A slight adjustment to U.S. temperature records has bumped 1998 as the hottest year in the country's history and made the Dust Bowl year of 1934 the new record holder, according to NASA.
But the re-ranking did not affect global records, and 1998 remains tied with 2005 as the hottest year on record, climatologist Gavin A. 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 re-ranking occurred Aug. 7 with little fanfare, but it touched off a firestorm among climate bloggers and commentators, who took the new rankings as evidence that global warming was a hoax.
But 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 pointing out an unusual jump in temperature data from 1999 to 2000.
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.
Schmidt said that researchers had always known that the difference between 1934 and 1998 was so small, it was virtually impossible to rank them.
With the new rankings, four of the 10 warmest years in the United States occurred during 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."