11.6 billion gallon lake drains away in 90 min.!

[ensho]

http://hisz.rsoe.hu/alertmap/index.php?smp=&lang=eng


A vast lake containing 11.6billion gallons of meltwater has drained from the top of the Greenland ice sheet to its base in only 90 minutes, at a rate faster than that of Niagara Falls. Observations of the event in July 2006 have provided fresh insights into the dynamics of Greenland's land ice, which would add 7 metres (23ft) to global sea levels if it were to melt completely under the impact of global warming. The research reveals a “plumbing system” for the ice sheet, by which meltwater can force its way through up to a kilometre of ice to the underlying bedrock. While the rapid drainage of the meltwater was dramatic, analysis has indicated that such events appear to have less impact on the stability of the ice sheet than some scientists had feared. Every summer, meltwater accumulates on the surface of the Greenland ice sheet in huge lakes and some of this water sinks underneath the ice to reach the bedrock. This water provides a layer of lubrication, which has been suggested as an important factor in the accelerating advance of inland glaciers towards the sea. The process has raised concern that global warming could trigger a feedback effect that could speed up the disintegration of Greenland's ice. As rising temperatures melt more surface water in summer, greater quantities are expected to flow to the bedrock. This could lubricate ice flow still further, increasing the rate at which glaciers discharge into the sea.

The new research, led by Ian Joughin, of the University of Washington, and Sarah Das, of the Woods Hole Oceanographic Institution, suggests that while this process is important, it will not increase ice flow as much as had been feared. “The new findings indicate that while surface melt plays a substantial role in ice sheet dynamics, it may not produce large instabilities leading to sea level rise,” Dr Joughin said. Richard Alley, Professor of Geosciences at Pennsylvania State University, commented on the research: “What Joughin, Das and their co-authors confirm is that iceflow speed-up with meltwater is a widespread occurrence, not restricted to the one site where previously observed. “But, they also show that the really fast-moving ice doesn't speed up very much with this. So we can expect the ice sheet in a warming world to shrink somewhat faster than previously expected, but this mechanism will not cause greatly faster shrinkage.” In the study, which is published in the journal Science, the researchers document the fate of a lake of meltwater that formed and disappeared in July 2006. It once covered 5.6sq km (2.2sq miles), and emptied from the bottom in 24 hours, with most of the water draining in just 90 minutes. The scientists said that they were relieved not to have been on the lake in their 10ft boat at the time - and they now plan to deploy instruments only when surface lakes are dry. “We found clear evidence that supraglacial lakes - the pools of meltwater that form on the surface in summer - can actually drive a crack through the ice sheet in a process called hydrofracture,” Dr Das said. “If there is a crack or defect in the surface that is large enough, and a sufficient reservoir of water to keep that crack filled, it can create a conduit all the way down to the bed of the ice sheet.” )
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Ian doesn't really know.

the other day I posted where a glacier's melted water made a tunnel through the ice and exploded out the bottom into a river with such force it made the river run backwards for a time.

we all are rushing into the unknown

[BoneDaddy]

1. Jaysus

that is amazingly scary.

[ORDagnabbit]

2. heres an exact idea of how big that is...

Canadice
“Long Lake” Area 649 acres Length 3 miles Shoreline 7.2 miles Max. Depth 95 feet Max. Width 0.3 mile Volume 11.6 billion gallons Elevation 1096 feet Largest town Canadice Characteristics The highest in elevation, yet the smallest of the Finger Lakes. Boats may not exceed 16 feet in length and motors may not exceed 10 horsepower. Access to the lake is by permit only. It is one of the sources of water for the City of Rochester.


http://www.fingerlakes.org/nature/nature_lakes.htm

[ensho]

3. cripe - thank you for the stats

nt

[Systematic Chaos]

4. This needs to be posted in Environment/Energy as well.

But a :kick: from me for this one too. :)

[L. Coyote]

5. Try to imagine the discharge of Lake Missoula during the Pleistocene.

500 cubic miles of water rushing to the Pacific Ocean in a massive flood at regular intervals (on geological scale)!!

Missoula, Montana, has been under a deep lake many times. The drainage runs far north, into Canada, and returns south to the Oregon border in east Washington. A glacier blocks the channel up north, and the lake builds until it overcomes the ice wall. A lake extending across the state empties all at once!

Western Washington has a region known as the Scablands, where the flood swept across a plain. The Willamette Valley in Oregon filled with water, and overflowed the Coast Range at the south end. Early settlers thought Indians must have carried the huge erratic, igneous boulders from the Rocky Mountains. They were carried in chunks of glaciers.

=====================
Glacial Lake Missoula and the Ice Age Floods - http://www.glaciallakemissoula.org/story.html
The Channeled Scablands. The floodwaters from Glacial Lake Missoula moved through eastern Washington forever changing the landscape ...

A Geologic Catastrophy

Throughout the earth's history the climate has fluctuated and at times the temperatures have been cooler than they are now. This change in temperature can last somewhere between 2-10 million years and is referred to as an ice age.... at least five major ice ages in the past one billion years. The most recent, the Pleistocene Ice Age, began about 2 million years ago

........ a finger from the glacial ice sheet moved south through the Purcell Trench in northern Idaho, near present day Lake Pend Oreille, damming the Clark Fork River creating Glacial Lake Missoula.

The water began to build up behind the 2,500-foot ice dam ... creating a glacial lake the size of Lake Erie and Lake Ontario combined. The water continued to rise until it reached its maximum height at an elevation of 4,200 feet ... failure occurred when the water reached a depth of 2000 feet

..... estimated that the maximum rate of flow was equal to 9.46 cubic miles per hour (386 million cubic feet per second). This rate is 60 times the flow of the Amazon River ... drained in a few days to a week ... moving at speeds between 30 and 50 miles per hour raced across eastern Washington... from Glacial Lake Missoula moved through eastern Washington on a 430-mile journey to the Pacific Ocean ....

[L. Coyote]

6. The extent of the flood in this image

A Virtual Tour - http://www.glaciallakemissoula.org/virtualtour/scablands.html

The impact from Glacial Lake Missoula and the Missoula floods can be seen in parts of Montana, Idaho, Washington, and Oregon. Testifying to the cataclysm are the ancient shorelines, ripple marks, scoured lakes, dry channels, falls, and flood debris that are still visible after nearly 12,000 years. Without seeing this evidence it is hard to imagine the enormity of the geologic event.