Much Ado About Nothing?

NASA data for average annual temperatures in the lower 48 states received a small downward adjustment earlier this month, after blogger Stephen McIntyre of climateaudit.org pointed out an error to NASA in its numbers. No big deal, except Mr. McIntyre also blogged that the error altered rankings for the warmest years on record since 1895 — key fodder in the global-warming debate. The warmest year became 1934, rather than 1998, although the temperature difference was small enough to be considered statistically meaningless.Skeptical bloggers took the opportunity to denounce global warming as fabricated, and talk-show host Rush Limbaugh quickly called the data adjustment “proof” that global warming was a man-made notion, according to several publications. Meanwhile, the mainstream press took pains to emphasize the fact that robust evidence of global warming remains available:

Thomas H. Maugh’s article in the L.A. Times said that the corrections resulted in a decrease of 0.27 degrees Fahrenheit in yearly temperatures in the lower 48 since 2000 and a smaller decrease in earlier years. 1998, which had been 0.02 degrees warmer than 1934, re-ranked 0.04 degrees cooler. (Not exactly enough to make you go put on a hat and gloves.) He also mentioned that the adjustment didn’t affect global records, and that 1998 remains tied with 2005 as the hottest year on record.

Andrew C. Revkin noted in the New York Times that Mr. McIntyre and James E. Hansen of NASA had traded a few choice barbs online in their debate — but that both agreed on the “merit of shifting away from energy choices that contribute heat-trapping greenhouse gases to the atmosphere,” and that the global temperature trend remains unaffected.
The adjustment did affect global temperatures, though only by some 0.03 degrees. That may not sound like much, but its 4% of all warming recorded so far (0.75c). That’s a pretty huge adjustment. In one stroke it erased more “warming” than Kyoto would have ever done.