Government of Nunavut. That’s 66 per cent higher than estimates by other researchers who forecasted the numbers would fall to as low as 610 because of warming temperatures that melt ice faster and ruin bears’ ability to hunt. The Hudson Bay region, which straddles Nunavut and Manitoba, is critical because it’s considered a bellwether for how polar bears are doing elsewhere in the Arctic.”

This report will come as no surprise to followers of, where we prefer scientific forecasting to politically motivated alarmism. For a recap on scientific forecasting’s contribution to the polar bear population question, Scott Armstrong’s letter 2008 to Senator Barbara Boxer, who chaired a hearing on the issue, is here.

The 2008 paper on polar bear population forecasting, by Scott Armstrong, Kesten Green, and Willie Soon, is available here.

To see the rest of Paul Waldie’s report on the happy state of the polar bear population in 2012, see here.

Written by admin

April 9th, 2012 at 7:26 am

Gore trails after 4 lively years of warming bet

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The Gore-Armstrong climate bet has now completed four-tenths of its ten-year race with Scott Armstrong in the lead. The latest graph and data are available to the right. Click on the graph to show a larger version of the graph with the data. You will see that we finished 2011 with average global temperatures for the year slightly lower than the bet benchmark year of 2007.

While Professor Armstrong is confident that his no-change forecasting method is better than Gore and the IPCC’s +0.03C per annum unscientific extrapolation, ten years is short in climate terms, and Mr Gore is still in with a chance. To provide some perspective, climatologists sometimes use seven years as the duration of a climate period. Over the last seven years, the UAH global temperature anomaly series has trended upwards at a rate of 0.008C per year. The solar magnetic activity cycle has a period of about 11 year. Over the last 11 years, the temperature series has had a trend of +0.019C per year. The former trend is much closer to Prof Armstrong’s no-change forecast than it is to Mr Gore’s extrapolation, but the latter is somewhat closer to Mr Gore’s extrapolation. The trend for the entire 33 year period of the UAH temperature series, at +0.0138C per annum, marginally favors Prof Armstrong’s forecasting method and suggests that there is no reason for alarm. will continue to report monthly results on The Climate Bet, assuming that Mr. Gore took the bet. Professor Armstrong maintains that changes in temperature are natural variations that occur over time. He expects the scientific approach to forecasting will win in the long-run, though he realizes the 10 years of the bet may not be long enough. When he proposed the bet, simulations of temperature changes over the previous 157 years indicated that his chances of winning would be somewhat greater than 62%.

An article by Kesten Green, Scott Armstrong, and Willie Soon in the International Journal of Forecasting explains the reasons behind Professor Armstrong’s choice of the no-change model for forecasting global average temperatures. It is available here.

Written by admin

January 10th, 2012 at 4:16 am

No change in polar bear population

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The Polar Bear Specialist Group of the International Union for the Conservation of Nature (IUCN) has reported that there was no change in the polar bear population in the most recent four-year period studied.

The finding is consistent with the conclusion of a 2008 paper by Scott Armstrong, Kesten Green, and Willie Soon (“Polar Bear Population Forecasts: A Public-Policy Forecasting Audit”) that “the inconsistent long-term trends in the polar bear population suggest that it is best to assume no trend in the long-term.”

The polar bear population finding contrasts with Senator Boxer’s hearings in January 2008 in which she expressed the view that the number of polar bears would decline rapidly. Professor Armstrong offered to bet her that the number of polar bears would not decline, but she did not respond to the challenge.

The Polar Bear group’s report can be found here.

The Armstrong, Green, and Soon paper on polar bear population forecasts can be found here.


Testimony on climate change to Congressional Science Committee

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Research on Forecasting for the Manmade Global Warming Alarm

Testimony to Committee on Science, Space and Technology Subcommittee on Energy and Environment on “Climate Change: Examining the processes used to create science and policy” – March 31, 2011

Professor J. Scott Armstrong, University of Pennsylvania,

with Kesten C. Green, University of South Australia,

and Willie Soon, Harvard-Smithsonian Center for Astrophysics


The validity of the manmade global warming alarm requires the support of scientific forecasts of (1) a substantive long-term rise in global mean temperatures in the absence of regulations, (2) serious net harmful effects due to global warming, and (3) cost-effective regulations that would produce net beneficial effects versus alternatives policies, including doing nothing.

Without scientific forecasts for all three aspects of the alarm, there is no scientific basis to enact regulations. In effect, the warming alarm is like a three-legged stool: each leg needs to be strong. Despite repeated appeals to global warming alarmists, we have been unable to find scientific forecasts for any of the three legs.

We drew upon scientific (evidence-based) forecasting principles to audit the forecasting procedures used to forecast global mean temperatures by the Intergovernmental Panel on Climate Change (IPCC)—leg “1” of the stool. This audit found that the IPCC procedures violated 81% of the 89 relevant forecasting principles.

We also audited forecasting procedures, used in two papers, that were written to support regulation regarding the protection of polar bears from global warming —leg “3” of the stool. On average, the forecasting procedures violated 85% of the 90 relevant principles.

The warming alarmists have not demonstrated the predictive validity of their procedures. Instead, their argument for predictive validity is based on their claim that nearly all scientists agree with the forecasts. This count of “votes” by scientists is not only an incorrect tally of scientific opinion, it is also, and most importantly, contrary to the scientific method.

We conducted a validation test of the IPCC forecasts that were based on the assumption that there would be no regulations. The errors for the IPCC model long-term forecasts (for 91 to 100 years in the future) were 12.6 times larger than those from an evidence-based “no change” model.

Based on our own analyses and the documented unscientific behavior of global warming alarmists, we concluded that the global warming alarm is the product of an anti-scientific political movement.

Having come to this conclusion, we turned to the “structured analogies” method to forecast the likely outcomes of the warming alarmist movement. In our ongoing study we have, to date, identified 26 similar historical alarmist movements. None of the forecasts behind the analogous alarms proved correct. Twenty-five alarms involved calls for government intervention and the government imposed regulations in 23. None of the 23 interventions was effective and harm was caused by 20 of them.

Our findings on the scientific evidence related to global warming forecasts lead to the following recommendations:

1. End government funding for climate change research.

2. End government funding for research predicated on global warming (e.g., alternative energy; CO2 reduction; habitat loss).

3. End government programs and repeal regulations predicated on global warming.

4. End government support for organizations that lobby or campaign predicated on global warming.

Full report

Global warming an excuse for government spending?

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In response to a Wall Street Journal op-ed by Bjorn Lomborg, Scott Armstrong, Kesten Green, and Willie Soon wrote the following letter questioning Lomborg’s poorly-justified advocacy.

“Let’s Deal in Science and Facts” – A letter to the Wall Street Journal

Bjorn Lomborg (“Can Anything Serious Happen in Cancun?”, op-ed, Nov. 12) claims that government spending on global warming policies is wasted, but he assumes that global warming caused by carbon dioxide is a fact. It is not. We base this statement not on the opinions of 31,000 American scientists who signed a public statement rejecting this warming hypothesis (the “Oregon Petition”), but rather because the forecasts of global warming were derived from faulty procedures.

We published a peer-reviewed paper showing that the forecasting procedures used by the U.N.’s Intergovernmental Panel on Climate Change violated 72 of 89 relevant principles (e.g., “provide full disclosure of methods”). The IPCC has been unable to explain why it violated such principles. In response, we developed a model that follows the principles. Because the climate is complex and poorly understood, our model predicts that global average temperatures will not change.

In testing the models on global temperature data since 1850, we found that the long-range (91-to-100-years ahead) forecast errors from the IPCC’s projection were 12 times larger than the errors from our simple model.

Mr. Lomborg concludes there are better ways for governments to spend the funds devoted to global warming. We suggest this money should instead be returned to taxpayers.

J. Scott Armstrong, Kesten C. Green. Willie Soon.

See the letter on the WSJ site here.

Who would win the ‘Climate Bet’, Al Gore or Scott Armstrong?

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In his talk on March 9, 2009 at the International Climate Change Conference in New York City, Wharton Professor J. Scott Armstrong will announce the launch of a prediction market on the outcome of the „Climate Bet‟ he proposed to Mr. Gore in 2007. Prediction markets are a structured scientific approach to eliciting and summarizing peoples‟ opinions. The Climate Bet prediction market is part of a project led by Andreas Graefe, a researcher at the Karlsruhe Institute of Technology (KIT) in Germany, to examine the use of prediction markets for controversial public policy issues. Are prediction markets useful in aiding the democratic process? Read the rest of this entry »

Test Your Climate Change IQ

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Take this one-question quiz and see how well you can forecast global average temperatures (Available for download here) Read the rest of this entry »

Written by mzfeldm

February 19th, 2009 at 9:48 pm

Uncertainty, the Precautionary Principle, and Climate Change

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The precautionary principle is a political principle, not a scientific one. The principle is used to urge the cessation or avoidance of a human activity in situations of uncertainty, just in case that activity might cause harm to human health or the natural environment. There is an interesting discussion of the history of the term in Wikipedia.

In practice, the precautionary principle is invoked when an interest group identifies an issue that can help it to achieve its objectives. If the interest group is successful in its efforts to raise fears about the issue, the application of the scientific method is rejected and a new orthodoxy is imposed. Government dictates follow. People who dissent from the orthodox view are vilified, ostracized, and may have their livelihoods taken away from them.

Consider the case of “climate change”. Warnings of dangerous manmade global warming from scientists, politicians, and celebrities have received much publicity. They admonish us to dramatically reduce emissions of CO2 in order to prevent disaster over the course of the 21st Century. Efforts have been made to stifle a scientific approach to the issue. In an article titled “Veteran climate scientist says ‘lock up the oil men’“, James Hanson, who heads the NASA Goddard Institute for Space Studies, was quoted as suggesting that those who promote the ideas of global warming skeptics should be “put on trial for high crimes against humanity.” The skeptics themselves have been ejected from, for example, State Climatologist positions and prevented from publishing research in mainstream journals, and they and their views are routinely attacked.

Much complexity and uncertainty surround climate change. The cumulative empirical evidence on proper forecasting procedures suggests that the most appropriate method in this case is naïve extrapolation. In simple terms, this means to forecast no change. Of course there will be change, but with current knowledge there is no more reason to expect warming than to expect cooling.

As we describe in our paper, we have been unable to find any forecast derived from evidence-based (scientific) forecasting methods that supports the contention that the world faces dangerous manmade global warming.

Appeals for urgent curtailment of human activity “just in case” are often couched in ways that imply that industrial societies are inherently sinful, rather than that there might be a problem to be dealt with. Indeed, interpretation of the precautionary principle is subjective and it is arguable that it is being misapplied to the issue of climate change.

Firstly, even if forecasts of increasing temperatures turned out to be accurate, predicted temperatures and other conditions are within the range of variations that have been experienced in the past. There is no evidence that the natural environment “prefers” relatively cool to relatively warm average temperatures. In fact, life in general prefers warmth.

Secondly, curtailing human activity would harm people’s health by making them poorer than they would otherwise have been. This is likely to be the case even if curtailing human activity happened to reduce global average temperatures. When the situation is framed in this way, the precautionary principle dictates that it is policies to curtail economically efficient human activity that should themselves be curtailed.

The outlook for the climate over the 21st Century is highly uncertain. There is a word in the English language to express high uncertainty. That word is “ignorance”. And ignorance is not a basis for responsible government action. We should expect our politicians to have the courage to resist interest groups’ calls for action in the face of ignorance.

The precautionary principle brings to mind the slogan on the Ministry of Truth building in George Orwell’s 1984: “Ignorance is Strength.” Instead of this political principle, we hope that politicians will turn to scientific principles for making public policy.

Written by mzfeldm

September 1st, 2008 at 12:15 am

Skeptics Speak Out: Dr. Kesten Green

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The Competitive Enterprise Institute presented three videos by climate and forecasting specialists. Among the three are: Dr. Joseph D’Aleo, a former meteorology professor at Lyndon State College in Vermont and the first director of meteorology at The Weather Channel; Dr. Kesten Green, of the International Graduate School of Business, Univesity of South Australia, and: Dr. Jim O’Brien, State Climatologist of Florida and director of the Center for Ocean Atmospheric Prediction Studies.

All three videos are available at GlobalWarming.Org. Kesten Green, adviser to this website, is featured below.


Kesten Green claims that the IPCC climate models incorporate just 15% of the principles and procedures appropriate to scientific forecasting. Many IPCC scientists seem to be unaware of forecasting methodology as a scientific discipline, he adds. Instead, the Monash University specialist charges that the models’ elaborate mathematical formulas reflect the IPCC staff’s own opinions at both the input and output stages.

One senior scientist and author with the IPCC ducks the charge of unscientific methodology, according to Green, by saying the UN climate models do not constitute forecasts or predictions. However, the specific words “forecast” and “prediction” reoccur many times in IPCC reports and they’re viewed that way by the public. If the IPCC in fact hasn’t made scientific forecasts, the Australian queries, what reason is there to be worried about climate change at all?

(From DOB Magazine Online)

Written by climatebet

April 29th, 2008 at 10:37 pm