- Talk about a climate change: A University of Illinois
at Chicago professor says he has found new evidence that a massive meltdown
of polar ice 8,200 years ago put North America into a deep freeze for a
century.
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- The "most dramatic climate change in the last 10,000
years" followed a flood of fresh water from a glacial reservoir into
the salty water of the Gulf Stream, which controls our continent's weather.
That led to a 43-degree temperature drop, said UIC's Torbjorn
Tornqvist.
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- His report on earth core samples that indicate an abrupt
jump in sea levels caused by the colossal flood will appear Saturday in
an online issue of Geophysical Research Letters. Scientists believe the
flood's source was a glacial reservoir called Lake Agassiz, holding twice
the volume of the Caspian Sea in Eurasia, the world's largest inland
sea.
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- According to this theory, all that fresh water gushed
into the North Atlantic. There it mixed with the salty waters of the Gulf
Stream.
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- Now less salty and less buoyant, the warm surface water
sank, cooling the stream that ordinarily carries tropical waters to this
continent.
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- The result? A temperature plunge of 43 degrees Fahrenheit
that may have lasted 100 years or more.
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- At a time when scientists are focused on global warming,
the "take-home message" is that climate change is a complicated
phenomenon featuring abrupt swings toward both ends of the
thermometer.
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- Tornqvist and his students found evidence of the
millennia-old
freshwater deluge while taking core samples of earth in the Mississippi
Delta. "We were studying the loss of coastal wetlands but found
something
much more interesting," he said.
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- His team discovered deep core samples of peat that
radiocarbon
dating pegged at around 8,200 years, when the so-called "8.2
Event"
occurred. Made up of decayed plant material in soggy ground, peat forms
as sea levels rise.
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- His findings establish the first sea-level record
corresponding
to the big flood.
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- "The $64 million question is how much fresh water
was released," the professor said. "My suspicion is that the
only way is looking at sea levels."
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- Could the 8.2 Event happen again, as in the disaster
movie "The Day After Tomorrow"?
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- "We don't have a Lake Agassiz now," Tornqvist
said. But in Greenland, where the first evidence of the great flood was
found, the ice sheet is melting at an accelerating rate. And global warming
puts more moisture into the air, producing more rain and, in turn, fresher
ocean water.
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- "It depends on how sensitive the North Atlantic
is to that kind of process," Tornqvist said. "One possibility
is that global warming could lead to this type of surprise but only affect
part of the world."
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- Copyright 2004, Digital Chicago Inc.
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- http://www.suntimes.com/output/news/cst-nws-flood13.html
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