Thursday, June 28, 2018

A Huge Stretch of the Arctic Ocean Is Rapidly Turning Into the Atlantic.  That’s Not a Good Sign

The northern Barents Sea shifts over to an Atlantic climate and becomes sea-ice free. (Credit: Sigrid Lind) Click to Enlarge.
Scientists studying one of the fastest-warming regions of the global ocean say changes in this region are so sudden and vast that in effect, it will soon be another limb of the Atlantic Ocean, rather than a characteristically icy Arctic sea.

The northern Barents Sea, to the north of Scandinavia and east of the remote archipelago of Svalbard, has warmed extremely rapidly — by 2.7 degrees Fahrenheit just since the year 2000 — standing out even in the fastest-warming part of the globe, the Arctic.

“We call it the Arctic warming hot spot,” said Sigrid Lind, a researcher at the Institute of Marine Research in Tromso, Norway.

Now Lind and her colleagues have shown, based on temperature and salinity measurements taken on summer research cruises, that this warming is being accompanied by a stark change of character, as the Atlantic is in effect taking over the region and converting it into a very different entity.

Their results were published this week in Nature Climate Change by Lind and two colleagues at Norway’s Institute of Marine Research and University of Bergen.  They underscore that the divide between the Atlantic and the Arctic isn’t just a geographical one — it’s physical in nature.

While the Southern Barents is milder, the northern Barents has — until recently — had all the characteristics of an Arctic sea.  It featured floating sea ice that, when it melted, helped to provide an icy, freshwater cap atop the ocean.  This kept internal heat from escaping to the atmosphere, and also kept the ocean “stratified” — cold, fresher waters in the upper part of the ocean and warmer, Atlantic-originating waters down below.

This situation, which occurs in much of the Arctic, was reinforced by the fact that freshwater is less dense than salt water, preserving stratification.

But that’s changing.  Less sea ice is floating down through the northern Barents Sea from higher Arctic latitudes, the research shows.

Read more at A Huge Stretch of the Arctic Ocean Is Rapidly Turning Into the Atlantic.  That’s Not a Good Sign

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