Posted on 06/19/2008 3:33:44 PM PDT by blam
Greenland ice core analysis shows drastic climate change near end of last ice age
Caption: The North Greenland Ice Core Project camp. Credit: NGRIP
Temperatures spiked 22 degrees F in just 50 years, researchers say Information gleaned from a Greenland ice core by an international science team shows that two huge Northern Hemisphere temperature spikes prior to the close of the last ice age some 11,500 years ago were tied to fundamental shifts in atmospheric circulation.
The ice core showed the Northern Hemisphere briefly emerged from the last ice age some 14,700 years ago with a 22-degree-Fahrenheit spike in just 50 years, then plunged back into icy conditions before abruptly warming again about 11,700 years ago. Startlingly, the Greenland ice core evidence showed that a massive "reorganization" of atmospheric circulation in the Northern Hemisphere coincided with each temperature spurt, with each reorganization taking just one or two years, said the study authors.
The new findings are expected to help scientists improve existing computer models for predicting future climate change as increasing anthropogenic greenhouse gases in the atmosphere drive up Earth's temperatures globally.
The team used changes in dust levels and stable water isotopes in the annual ice layers of the two-mile-long Greenland ice core, which was hauled from the massive ice sheet between 1998 to 2004, to chart past temperature and precipitation swings. Their paper was published in the June 19 issue of Science Express, the online version of Science.
The ice cores -- analyzed with powerful microscopes -- were drilled as part of the North Greenland Ice Core Project led by project leader Dorthe Dahl-Jensen of the Centre for Ice and Climate at the Neils Bohr Institute of the University of Copenhagen. The study included 17 co-investigators from Europe, one from Japan and two from the United States -- Jim White and Trevor Popp from the University of Colorado at Boulder.
"We have analyzed the transition from the last glacial period until our present warm interglacial period, and the climate shifts are happening suddenly, as if someone had pushed a button," said Dahl-Jenson.
According to the researchers, the first abrupt warming period beginning at 14,700 years ago lasted until about 12,900 years ago, when deep-freeze conditions returned for about 1,200 years before the onset of the second sharp warming event. The two events indicate a speed in the natural climate change process never before seen in ice cores, said White, director of CU-Boulder's Institute for Arctic and Alpine Research.
"We are beginning to tease apart the sequence of abrupt climate change," said White, whose work was funded by the National Science Foundation's Office of Polar Programs. "Since such rapid climate change would challenge even the most modern societies to successfully adapt, knowing how these massive events start and evolve is one of the most pressing climate questions we need to answer."
Both dramatic warming events were preceded by decreasing Greenland dust deposition, indicating higher tropical temperatures and significantly more rain falling on the deserts of Asia at the time, said White. The team believes the ancient tropical warming caused large, rapid atmospheric changes at the equator, the intensification of the Pacific monsoon, sea-ice loss in the north Atlantic Ocean and more atmospheric heat and moisture over Greenland and much of the rest of the Northern Hemisphere.
"Here we propose a series of events beginning in the lower latitudes and leading to changes in the ocean and atmosphere that reveal for the first time the anatomy of abrupt climate change," the authors wrote. White likened the abrupt shift in the Northern Hemisphere circulation pattern to shifts in the North American jet stream as it steers storms around the continent.
"We know such events are in Earth's future, but we don't know when," said White. "One question is whether we can see the symptoms before big problems occur. Until we answer these questions, we are speeding blindly down a narrow road, hoping there are no curves ahead."
Each yearly record of ice can reveal past temperatures and precipitation levels, the content of ancient atmospheres and even evidence for the timing and magnitude of distant storms, fires and volcanic eruptions, said White. The cores from the site -- located roughly in the middle of Greenland at an elevation of about 9,850 feet -- are four-inch-diameter cylinders brought to the surface in 11.5-foot lengths, said White.
Source: University of Colorado at Boulder
Uh oh, I didn’t see the copyright. How much do I owe you?
No doubt Gore-Magnon man was to blame here...after all, Gore-Magnon's tried to alter their living conditions, but still increased their fire output by 10% just before this happened....
History repeats itself...just very, very slowly in this case...
My conclusion, exactly.
I use old Bud Lite bottle caps and a rubber band to chart climate change.
Science be damned. Whatever the data, it will be interpreted to prove that mankind is ruining the earth and must be brought to heel. Strict controls must be brought to bear. Perhaps birth control chemicals in the water and early euthanasia for folks over sixty who get sick. Mother earth must be protected at all costs from the viral infection of mankind.
Partial sun cross there.
Something else that might cause a rapid climate change in Greenland 10,000 years ago might be a pole shift. We’re overdue now for another.
Gore-Magnon man, good one.
The Younger dryas period about 9 to 10 thousand years ago, has been speculated to have been cause when some of the ice dams broke and cold water rushed to the North Atlantic creating the St. Lawrence. All of this cold water prevented the Gulf Stream from completing its warm course to Europe. It took a thousand years to resolve the situation.
Therefore the solution to global warming is to build a sea wall from North Carolina to divert the Gulf Stream. New York would have polar bears and Europe could ski year round.
Keep drilling deeper, until we hear “Largest oil and mineral reserves in history found underneath Greenland’s ice cap.”
Did somebody repossess Fred Flintstone’s dinosaur car?
So now we know how Algore uses so much power——to keep the Greenland ice cores frozen. Wouldn’t these guy’s conclusions require knowing that Greenland froze every year for a couple bazillion years? What if it warmed up for, oh, say, a couple thousand years every now and then and a couple feet of “evidence” slid into the ocean? I’m a little suspicious these ice-hole-drillers are “proving” more than they have evidence for?
beat me to it LOL. My thoughts exactly.
1) 14,000 years ago, or even 11,000 years ago - man was not contributing to global warming gases (if you consider the 0.28% that we DO contribute as a real factor - I don't).
2) We are in a WARM period RIGHT NOW. A relatively long warm period (thank goodness for civilization). We ARE coming to a turn in the road if the past cycles hold true. And based on the past information, it would be a turn downwards (in temperature). We're going to be caught with our pants down trying to stop global warming, when instead we should be preparing for all types of climate change. (Hot, cold, wet, dry, ....) Of course the best way to rapidly adapt to that is the old fashioned entrepreneurial way - not some plodding government program.
Just so. The politicization of science in America is the greatest tragedy I've observed in my lifetime.
Hope it takes its time, a rapid pole shift would be ...bad. There is evidence to support pole shift concept.
“I use old Bud Lite bottle caps and a rubber band to chart climate change”
YOU are officially my new “sarcasm hero”, just for that statement alone.
mrs
“This story is not true. We have been told now by the doom and gloomers that mankind causes climate change. They want us to believe there is some magical perfect climate that would exist if not for mankind. Without mankind, the world must have been perfection and climatically precise. Whatever could these authors be thinking?”
Hang on a minute. Just because the climate changed in the past without humans being the cause does not mean humans can not cause climate change now or in the future.
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