Nature - Scientific Study Pinpoints Location Of Sudden Ice Age 11,000 BCE

[hatrack]

"The study, published in the June 2 issue of Nature, pinpoints the exact location where freshwater generated by the melting of the massive Canada-wide Laurentide ice sheet entered the global ocean and caused the Younger Dryas cold reversal, a frigid period where the planet temporarily plunged into ice age conditions. Contrary to previous thinking, the study shows that this meltwater entered the Arctic Ocean rather than the Atlantic and the point of entry was through the MacKenzie River. As the freshwater - lighter due to its lack of salt content - flowed into the ocean it was transported across the pole into the North Atlantic where it shut down the process whereby heavy surface water sinks into the abyss and leads to a warming of the northern hemisphere.

While the Younger Dryas cold reversal occurred just as the Earth was emerging from the most recent ice age, a rapid meltback of the Greenland ice sheet - another large accumulation of land ice adjacent to the North Atlantic Ocean - could theoretically contribute to another such shutdown.

"Greenland contains enough ice to raise sea level by about seven metres if it were all to melt," says the study's co-author University Professor Richard Peltier of U of T's Department of Physics. "If it were to melt very quickly we could easily have a similar event, so the question is just how Greenland will react to the ongoing warming due to the increasing concentration of atmospheric greenhouses gases. How probable this is remains an open question."

To pinpoint the location of where the Younger Dryas event occurred, Peltier and his co-author, physic's research associate Lev Tarasov, used the University of Toronto Glacial Systems Model (GSM) - a model that produces a three-dimensional view of the evolving ice-sheet as it expands and contracts over the North American continent in response to climate variations. The model also analyses how the shape of the Earth is affected by the evolution of the heavy ice loads. As the continental ice melted, a huge amount of deglaciation derived freshwater was added to the oceans. At the time of Younger Dryas onset the routing of this meltwater was into the Arctic Ocean. "In considering the issue of climate change, many people imagine that this could only happen very gradually," says Peltier. "This event shows that our climate could change extremely rapidly and with very dramatic effect."

EDIT

http://www.physorg.com/news4779.html

[aquart]

1. Didn't they find a frozen mammoth with flowers in its stomach?

Flash frozen, as it were?

[HawkerHurricane]

2. Yes, and no

The mammoth had died in a mudslide, then frozen shortly after.

[Dogmudgeon]

3. Plus, this was a quick warm-up period

Pre-ice-age data graphs usually show some kind of temperature spike right before the ice age kicks in; our current era of global warming has produced a temperature spike that is about as big as the last one. There is also a similar CO2 spike -- it was about 450 ppm during the last warm-up, compared to about 400 ppm right now (200-300 ppm seems to be "normal").

The Younger-Dryas was a cold spell, but it was similar since it was a spin-off of what ended the ice age.

As for the mammoth -- the Berezovka Mammoth -- yes, it died and then was covered by a mudslide, but as usual, there are elements of both the mundane and the extraordinary in it. The freezing did happen quickly, though it wasn't a flash-freeze event. It fits in well with a climate in flux and producing temperature extremes. But it's still a lot less unusual than it was once thought -- though that may be bad news for the fauna that replaced the mammoths (namely, we humans).

--p!

[Strelnikov_]

4. "If it were to melt very quickly we could easily have a similar event . ."

Greenland contains enough ice to raise sea level by about seven metres if it were all to melt," says the study's co-author University Professor Richard Peltier of U of T's Department of Physics. "If it were to melt very quickly we could easily have a similar event, so the question is just how Greenland will react to the ongoing warming due to the increasing concentration of atmospheric greenhouses gases. How probable this is remains an open question.

I would say the oceans and connected seas rising 23 ft. would be quite an 'event' in itself.