Polar Low, AMOC Shift May Further Complicate Future Of US, EU - But Research Just Getting Going
Summer and fall are hurricane season, but for the storms known as polar lows, prime time falls in the dead of winter, when frigid air blows off sea ice to collide with warmer, moister air in the North Atlantic. Polar lows are a lot smaller and weaker than hurricanes, they’re generally shorter-lived, and the only danger they generally pose is to shipping and oil rigs.
However, according to a new study in Nature Geoscience, the dozens of polar lows that roil the Greenland, Iceland and Norwegian seas every year may have an effect on the climate of North America and Europe. And if polar lows move northward with the changing climate, as some studies have predicted, winters in both places could become colder, even as the planet warms.
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As the planet warms, sea ice is likely to diminish in the Arctic — especially in summer, but also, as you go further south, in winter as well. “A couple of previous studies have shown that if the ice migrates northward, these storms could migrate northward as well,” said co-author Ian Renfrew, of the University of East Anglia, in the U.K. If that happens, their ocean-roiling, water-cooling effect on the AMOC would diminish and the current would presumably slow. That would mean less warm water and warm air for the U.S. East Coast and for Europe — and because water would back up like cars on a congested freeway, the New York-New Jersey region could experience greater sea-level rise by 2100 than the projected worldwide average.
This will be especially true if another effect kicks in. As melting ice caps and glaciers inundate the seas between Greenland and Norway with fresh water, the saltiness of those seas will diminish — and since fresh water is less dense than salt water, it will be even more difficult for surface water to sink for the return southward.
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http://www.climatecentral.org/news/arctic-storms-the-climate-danger-nobodys-talking-about-15363