Climate Change (Emissions Trading and Renewable Preference) Bill
Dr Kesten Green
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 forecastingprinciples.com.
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