A slight adjustment to U.S. temperature records has bumped 1998 as the hottest year in the nation's history and made the Dust Bowl year...

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A slight adjustment to U.S. temperature records has bumped 1998 as the hottest year in the nation’s history and made the Dust Bowl year of 1934 the new record holder, according to NASA.

The reranking did not affect global records, and 1998 remains tied with 2005 as the hottest year on record worldwide, climatologist Gavin Schmidt of NASA’s Goddard Institute for Space Studies in New York said Tuesday.

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.”

The reranking occurred Aug. 7 with little fanfare, but it touched off a firestorm among climate bloggers and commentators, some of whom seized upon the new rankings as evidence that global warming is a hoax.

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The uproar was really “much ado over nothing,” Schmidt said.

The brouhaha was triggered Aug. 4 when Steve McIntyre of the blog Climateaudit.org e-mailed NASA scientists to point out an unusual jump in temperature data from 1999 to 2000.

When researchers checked it out, they found that the agency had merged two data sets that had been incorrectly assumed to match.

When the data was 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 previously had been recorded as 0.02 degrees warmer than 1934, was now 0.04 degrees cooler.

Schmidt noted that researchers had always known that the difference between the two years was so small that it was virtually impossible to rank them.

With the new rankings, four of the 10 warmest years in the United States occurred in the 1930s.

“But, in big-picture terms, the adjustments didn’t change anything for global-warming or climate-change issues,” Schmidt said. “The changes were pretty negligible.”

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