Congressional Hearings Break ‘Hockey Stick’

Published October 1, 2006

Experts testifying before a Congressional subcommittee on July 20 said a graph used by some environmentalists to illustrate “unprecedented global warming in the twentieth century” is fraudulent.

The hockey stick is an image used by the United Nations’ Intergovernmental Panel on Climate Change (IPCC) in its Third Assessment Report: Climate Change 2001. 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.

Natural Fluctuations Ignored

By 2003, however, several independent studies began to question those claims. A number of climate experts noted the Earth experienced a widely recognized Medieval Warm Period from about A.D. 800 to 1400, as well as a Little Ice Age from 1600 to 1850. The hockey stick missed both of those significant climate trends, critics noted.

Other researchers found methodological flaws with the hockey stick argument, observing some data sources were misused, several calculations were done incorrectly, and some of the data was simply obsolete.

Because the hockey stick image has been regularly used to promote and justify proposed climate change legislation, Congress asked the National Academy of Sciences (NAS) to examine the controversy.

The NAS report, released in early July, 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.

Experts Criticize Hockey Stick

In the July 20 Congressional hearings, Dr. Edward Wegman of the Center for Computational Statistics at George Mason University reported his team’s research found serious statistical flaws that undermine the main conclusion of the hockey stick study.

Wegman and his colleagues concluded that, 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.”

Wegman and his team also concluded the close ties between scientists in the small paleoclimatology community prevented true peer review of the hockey stick and related analyses.

Politicization Debated

The establishment media, both print and broadcast, were largely silent on the findings of the Congressional hearings. Several legislators seemed more interested in the political rather than the scientific ramifications of the research.

Rep. Jan Schakowsky (D-IL) stated at the hearing, “I’m very concerned that this is being used in a way to discredit the whole notion that our country and the rest of the industrialized and developing world ought to do anything about global warming. … Can you see in any way how this is being used and does it bother you?”

Wegman responded, “I can understand that it’s your job to sort out the political ramifications of what I have said. In some sense it’s not fair for you to say ‘well, gee, you reported on some fact and that’s going to be used in a bad way.'”

Dr. Hans von Storch, one of the researchers who had earlier raised questions concerning the hockey stick, agreed with Wegman, stating, “I was a bit disappointed about the comment from the lady from Illinois who said, ‘aren’t you afraid if you say this, that this would have negative implications on the policy process?’

“I was kind of shocked,” von Storch continued. “Should we really adapt what we say if that’s useful for the policy process? Is that what you expect from science? If we give advice, must we first think, is it useful for something? I think that is not the way we should operate.”

Dr. David Legates, Delaware state climatologist and director of the Center for Climate Research at the University of Delaware, said, “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.”

H. Sterling Burnett ([email protected]) is a senior fellow with the National Center for Policy Analysis.

For more information …

The July report of the National Academy of Sciences is available online at

Transcripts from the July 20 Congressional hearings will be available online at