Skip to comments.Broken Ice Dam Blamed For 300-Year Chill
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
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.
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)
They say the water broke out to the north rather than down the St Lawrence and Mississippi. Is that what you get from this?
But they were 'Sport Utility Ice Dams'.
I believe this period is known as the Older Dryas.
I like how the author slipped in the "global warming" comment. Jeez.
Oh no! A whole degree cooler!
Yes and that could make sense too.
The evidence for this type of event was found out along the continental shelf off the coast of New Jersey, in the form of large rocks scattered on the ocean floor that are indigenous to the Adirondack Mountains -- hundreds of miles away from the mouth of the Hudson River.
"We shoulda signed the Kyoto Treaty!"
Was global warming or global cooling associated with the Ice Age? Could it not have been more of a regional phenomenon?
Just like the History Channel's show on the "little ice age" that was on this past Sunday. Interesting show, but the political agenda revealed at the end called into question everything that had previously been said.
Three words: Rove, Cheney & Bush!
and of course the Hudson canyon remains today under the ocean wending along.......a trench that goes hundreds of miles out into the Atlantic before it ends at the dropoff of the continental shelf.
The fault of Bush's environmental policies.
Yes. They were dammed up and broken a couple times. The biggest flood went north into the Hudson Bay...the ice sheet that was on the largest lake, became boyant, broke and slid into Hudson Bay causing gawd awful tsunamis.
Once this 'chill' period was over, the Ice Age melt resumed unhindered.
It was just after this period that the Mediterranean reflooded and eventually broke the dam at the Bosporus and flooded the Black Sea.(Noah's Flood?)
I saw some of that and found it quite interesting. I guess I am fortunate I missed the ending.
There's alot of interesting geology in New York. There is a place near where I grew up where the shale bedrock is exposed, and you can see the grooves cut in the rock from the glaciers.
Alot of New York was at one time, submerged. Some of the largest salt deposits in the world are buried in the western part of the state.
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.
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
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.
Different events. I believe the one out west that carved the Snake River happened after this chill.
The Oldest Dryas was about 18,000 ya, IIRC.
The Younger Dryas was dated about 13,000 - 11,500 ya and de4scribed in Wikipedia as follows:
The prevailing theory holds that the Younger Dryas was caused by a significant reduction or shutdown of the North Atlantic thermohaline circulation in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. This theory does not explain why South America cooled first.
The event described in the article was 8,200 ya but seems to have about the same cause as the Younger Dryas. It would seem that this might be a recurring type of event happening as the glacial ice sheets retreat.
ice age is not a movie just for kids, it's beats the junk science with a stick
I am not a one of the environmental nuts, I know the planet and solar system does whatever it is scheduled to do. Something like an immediate drop of several degrees Centigrade would be awful. I am sure many Canadians wouldn't be happy, nor many of our northern brothers. Heck, they would all come down here and we wouldn't be happy. Disaster.
There was once on Discovery a talk about some eggheads who went to some lake in Canada and took core samples of the sediments.
From decoding the pollens and sizes of the sediments they were able to determine how long it took one of the ice age periods to go from temperate climate to full-bore ice age glaciation.
Less than a blink of an eye in geologic terms.
I would very happy - think how long the ski season would be, for one; how nice Phoenix and the Havasu Lakes would be with a more moderate summer; as well as the entire beautiful, but currently too hot Mexican Desert. I think there'd be plenty of room for all the Canadians that wanted to come.
Pat's circuit breaker tripped last week; it'll reset itself in a month or so.
You are referring to Glacial Lake Missoula. It was a tiny fraction of the size of the lake referred to in the article. I've seen an artist's rendering of this lake, and it covered most of Saskatchewan, Manitoba, North Dakota, and parts of Alberta, Minnesota, and South Dakota. It was huge.
I knew about this years ago. The National Academy of Sciences is just now finding out?