Atlantic Ocean warmth melts sea ice from below

Mixing waters may hasten arrival of ice-free Arctic Ocean summers

Arctic sea ice
Arctic sea ice is being melted by intrusions of warmer Atlantic Ocean water. @bberwyn photo.

Staff Report

In yet another sign that the balance of Earth’s climate system is being perturbed by global warming, scientists are documenting how a steady intrusion of water from the Atlantic is undermining sea ice in the Arctic Ocean.

The research, led by Igor Polyakov, a professor at the University of Alaska Fairbanks International Arctic Research Center, shows that the relatively warm  Atlantic Ocean water is a surprisingly powerful contributor to Arctic sea ice decline.

“This is a very important step toward a seasonal ice-free Arctic,” said Polyakov, explaining that the changes mean that summer sea ice could vanish sooner than expected.

After a decade of rapid sea ice decline, parts of the eastern Arctic Ocean have already been nearly ice-free by the end of summer. Up to now, currents from the Atlantic were deemed a small factor because the warmer water was capped by a colder surface layer. Without mixing,  the heat from the warmer water can’t come into contact with sea ice at the surface.

But the research shows how that dynamic is changing and that there is more mixing of layers in the Eastern Eurasian Basin, a major pathway for Atlantic water into the Arctic Ocean. That means more heat is being transferred to the Arctic sea ice on the surface.

Even before analyzing the data, the research team noticed that something was changing. They depend on solid sea ice to deploy their research buoys. During the 2015 expedition aboard the icebreaking research vessel Akademik Tryoshnikov, much of the sea ice was too rotten to support the buoys, Polyakov said.

“For the first time, we had a problem finding a suitable ice floe to deploy buoys. We spent several days trying to find such a floe.”

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