NCPA - National Center for Policy Analysis


March 14, 2008

In a 2001 report, the International Panel on Climate Change (IPCC) published a graph that showed relatively stable temperatures from A.D. 1000 to 1900, with temperatures rising steeply from 1900 to 2000.  This graph, commonly known as "the hockey stick," has been used to support the theory that human energy use over the last 100 years has caused unprecedented rise global warming.  However, several studies cast doubt on the accuracy this graph, and in 2006 Congress requested an independent analysis of it, notes H. Sterling Burnett, a senior fellow with the National Center for Policy Analysis.

A panel of statisticians chaired by Edward J. Wegman, of George Mason University, found significant problems with the methods of statistical analysis used by the researchers and with the IPCC's peer review process.


  • The researchers who created the graph used the wrong time scale to establish the mean temperature to compare with recorded temperatures of the last century.
  • Because the mean temperature was low, the recent temperature rise seemed unusual and dramatic.
  • Furthermore, the community of specialists in ancient climates from which the peer reviewers were drawn was small and many of them had ties to the original authors.
  • These problems led Wegman's team to conclude that the idea that the planet is experiencing unprecedented global warming "cannot be supported."

Even using accurate temperature data, sound forecasting methods are required to predict climate change.  Over time, forecasting researchers have compiled 140 principles that can be applied to a broad range of disciplines, including science, sociology, economics and politics.

In a recent NCPA study, Kesten Green and J. Scott Armstrong used these principles to audit the climate forecasts in the IPCC's Fourth Assessment Report:

  • They found the IPCC clearly violated 60 of the 127 principles relevant in assessing the IPCC predictions.
  • It could only be clearly established that the IPCC followed 17 of the more than 127 forecasting principles critical to making sound predictions.

Source: H. Sterling Burnett, "Climate Panel on the Hot Seat," The Washington Times, March 14, 2008.


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