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As Arctic sea ice vanishes at an alarming rate, scientists have reported a surprising finding in Antarctica. There, sea ice seems to be expanding.
A new study, however, suggests that Antarctic sea ice might not be expanding as much as previously thought. According to this view, the trend toward expansion might be an error introduced by a recalibration of how satellite data is processed.
"This ostensibly minor update in 2007 that was not believed to have caused any notable difference in the trend caused this big jump," said study researcher Ian Eisenman, who studies climate dynamics at the Scripps Institute of Oceanography at the University of California, San Diego.
Eisenman's view is contested, not least by the scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who developed the algorithm that is being criticized in the new study.
"The apparent expansion is real and not due to an error in a previous data set uncovered by the Eisenman et al paper," that scientist, NASA's Josefino Comiso, wrote in a response to the new study that he sent to Live Science. "That error has already been corrected and the expansion being reported now has also been reported by other groups as well using different techniques."
Eisenman said his findings have introduced two possibilities. One is that the new, updated dataset is wrong. In that case, Antarctic ice would be expanding, but not nearly as quickly as scientists believed — the seeming trend would be largely a side effect of the data-processing change.
Alternatively, the new dataset might be right, with the error lurking in the pre-2007 version. In that case, studies that have used that version of the data would need to be reassessed, Eisenman said.
"Whatever the root of this ends up being, I highly doubt it was anything egregious," he said. "We're working with nuanced datasets here, trying to make long-term measurements with multiple instruments, none of which are directly measuring what we want."
—Stephanie Pappas, Live Science
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