Was 1998 the hottest year in United States history, as most reporting on climate change has presumed? Or was that record set back in 1934 before "global warming" became a scary household phrase?
A corrective tweak to National Aeronautics and Space Administration's formulation shows that the hottest year on record in the US indeed was back during the Dust Bowl days.
But does this mean that all the concern about global warming being a relatively recent phenomenon tied to carbon-belching power plants and hulking SUVs is a bunch of Al Gore hooey?
Climate change skeptics and their cheering section among conservative bloggers and radio shoutmeisters think so – even though most scientists say, no, the tweak is not a big deal and overall trends are in the direction of toastier days around the globe.
The controversy began "when Steve McIntyre of the blog Climateaudit.org e-mailed NASA scientists pointing out an unusual jump in temperature data from 1999 to 2000," reports The Los Angeles Times.
"When researchers checked, they found that the agency had merged two data sets that had been incorrectly assumed to match. When the data were corrected, it resulted in a decrease of 0.27 degrees Fahrenheit in yearly temperatures since 2000 and a smaller decrease in earlier years. That meant that 1998, which had been 0.02 degrees warmer than 1934, was now 0.04 degrees cooler."
Put another way, the new figures show that 4 of the 10 warmest years in the US occurred during the 1930s, not more recently. This caused a stir among those critical of the push to stem human-induced climate change.
"Conservative radio talk show host Rush Limbaugh used reports of the revisions to argue that climate change is a hoax perpetrated by scientists with liberal agendas," reported The Washington Post.
"We have proof of man-made global warming," Limbaugh said on his show…. "The man-made global warming is inside NASA. The man-made global warming is in the scientific community with false data."
Blogger Steve McIntyre, who started the controversy, lives in Canada. His hometown newspaper, The Toronto Star, headlined its story "Red faces at NASA over climate-change blunder."
"They moved pretty fast on this," McIntyre said. "There must have been some long faces."
Still, McIntyre called his finding "a micro-change," and others agree. For one, the reranking didn't affect global records, and 1998 remains tied with 2005 as the hottest year on record, the Los Angeles Times notes, quoting climatologist Gavin Schmidt of NASA's Goddard Institute for Space Studies in New York.
"The data adjustment changes 'the inconsequential bragging rights for certain years in the U.S.,' he said. But 'global warming is a global issue, and the global numbers show that there is no question that the last five to 10 years have been the hottest period of the last century.' "
A main target of criticism over the data shift is James Hansen, director of the Goddard Institute at NASA and a frequently quoted expert on climate change. On his website, Dr. Hansen explained the reasons for the change, and he played down its importance.
"How big an error did this flaw cause?... The effect on U.S. average temperature is about 0.15°C beginning in 2000. Does this change have any affect ... on the global warming issue? Certainly not…. What we have here is a case of ... contrarians who present results in ways intended to deceive the public into believing that the changes have greater significance than reality. They aim to make a mountain out of a mole hill."
Meanwhile, evidence of global warming continues to mount. Citing a new study by researchers at the University of East Anglia, The Guardian newspaper reports that "some tipping points for climate change could be closer than previously thought."
"In drawing together research on tipping points, where damage due to climate change occurs irreversibly and at an increasing rate, the researchers concluded that the risks were much greater than those predicted by the latest report by the Intergovernmental Panel on Climate Change (IPCC)."
Is the issue settled? Far from it, says Roy Spencer, a principal research scientist for the University of Alabama, who describes himself as "skeptical of the claim that global warming is mostly manmade."
Blogging on TCSDaily.com Dr. Spencer writes:
"In case you hadn't noticed, the global warming debate has now escalated from a minor skirmish to an all-out war…. In the last year or so, more and more scientists have been coming out of the closet and admitting they've had some doubts about this whole global warming thing."