Posted on 01/10/2006 2:47:01 PM PST by blam
Broken ice dam blamed for 300-year chill
14:21 10 January 2006
NewScientist.com news service
Kurt Kleiner
A three-century-long cold spell that chilled Europe 8200 years ago was probably caused by the bursting of a Canadian ice dam, which released a colossal flood of glacial meltwater into the Atlantic Ocean.
Two new papers, using different computer models, show that the massive freshwater flood accounts for evidence of the sudden climate change, which cooled Greenland by an average of 7.4°C, and Europe by about 1°C. It was the most abrupt and widespread cool spell in the last 10,000 years.
Evidence for the cooling has been found in ice core samples, preserved pollen, evidence of shifting lake levels and ocean sediment. Some researchers think the cooling might have been caused by normal fluctuations in solar radiation.
In 1999 Don Barber, a geologist now at Bryn Mawr College in Pennsylvania, US, and colleagues suggested that the cooling was caused by flooding by glacial meltwater. Geological evidence shows that by about 11,000 years ago, retreating glaciers had left two huge freshwater lakes sprawling over Central Canada and parts of the northern US, bigger than all of today's Great Lakes combined.
Eventually, the lakes broke through an ice sheet that served as a dam and drained into Hudson Bay, and from there into the North Atlantic (Nature, vol 400, p 344).
Barber's idea was that the influx of fresh water changed salinity levels in the North Atlantic, and disrupted the thermohaline circulation – the currents that bring warm southern water north, helping to warm Europe and the Arctic regions.
"Strong confirmation"
In the new papers, one in the Proceedings of the National Academy of Sciences and the other in the current Quaternary Science Reviews, two teams of researchers using different computer models say that both models show that such a freshwater flood could shut down ocean circulation in a way that is consistent with temperature data from the time.
"We've shown the hypothesis generates the climate change that generates the data. It makes the story of the 8200-year event a much more well-rounded story," says Gavin Schmidt, a climatologist at NASA's Goddard Institute for Space Studies in New York City, US, a co-author of the PNAS paper.
"I would say it's a pretty strong confirmation of our understanding of that event," says Barber.
The work could have implications for the modern climate. Some researchers suggest that global warming and glacial melting might one day change ocean salinity enough to cause a similar disruption in ocean currents.
Journal references: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0510095103), Quaternary Science Reviews (vol 25, p 63)
I read about that in Sports Illustrated.
The dam was taken out by an errant stone hurled during that year's national curling championships.
Caused one helluva mess.
Darn socialist government banned curling and the Canucks had to play with much smaller stones called "pucks".
you can see the groves in the rocks in the exposed bedrock in Central Park and the Bronx Zoo....
the one in Idaho/Washington produced the scab lands...quite an event.
I thought it was fascinating, and there was a good bit of information that I didn't know. But I kept waiting for the global warming lesson and I wasn't disappointed. As my wife said, the "little ice age" must have been caused by all the coal burning factories they had in the 1200s.
Come and see my stromatolite formation that is even bigger than the "famous" petrified gardens in Saratoga...
(and it's a 1/2 million years older)
The last time I was out in Alberta I took a tour in the Canadian Rockies, and the tour guide described a recent hike up into the mountains. He said he found sea shells and other signs of ocean creatures near the top of one of the mountains -- 12,000 feet above sea level.
The top of Mt. Everest is marine limestone, formed at the bottom of an ancient ocean that used to exist between India and Asia.
You may be describing the same event as the article...
Possibly -- except the article describes water flowing north into Hudson Bay, instead of south into the Atlantic Ocean via the Hudson River.
Junk science.
In far southern Oregon, on Interstate 5, at the peak of Ashland pass, they had blasted oout about 200 feet of rock on both sides of the road.
It is sedimentary, and if you go about twenty miles south, you get into the slates and igneous stuff near Shasta.
I saw some odd forms in the rock layers one day and busted them out.
They are roots. Petrified roots in the rock layers.
At 4400 feet. And still rising.
Why did these geniuses not explain the source of the "global warming" and "galcial melting" that accounted for the data they claim to explain? Or did rundy just miss them detailing the fact that the inhabitants of the North American continent 8200 years ago had gone berzerk on their air polluting snow mobiles, SUV's and industrial factories spewing out tons of pollutants...blah, blah, blah.
The fact this happend NATURALLY thousands of years ago does not provide this brain children a clue that what is happening now might just be "due to" NATURAL events, not man's (mankind's) doings.
I expell a great big
ICE AGE!!!!
I can't tell if it's junk science because it's what happened in a cartoon movie for children, or if cartoon movies for children suddenly have become more impressive since they beat science to the punch.......
At 33 degrees you get rain. At 32 degrees you get snow. A large accumulation of snow reflects sunlight and further lowers the temperature. The difference between "normal" and "ice age" is often as little as 7 degrees. The key issue is whether more snow falls and accumulates vs melting off. A steady accumulation, even at a slow rate, is the mark of an ice age.
Missoula lake. The flooding created the scab lands in Washington state. Apparently it broke and reformed several times.
I believe that's also how the Wisconsin Dells were formed.
Has Pat Robertson blamed anyone for this disaster?
It's not the coldness of the winter that makes ice ages, it's whether the summer is warm/long enough to melt the winters' accumulations.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.