Friday, 31 August 2018

Research: Arctic ice is melting from below


Scientists find pocket of warm water trapped under Arctic with potential to melt entire ice pack
Pocket of water blown from hundreds of miles away could leave Canadian Basin ice-free for much of the year


30 August, 2018


A warm region of water trapped deep below the surface of the Arctic seas north of Canada has the potential to leave the entire area devoid of ice.
Scientists have discovered warmer water that originated hundreds of miles away has penetrated deep below the ice pack’s surface.
Vast swathes of the polar expanse are changing dramatically every year – with sea ice vanishing far earlier in the season that it used to, and ships beginning to take advantage of the newly ice-free oceans.
This effect could be exacerbated in one of the Arctic Ocean’s major regions – known as the Canadian Basin – by the influx of warmer water that is currently stored underneath it.
Using data collected over the past 30 years, researchers at Yale University and Woods Hole Oceanographic Institution saw the “heat content” of the area had doubled during this period.
They were able to trace this water to the Chukchi Sea further south, where the regional decline in sea ice has left the water very exposed to the summer sun.
After heating up, this water has been driven north by Arctic winds, but has remained below the top layer of water – resulting in a high-temperature zone trapped far beneath the ice pack.
This means the effects of sea-ice loss are not limited to the ice-free regions themselves, but also lead to increased heat accumulation in the interior of the Arctic Ocean that can have climate effects well beyond the summer season,” said Yale geologist Professor Mary-Louise Timmermans, who led the study.
Presently this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year.”

The Arctic is warming at twice the rate of the global average, and year after year bodies like the US National Oceanic and Atmospheric Administration report record-breaking climate extremes in the region.
Last year saw the lowest ever measurements for maximum winter sea ice cover across the Arctic, and the second warmest air temperatures on record.
These changes have caused havoc for the people and animals that inhabit the polar region.
Almost all the ice covering the Bering Sea in the northern Pacific Ocean vanished a month early this year, impacting the hunting and fishing activities of the inhabitants of western Alaska.
The recent breakup of the “last holdout” of thickest ice in the Arctic was described as “highly unusual” by scientists.
This breakup is an unsettling sign of climate change, and experts warned that it would likely have a serious impact on the region’s polar bears and seals.




Arctic sea ice isn’t just threatened by the melting of ice around its edges, a new study has found: Warmer water that originated hundreds of miles away has penetrated deep into the interior of the Arctic.

That “archived” heat, currently trapped below the surface, has the potential to melt the region’s entire sea-ice pack if it reaches the surface, researchers say.
The study appears online Aug. 29 in the journal Science Advances.

We document a striking ocean warming in one of the main basins of the interior Arctic Ocean, the Canadian Basin,” said lead author Mary-Louise Timmermans, a professor of geology and geophysics at Yale University.

The upper ocean in the Canadian Basin has seen a two-fold increase in heat content over the past 30 years, the researchers said. They traced the source to waters hundreds of miles to the south, where reduced sea ice has left the surface ocean more exposed to summer solar warming. In turn, Arctic winds are driving the warmer water north, but below the surface waters.

This means the effects of sea-ice loss are not limited to the ice-free regions themselves, but also lead to increased heat accumulation in the interior of the Arctic Ocean that can have climate effects well beyond the summer season,” 
Timmermans said. “Presently this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year.”

The co-authors of the study are John Toole and Richard Krishfield of the Woods Hole Oceanographic Institution.

The National Science Foundation Division of Polar Programs provided support for the research.

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