NCPA - National Center for Policy Analysis


September 27, 2006

Experts testifying before a Congressional subcommittee said a graph used by some environmentalists to illustrate "unprecedented global warming in the twentieth century" is fraudulent.

The "hockey stick" depicts relatively stable temperatures from A.D. 1000 (and in later versions from 200 A.D.) to 1900, and a dramatic temperature increase from 1900 to 2000.  The conclusion drawn by the authors of the image is that human energy use over the past 100 years has caused a dramatic and unprecedented rise in temperatures across the globe.

Because the hockey stick image has been regularly used to promote and justify proposed climate change legislation, Congress asked the National Academy of Sciences to examine the controversy.  The NAS report confirmed criticisms leveled against the hockey stick:

  • Whereas the authors of the research that produced the hockey stick concluded "the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium," the NAS found little confidence could be placed in those claims.
  • In addition, the NAS found the original researchers used proxy data for past temperature reconstructions that were unreliable; that the historic climate reconstruction failed important tests for verifiability; and that the methods used underestimated the amount of uncertainty in the conclusions it reached.

The main conclusion of the hockey stick study:

  • Based on the evidence cited and methodology used by the hockey stick researchers, the idea that the planet is experiencing unprecedented global warming "cannot be supported."
  • The close ties between scientists in the small paleoclimatology community prevented true peer review of the hockey stick and related analyses.

"The 'hockey stick' picture of dramatic temperature rise in the past 100 years following 1,700 years of relatively constant temperature has now been proven false," says David Legates, Delaware state climatologist.

Source: H. Sterling Burnett, "Congressional Hearings Break 'Hockey Stick,'" Heartland Institute, October 1, 2006.


Browse more articles on Environment Issues