Greenland glacial lakes suddenly disappear

[pscot]

http://www.businessweek.com/bwdaily/dnflash/content/apr2008/db20080417_425304.htm?chan=top+news_top+news+index_businessweek+exclusives

In poring over satellite images, researchers noticed that large lakes form on the surface of the glaciers during the summer. Those lakes then suddenly disappear. "We see these things come and go," says Sarah Das, glaciologist at the Woods Hole Oceanographic Institution in Woods Hole, Mass. One possibility was the lakes simply drain into rivers on the surface. Or, scientists theorized, the water might generate enough pressure to crack the 3,000-foot-thick ice all the way to bedrock, pouring down through the ice.

A team led by Das and Ian Joughin of the University of Washington set out to prove which idea was correct. They flew to an area of glaciers with lakes, and set up camp on the ice. Then they installed an array of instruments. They put sensors in a lake 2½ miles wide to measure the changes in the amount of water it held. They deployed seismometers to detect rumbles in the ice, and put global-positioning units on the ice to chart its movement. They left the instruments in place when they left the study area, and waited.

Ice Disappearing Faster Than We Thought

It wasn't a long wait. "The lake drained about 10 days after we were there," Das says. When they went back, gathered up the instruments, and began to look at the data, it was clear that the crack theory was correct. The water had indeed rushed down to the bedrock. It had spread out under the ice, and raised the huge ice sheet by more than three feet. But there was a also a surprise: It happened in a relative flash. "The entire lake drained in about two hours," says Das. "It was a much more catastrophic drainage than we expected." The volume of water flowing down to bedrock matched the torrent over Niagara Falls. That realization led the team to ditch plans to explore other, still-intact lakes aboard a rubber boat. "We decided we'd leave the boat in its crate," laughs Das.

The little slide show is interesting.

[XemaSab]

1. .

[emmadoggy]

2. Yikes.

[lurky]

3. Why am I hearing about this from Business Week?

Everyone else too busy with "Bitter Gate" to notice that things are much worse than we feared? This is not some abstract, Carl Sagan vs. Stephen Hawking science debate anymore -- this is immediate.

These stories need to be taken out of the science-section ghetto and placed on the front page.

[Delphinus]

4. Why *isn't* it:

'run for the hills, we are doomed'? (From the article: Down at the bedrock, the water actually lifts up the massive ice sheet and acts like grease, doubling the speed of the glaciers' journey over the bedrock to the sea. "It matters," says Richard Alley, professor of geosciences at Pennsylvania State University, and an ice-sheet expert: "It is not 'run for the hills, we are doomed,' but this tells us that loss of the Greenland ice could happen in centuries, not millennia."

[Dead_Parrot]

5. Because if you run for the hills....

...you'll just find yourself doomed up a hill. Much better to be doomed down in the valley where the good bars are.

:toast:

[Systematic Chaos]

6. Because The Powers That Be (tm) would be out of control in a nanosecond

if suddenly every newspaper, cable channel, town crier and pair of tin cans and string were broadcasting the news that every mile of coastline on the planet were subject to sudden drowning in a mile-high tidal wave? :shrug:

[pscot]

7. Makes one wonder what would happen

if an Atlantic hurricane worked its way up there, and rained out over the South Greenland ice cap. Imagine fifty or a hundred cubic miles of ice, floating like a rubber ducky.

[Shoelace]

10. annual ice loss is over 12 cubic miles per year!

and that's a conservative estimate from an article circa 2005 at the link.

http://www.earth-policy.org/Indicators/Ice/2005.htm


My question would be: how many cubic miles of ice melt (fresh water) pouring into the Arctic sea does it really take to shut down the Thermohaline circulation? Anybody have an educated guess?

Right around 12,900 +-, years ago at the start of the Younger Dryas, Lake Agassiz suddenly began draining into the St. Lawrence river to the Atlantic ocean (this might have been caused by a cometary impact as recent studies suggest). It was a huge thing, larger than the Caspian sea at one time in it's history. Could the melting of the Greenland ice cap, arctic sea ice be at all comparable to the Lake Agassiz event thus causing a similar shutdown and thousand year long cool period?
Plus, what if the other end of the ocean's circulation gets freshened by Antarctic ice melt at the same time? Is the day after tomorrow happening today?
:think: :shrug:


Damn, so many questions, so little time!






Glacial Lake Agassiz map
The map below shows the total area covered by Glacial Lake Agassiz over its entire history. It was never this large at any one time. This representation is based upon information in Minnesota's Geology (Ojakangas and Matsch, 1982).

[depakid]

8. Still one of scariest photo's ever:

[Shoelace]

9. 2nd scariest

other than looking at Condi Rice's eyes. Note the soot on the ice.


http://www.theage.com.au/ffximage/2007/11/14/B_ICE_wideweb__470x275,0.jpg

[Dead_Parrot]

11. No Shit. nt

[truebrit71]

12. That is NOT good...not good at all....

....