PANEL STUDY FAILS TO SETTLE DEBATE ON PAST CLIMATES
The Wall Street Journal, 23 June 2006
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By ANTONIO REGALADO
An expert panel called on to resolve a politically charged scientific debate said that the key conclusion of a widely cited study of past temperatures is "plausible" but not proved.
The report by the 12-member committee of the National Research Council was prepared after a political fight broke out over the "hockey stick," a reconstruction of past temperatures from tree rings, buried ice and other records.
Far from resolving the debate, the panel's findings yesterday drew widely different reactions among climate experts and on Capitol Hill, where the hockey-stick graphic has long been a lightning rod in the debate over global warming.
The graphic, created in 1998 by climatologist Michael E. Mann and colleagues, gets its name from the rapid, blade-like rise of recent temperatures compared with past centuries. The hockey stick became a prominent scientific symbol after it appeared in an influential 2001 United Nations report. Citing the work of Dr. Mann and others, the U.N. concluded there was a 60% to 90% chance that temperatures in the 1990s had been the warmest since 1000, and that 1998 was the warmest single year.
Panel chairman Gerald R. North, a climatologist at Texas A&M University, said his committee's findings couldn't support that claim. Dr. North said the limited data available on ancient climate means that scientists can say with high confidence only that the "last few decades" of the 20th century were the warmest period in the past 400 years, and with "less confidence" that they were the warmest in the past 900 years.
Skeptics of global warming yesterday embraced the panel's findings. Sen. James Inhofe, an Oklahoma Republican who has called global warming a "hoax" and is opposed to limits on greenhouse gases, said in a written statement that the report proved "the hockey stick is broken."
However, the study also noted that there was very little evidence to suggest that Dr. Mann's claim wasn't correct, leading others to take an opposite view. Roger Pielke Jr., head of the University of Colorado's Center for Science and Technology Policy Research, called the study a "near-complete vindication" of Dr. Mann's work and reputation.
Thermometer measurements have shown a more than one-degree rise in temperature over the past century, and the rise has been linked by other research to man-made greenhouse gases, primarily the carbon dioxide produced by burning coal or gasoline.
Scientists predict the planet will warm between two and more than 10 degrees more this century, a development that many fear will prove disastrous.
Some skeptics think the danger of global warming is overstated. The hockey stick became a special focus of criticism after an amateur Canadian mathematician and petroleum consultant, Stephen McIntyre, published articles charging serious flaws in the work.
Texas Rep. Joe Barton, the Republican head of the House Energy and Commerce Committee, launched a probe of the hockey stick last July. That probe is continuing, according to the committee.
Mr. Barton's investigation drew criticism from scientific groups, as well as fellow Rep. Sherwood Boehlert (R., N.Y.), who called on the National Research Council, a private, nonpartisan advisory group, to carry out the study published yesterday.
Mr. Boehlert said the report shows scientists still have work to do understanding ancient temperatures. "Congress ought to let them go about that work without political interference," he said in a prepared statement.
Copyright 2006, WSJ