Global warming legislation would fail

The New Zealand Climate Science Coalition

3 September 2009
For Immediate Release

Global warming legislation would fail a proper regulatory impact assessment

There are no scientific forecasts to support the belief that emissions trading will benefit New Zealanders, says Wellington-based Monash University forecasting researcher, Dr Kesten Green.

“As I understand it, the espoused purpose of the legislation is to make a contribution to keeping global average temperatures from reaching levels dangerously higher than current levels during the 21st century. A proper regulatory impact analysis of the emissions trading legislation would require scientific (evidence-based) forecasts of global average temperature without the policy, forecasts of the effects of any changes in global mean temperatures, and forecasts of the costs and benefits of all of the effects of the proposed policy, and of other reasonable policies, on temperatures and on people.

In a paper to be published in the International Journal of Forecasting later this year, Dr Green and co-authors Dr Scott Armstrong, of the University of Pennsylvania, and Dr Willie Soon, of the Harvard-Smithsonian Center for Astrophysics, using evidence-based proceduresforecast that the global averagetemperature for the year 2100, and for every intervening year, will bethe same as the 2008 temperature; plus or minus 0.5 degrees Celsius. In other words, the annual global averagetemperature is unlikely to change much, in either direction,overthis century.

The authors, who are internationally known as experts in forecasting methods (Green and Armstrong) and climate (Soon), concludedthat given the complexity of climate and uncertainty over why and how climate changes, a simple forecast that average temperatures will not changewas appropriate. They further reasoned that it would be hard if notimpossible to make forecasts that were more accurate than this benchmark.

In a large-scale study involving 7550 forecasts for horizons from one to 100 years, Dr Green and his colleagues tested whether the UNIntergovernmental Panel on Climate Change’s (IPCC) projections were more accurate than the benchmark forecasts. “We projected the IPCC’sglobal warming rate of 0.03 degrees Celsiusper year successively over the period of exponential CO2growth and increasing global average temperatures from 1851 to 1975. The errors from the projections were more than seven times greater than the errors from the simple no-changeforecasts, and the difference got larger the longer the forecast horizon. Our studyillustrates the importance of finding out whether it is possible to obtain forecasts that are more useful than those from a simple benchmarkbefore making expensive policy decisions.”

Dr Green says these findings show that the IPCC projectionsare not a sound basis for public policy decisions. “Our scientific forecast that global average temperatures will not change provides the information that our political leaders need in order to make rational decisions about climate policy.”Dr Green concluded.

ENDS

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