Thursday, May 10, 2018

Alien Waters:  Neighboring Seas Are Flowing into a Warming Arctic Ocean

The “Atlantification” and “Pacification” of the Arctic has begun.  As warmer waters stream into an increasingly ice-free Arctic Ocean, new species — from phytoplankton to whales — have the potential to upend this sensitive polar environment.

Melt pools atop sea ice in the Arctic Ocean in August 2009. (C0redit: Pablo Clemente-Colon / National Ice Center) Click to Enlarge.
Above Scandinavia, on the Atlantic side of the Arctic Ocean, mackerel, cod, and other fish native to the European coast are migrating through increasingly ice-free waters, heading deeper into the Arctic Basin toward Siberia.  Thousands of miles to the west, above Alaska, kittiwakes and other polar seabirds are being supplanted by southern birds following warm waters streaming north through the Bering Strait.  And midway between, above Canada, sea ice-avoiding killer whales from the Atlantic are increasingly making themselves at home in a thawing Arctic.

As the Arctic heats up faster than any other region on the planet, once-distinct boundaries between the frigid polar ocean and its warmer, neighboring oceans are beginning to blur, opening the gates to southern waters bearing foreign species, from phytoplankton to whales.  The “Atlantification” and “Pacification” of the Arctic Ocean are now rapidly advancing.  A new paper by University of Washington oceanographer Rebecca Woodgate, for example, finds that the volume of Pacific Ocean water flowing north into the Arctic Ocean through the Bering Strait surged up to 70 percent over the past decade and now equals 50 times the annual flow of the Mississippi River.  And over on the Atlantic flank of the Arctic, another recent report concludes that the Arctic Ocean’s cold layering system that blocks Atlantic inflows is breaking down, allowing a deluge of warmer, denser water to flood into the Arctic Basin.

The Arctic Ocean, and its connections to the Pacific and Atlantic oceans. Yale Environment 360 / Google Earth) Click to Enlarge.
Because the oceanographic conditions in the Atlantic and Pacific sectors of the Arctic are distinct, the physical mechanisms behind these widespread changes differ.  But scientists say that the growing intrusions on both sides of the Arctic Ocean are driving heat, nutrients, and temperate species to new polar latitudes — with profound impacts on Arctic Ocean dynamics, marine food webs, and longstanding predator-prey relationships.

Read more at Alien Waters:  Neighboring Seas Are Flowing into a Warming Arctic Ocean

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