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Submission to the Select Committee of the New Zealand Parliament on the Climate Change (Emissions Trading and Renewable Preference) Bill



Forecasts of global warming are not scientific and should not be used for policy making.
Climate Change (Emissions Trading and Renewable Preference) Bill
Submission by
Dr Kesten Green
Forecasting Researcher
Wednesday, February 27, 2008
Forecasts of global warming are not scientific and should not be used for policy making
I am a forecasting researcher who has published a peer-reviewed journal article describing my audit of
the methods used by the Intergovernmental Panel on Climate Change (IPCC) to make forecasts about
global temperatures over the 21st Century (Green and Armstrong 2007). I do not claim to be an expert
on climate, but I do claim that forecasts of dangerous manmade global warming are not scientific. In
the absence of scientific forecasts, there is no more reason to believe that global average temperatures
will increase over the 21st Century than there is to believe that they will decrease. It would therefore be
irresponsible to take forecasts of global warming into consideration when formulating public policy.
My co-author, University of Pennsylvania Professor J. Scott Armstrong, and I independently assessed
the procedures that were used by the IPCC to predict global warming against scientific (evidence-
based) forecasting principles.
The forecasting principles are the summarisation of more than half-a-century of scientific research on
forecasting in many fields. The work of summarizing the research was done by 39 authors and 123
reviewers for Professor Armstrong’s 2001 book Principles of Forecasting. The principles are also
available on the internet at
The IPCC authors’ seemed to be unaware of forecasting principles. The IPCC’s Fourth Assessment
Report provided sufficient information for us to make judgments on whether their procedures followed
forecasting principles for just 89 out of 140 principles. Of the 89, the IPCC procedures violated 72
principles or 81%. Some individual principles that were violated are so important that violation of any
one of them alone invalidates the IPCC’s forecasts. With the cost of taking action on the basis of
invalid forecasts so high in this situation, there is no good reason why efforts to forecast climate should
not follow all relevant principles.
I oppose the Bill’s imposition of unjustified costs on the people of New Zealand and wish to appear
before the select committee to give evidence that the Bill is based on invalid climate forecasts.
Dr Kesten C Green, Ph.D.
12 Duthie Street
Karori, Wellington 6012
Telephone +64 4 976 3245
Armstrong, J. S. (2001). Principles of Forecasting: A Handbook for Researchers and Practitioners.
Kluwer Academic Publishers.
Green, K. C. and Armstrong, J. S. (2007), Global warming: forecasts by scientists versus scientific
forecasts. Energy and Environment, 18, 997-1021. Available in full text from
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
In 2007, the Intergovernmental Panel on Climate Change's Working Group One, a panel of experts established by the World Meteorological Organization and the United Nations Environment Programme, issued its Fourth Assessment Report. The Report included predictions of dramatic increases in average world temperatures over the next 92 years and serious harm resulting from the predicted temperature increases. Using forecasting principles as our guide we asked: Are these forecasts a good basis for developing public policy? Our answer is “no”. To provide forecasts of climate change that are useful for policy-making, one would need to forecast (1) global temperature, (2) the effects of any temperature changes, and (3) the effects of feasible alternative policies. Proper forecasts of all three are necessary for rational policy making. The IPCC WG1 Report was regarded as providing the most credible long-term forecasts of global average temperatures by 31 of the 51 scientists and others involved in forecasting climate change who responded to our survey. We found no references in the 1056-page Report to the primary sources of information on forecasting methods despite the fact these are conveniently available in books, articles, and websites. We audited the forecasting processes described in Chapter 8 of the IPCC's WG1 Report to assess the extent to which they complied with forecasting principles. We found enough information to make judgments on 89 out of a total of 140 forecasting principles. The forecasting procedures that were described violated 72 principles. Many of the violations were, by themselves, critical. The forecasts in the Report were not the outcome of scientific procedures. In effect, they were the opinions of scientists transformed by mathematics and obscured by complex writing. Research on forecasting has shown that experts' predictions are not useful in situations involving uncertainly and complexity. We have been unable to identify any scientific forecasts of global warming. Claims that the Earth will get warmer have no more credence than saying that it will get colder.
Principles of Forecasting: A Handbook for Researchers and Practitioners summarizes knowledge from experts and from empirical studies. It provides guidelines that can be applied in fields such as economics, sociology, and psychology. It applies to problems such as those in finance (How much is this company worth?), marketing (Will a new product be successful?), personnel (How can we identify the best job candidates?), and production (What level of inventories should be kept?). The book is edited by Professor J. Scott Armstrong of the Wharton School, University of Pennsylvania. Contributions were written by 40 leading experts in forecasting, and the 30 chapters cover all types of forecasting methods. There are judgmental methods such as Delphi, role-playing, and intentions studies. Quantitative methods include econometric methods, expert systems, and extrapolation. Some methods, such as conjoint analysis, analogies, and rule-based forecasting, integrate quantitative and judgmental procedures. In each area, the authors identify what is known in the form of `if-then principles', and they summarize evidence on these principles. The project, developed over a four-year period, represents the first book to summarize all that is known about forecasting and to present it so that it can be used by researchers and practitioners. To ensure that the principles are correct, the authors reviewed one another's papers. In addition, external reviews were provided by more than 120 experts, some of whom reviewed many of the papers. The book includes the first comprehensive forecasting dictionary.