Saturday, June 24, 2006

Hockey Sticks and Hot Air

Last year Rep. Sherwood Boehlert of New York asked the National Academy of Sciences to study the evidence for global warming and determine if a consensus existed. The study was meant to address controversy over the so-called "hockey stick graph" that shows a sharp increase in temperatures in the second half of the twentieth century.

Source: National Academy of Sciences via Washington Post

This week, the NAS announced its results, which affirmed the basis for the "hockey stick graph": the earth is hotter now than at any time in the past 400 years. There does seem to be some disagreement over whether the same holds true for the past 1,000 years. Here is the reasoning:

NASA scientists have concluded from direct temperature measurements that 2005 was the hottest year on record, with 1998 a close second. Because direct temperature readings only date back to 1860, however, Penn State University climatologist Michael Mann and two colleagues used "proxy" data from ice cores, coral reefs and lake sediments to estimate temperatures back 1,000 years in creating the "hockey stick" -- which gained its name from its distinctive shape.

Panel member Kurt M. Cuffey, a geography professor at the University of California at Berkeley, said at a news briefing that the report "essentially validated" the conclusions Mann reported in 1998 and 1999 using temperature records. The panel also estimated there is a roughly 67 percent chance that Mann is right in saying the past 25 years were the warmest in a 1,000 years. But it noted it is difficult to draw conclusions on temperatures before 1600 because, Cuffey said, "you start relying more and more on data from fewer geographic locations."

Unfortunately, the report does not seem likely to change minds at the upper levels of government. The anti-environment right already has its talking points ready:
But Sen. James M. Inhofe (R-Okla.), another skeptic, said the academy's report highlights the flaws in Mann's conclusions: "Today's NAS report reaffirms what I have been saying all along, that Mann's 'hockey stick' is broken."
Sen. Inhofe, also known as the cretin who tried to strip Metro's funding a few years ago, has continually repeated this and similar lines, to the point that quoting him does not add any substance to a story. Unfortunately, he is chairman of the Senate's Committee on Environment and Public Works. So his opinion counts more than anyone else's when it comes to public policy decisions. This is one of many reasons we would be better off with a Democratic majority.

Read the full NAS report if you want to see more detail.