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The Beaufort Gyre & the Great Salinity Anomaly.

  • 13-12-2017 9:01pm
    #1
    Registered Users Posts: 2,837 ✭✭✭ Pa ElGrande


    How a Wayward Arctic Current Could Cool the Climate in Europe
    December 11, 2017
    The Beaufort Gyre, a key Arctic Ocean current, is acting strangely. Scientists say it may be on the verge of discharging a huge amount of ice and cold freshwater that could kick off a period of lower temperatures in northern Europe.

    For millennia, the Beaufort Gyre — a massive wind-driven current in the Arctic Ocean — has been regulating climate and sea ice formation at the top of the world. Like a giant spinning top, the gyre corrals vast amounts of sea ice. Trapped in this clockwise swirl, the ice has historically had more time to thicken than it generally does in other parts of the Arctic Ocean, where currents such as the Trans Polar Drift transport the ice into the warmer north Atlantic more rapidly. In this way, the Beaufort Gyre — located north of Alaska and Canada’s Yukon Territory — has helped create the abundant layers of sea ice that, until recently, covered large parts of the Arctic Ocean year-round.
    <snip>
    The first confirmation of the Beaufort Gyre’s existence came in the 1950s when Soviet scientists conducted research in the region. Carmack first visited the gyre in 1971. At that point, the gyre had weakened and had set in motion the Great Salinity Anomaly.
    <snip>
    A similar event, known as the Great Salinity Anomaly, occurred from the late 1960s into the 1970s, when a surge of water out of the Arctic Ocean freshened and cooled the top half-mile of parts of the North Atlantic. According to British oceanographer Robert R. Dickson, the Great Salinity Anomaly represented one of the most persistent and extreme variations in global ocean climate observed during the past century. The surge of ice and freshwater cooled Northern Europe dramatically and disrupted the North Atlantic food chain, which, in turn, caused a collapse of the lucrative herring fishery. Between 1951 and 2010, as many as eight of 18 exceptionally cold European winters occurred during the period of the Great Salinity Anomaly.
    <snip>
    During the second half of the 20th century — and, most likely, earlier — the gyre adhered to a cyclical pattern in which it would shift gears every five to seven years and temporarily spin in a counter-clockwise direction, expelling ice and freshwater into the eastern Arctic Ocean and the North Atlantic. But for more than a dozen years, this carousel of ice and, increasingly, freshwater has been spinning faster in its usual clockwise direction, all the while collecting more and more freshwater from three sources: melting sea ice, huge volumes of runoff flowing into the Arctic Ocean from Russian and North American rivers, and the relatively fresh water streaming in from the Bering Sea.

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