Arctic sea ice rebounded in 2013 from last year’s record melting season, though scientists warned that the long-term trend is for the ocean to become increasingly ice-free in the summer.
The sea ice covering the Arctic Ocean melts every summer through mid-September before freezing over winter. This year, the ice cover fell to 5.1 million square kilometers (1.97 million square miles) at its lowest, the U.S. National Snow and Ice Data Center at the University of Colorado at Boulder said today in an e-mailed statement. That’s 50 percent more than 2012’s minimum extent, the lowest in data going back to 1979.
“While this is a very welcome recovery from last year’s record low, the overall trend is still decidedly downwards,” NSIDC Director Mark Serreze said in the statement. “We could be looking at summers with essentially no sea ice on the Arctic Ocean only a few decades from now.”
Researchers say Arctic sea ice retreat is one of the most visible signs that the planet’s climate is warning. The increased melting is opening the Arctic Ocean to more shipping and exploration for oil and minerals. At the same time, it serves to multiply climate change, because the dark exposed ocean absorbs more of the sun’s heat than the reflective ice.
This year’s summer low was reached on Sept. 13, before the ocean began to freeze again, the NSIDC said. Its data are preliminary and it will publish a full analysis next month.
“It’s not in any way a recovery, it’s just a rebound from last year,” Walt Meier, a research scientist with the U.S. National Aeronautics and Space Administration, said in an interview from Greenbelt, Maryland earlier this month.
“There are two schools of thought. One is that there’s a tipping point where you’ll go off a cliff and head very rapidly towards ice-free summers,” Meier said. “Last year was a data point that hinted at that. And there’s another school that says it’ll be more of a linear trend with ups and downs,” he said. “I’m thinking it’ll be more linear -- but an accelerating linear trend.”