CHICAGO, ILLINOIS—It’s not a secret that the Arctic Ocean is turning from white to blue as sea ice retreats. But a video compressing 25 years of satellite data into a single minute still drew gasps in a session here yesterday at the annual meeting of AAAS, which publishes Science. The movie, created late last year with data from satellites and buoys, shows how each year’s sea ice cover pulses like an amoeba, expanding and contracting with the seasons—and ending almost every summer a little smaller than the year before. The video shows one reason why: The ice is getting younger. The Arctic Ocean continually loses thick, old ice, the kind that easily survives a warm summer, as currents sweep it out the Fram Strait, east of Greenland. Because of warmer Arctic temperatures, little multiyear ice forms to replace what’s lost. Over 25 years, the proportion of the ocean covered by ice at least four years old has dwindled from 26% to 7%, while the remaining ice is mainly thin, the product of one winter. That quickly melts the following summer, leaving the ocean barer and bluer than before. To participants in the AAAS session, devoted to how the Arctic ice loss could affect everything from commerce to weather patterns to national security, the video was a call to action.
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(Video credit: NOAA Climate.gov; Mark Tschudi)