Fresh water from global warming could stop the Gulf Stream

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Fresh water from global warming could stop the Gulf Stream

Post by webearthonline »

In the news,

"Arctic Changes Could Halt Gulf Stream
Wednesday, January 25, 2012

Over the past 15 years, a mass of fresh water from ice melt has been building under the Arctic ice cap. The water is trapped under the Beaufort Gyre in the western Arctic, and presently represents about 10% of all the fresh water in the Arctic. It appears in the form of a bulge under the ice, and is kept in place by the permanent anti-cyclonic winds that blow around the gyre. The water is coming from melt-swollen Siberian rivers, and the bulge is growing by about six inches a year, meaning that billions of gallons of water are continuing to accumulate in it.

After the last ice age ended, there was a period of warming known as the Bolling-Allrod interstadial, which was suddenly ended by an intense period of cooling called the Younger Dryas. This cooling period struck both Europe and North America, returning them to glacial conditions for a period of about 1,300 years.

The Younger Dryas was caused by a flood of fresh water into the Arctic Ocean. This fresh water, in turn, caused the Gulf Stream to cease to flow, and when it stopped, extreme cold conditions returned. Until recently, it has been believed that the change took place over about a ten year period, but it is now known that the most dramatic alteration of climate unfolded in a single season, and, in some areas, in a matter of days. "

The fresh water that triggered the Younger Dryas came from the collapse of Lake Agassiz, which was glacial meltwater held back by a massive ice dam. There is probably at least as much fresh water under the ice cap now as there was in Lake Agassiz. It is prevented from flowing into the ocean by the strong counterclockwise winds around the gyre. However, these winds sometimes change direction, and if they do that for any length of time, it is possible that the water will be released, with a probable significant effect on the upper Gulf Stream, and therefore on the climate of the Northern Hemisphere, which could become colder for a protracted period.
weo
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