From the University of Colorado at Boulder, worry over something that is a natural process that has happened for thousands of years. You gotta love this one: ” Catastrophic lake drainages were 3.5 times more likely to occur during the warmest years than the coldest years.”. Gee, ya think? Or how about this one: “Once the water reaches the ice sheet’s belly that abuts underlying rock, it may turn the ice-bed surface into a Slip ‘N Slide, lubricating the ice sheet’s glide into the ocean.”. Hmm well, the “may” weasel word says that they really don’t know. The Greenland ice sheet is up to 1.8 miles (3 kilometers.) thick in the middle, and that huge weight depresses the underlying crust, which assumes the concave shape of a saucer. So I guess I’m not too worried about it slip-sliding away. And as WUWT has covered before, the warming in Greenland has some issues.
CU-Boulder study shows Greenland may be slip-sliding away due to surface lake melt
Like snow sliding off a roof on a sunny day, the Greenland Ice Sheet may be sliding faster into the ocean due to massive releases of meltwater from surface lakes, according to a new study by the University of Colorado Boulder-based Cooperative Institute for Research in Environmental Sciences.
Such lake drainages may affect sea-level rise, with implications for coastal communities, according to the researchers. “This is the first evidence that Greenland’s ‘supraglacial’ lakes have responded to recent increases in surface meltwater production by draining more frequently, as opposed to growing in size,” says CIRES research associate William Colgan, who co-led the new study with CU-Boulder computer science doctoral student Yu-Li Liang.
During summer, meltwater pools into lakes on the ice sheet’s surface. When the water pressure gets high enough, the ice fractures beneath the lake, forming a vertical drainpipe, and “a huge burst of water quickly pulses through to the bed of the ice sheet,” Colgan said.
The study is being published online today by the journal Remote Sensing of the Environment. The study was funded by the Arctic Sciences Program of the National Science Foundation.
The researchers used satellite images along with innovative feature-recognition software to monitor nearly 1,000 lakes on a Connecticut-sized portion of the ice sheet over a 10-year period. They discovered that as the climate warms, such catastrophic lake drainages are increasing in frequency. Catastrophic lake drainages were 3.5 times more likely to occur during the warmest years than the coldest years.
During a typical catastrophic lake drainage, about 1 million cubic meters of meltwater — which is equivalent to the volume of about 4,000 Olympic swimming pools — funnels to the ice sheet’s underside within a day or two. Once the water reaches the ice sheet’s belly that abuts underlying rock, it may turn the ice-bed surface into a Slip ‘N Slide, lubricating the ice sheet’s glide into the ocean. This would accelerate the sea-level rise associated with climate change.
Alternatively, however, the lake drainages may carve out sub-glacial “sewers” to efficiently route water to the ocean. “This would drain the ice sheet’s water, making less water available for ice-sheet sliding,” Colgan said. That would slow the ice sheet’s migration into the ocean and decelerate sea-level rise.
“Lake drainages are a wild card in terms of whether they enhance or decrease the ice sheet’s slide,” Colgan said. Finding out which scenario is correct is a pressing question for climate models and for communities preparing for sea-level change, he said.
For the study, the researchers developed new feature-recognition software capable of identifying supraglacial lakes in satellite images and determining their size and when they appear and disappear. “Previously, much of this had to be double-checked manually,” Colgan said. “Now we feed the images into the code, and the program can recognize whether a feature is a lake or not, with high confidence and no manual intervention.”
Automating the process was vital since the study looked at more than 9,000 images. The researchers verified the program’s accuracy by manually looking at about 30 percent of the images over 30 percent of the study area. They found that the algorithm — a step-by-step procedure for calculations — correctly detected and tracked 99 percent of supraglacial lakes.
The program could be useful in future studies to determine how lake drainages affect sea-level rise, according to the researchers. CIRES co-authors on the team include Konrad Steffen, Waleed Abdalati, Julienne Stroeve and Nicolas Bayou.
###
Yes, it’s the perfect climate-science paper. Based on automated-scanning data and feature-recognition software (BUT, honest, we manually checked 30% of 30% of the observations!! soooooo boring), you conclude that “catastrophic” lake-drainage could:
1) Rapidly accelerate glacier flow to the ocean (slip-slidin’, ticklin’ the belly hypothesis), or
2) Seize-up glacial flow toward the ocean (sub-glacial sewer hypothesis).
Whatever happens, you’ve got it covered. And there’s no way to test either hypothesis
Is this great science, or what?!??
Next paper will use a model with “algorithms” to calculate the size of the tsunami when the ice cap catastrophically slides into the Atlantic. Bye, bye Florida!
As JL points out, the only way that sudden discharges of meltwater can spread laterally between the base of a glacier and its bed is if the water pressure becomes high enough to lift the glacier off its bed to allow the water to spread. That can happen locally in alpine glaciers where the ice is thin relative to water pressure and may speed up glacial motion. But the Greenland ice sheet is more than 10,000 feet thick. Think how much water pressure would be needed to lift that thickness of ice.
“During summer, meltwater pools into lakes on the ice sheet’s surface. When the water pressure gets high enough, the ice fractures beneath the lake, forming a vertical drainpipe, and “a huge burst of water quickly pulses through to the bed of the ice sheet,” Colgan said.”
Thery have, of course, calculated the pressure (i.e. weight) of the water on the ice surface and what weight is necessary to make a crack in the ice 1.8km deep………….No? I thought not!!
Good heavens, a kid at elementary school would get detention for writing rubbish like this!
Jim B in Canada says:
April 17, 2012 at 7:50 am
OFF TOPIC
There is yet another biased poll being used for political purposes here http://www.inews880.com/index.aspx
I was wondering if the WUWT crowd would come on and vote for sanity.”
I voted: Score at that time: Yes 23.4% No 76.6% I’ll come back in 2 hours and vote again!
Here’s something else to think about. The water/ice phase relationship is pressure dependent–you can melt ice which is below the freezing point by applying enough pressure. When Ice freezes, it increases in volume. If you apply enough pressure, the ice/water equilibrium relationship tends to revert to the phase with smaller volume (water). Ice in temperate glaciers is usually close to the pressure-melting point. Where basal meltwater exists under substantial ice thickness, it is generally below the atmospheric freezing point of water (0 degrees C; 32 degrees F). Research in Iceland and Alaska glaciers has shown that when such water is forced to rise upward to the surface under hydrostatic pressure, the water will refreeze onto the base of the glacier. I’ve seen this happening at the termini of Alaskan glaciers. If subglacial water at the base of the Greenland ice sheet were to rise up several hundred meters out of its basin, it would surely be supercooled and would freeze onto the base of the glacier.
4 eyes says:
April 17, 2012 at 3:10 am
Does anyone know the temperature at the interface of the rock and and the bottom of the ice sheet?
======
There are a couple of Greenland hot springs in the area of the Southern tip and mid Western coastal areas but there is also this about other hotspots.
Byrd Polar Research Center
at Ohio State University
2007
OSU Research News, December 7. Earth’s Heat Adds to Climate Change to Melt Greenland Ice. Article discusses Ralph von Frese‘s research into “hotspots” under Greendland which may be melting the ice above or enabling ice to slide more rapidly out to sea.
“COLUMBUS , Ohio — Scientists have discovered what they think may be another reason why Greenland ‘s ice is melting: a thin spot in Earth’s crust is enabling underground magma to heat the ice.”
“They have found at least one hotspot in the northeast corner of Greenland –just below a site where an ice stream was recently discovered.”
source: http://researchnews.osu.edu/archive/hotgreen.htm
John from CA says:
April 17, 2012 at 8:33 am
There are a couple of Greenland hot springs in the area of the Southern tip and mid Western coastal areas but there is also this about other hotspots.
s/b
There are a couple of Greenland hot springs in the area of the Southern tip and Eastern coastal area but there is also this about other hotspots.
I live in Iowa.
Somebody please alert me when Greenland has crossed the Canadian border.
I don’t want to be caught unprepared.
I can simplify this physical event for evaluation.
I suggest the following experiment:
Freeze 1 square foot of ice, 2 inches thick.
Drill 1/4 inch holes in the ice every 2 inches.
Also chill 2 quarts of water to 32 degrees F,
so that it starts to freeze.
Put 1/2 inch of sand on a card table.
Place the ice in the middle of the card table.
Pour 1 quart of water over the ice to fill all the holes with “high pressure water”.
Drink the other quart to stay properly hydrated during observation.
Watch it just sit there.
Keep watching until the ice melts.
I see no reasonable force presenting itself causing the ice to move.
The only way to get that ice to move would be to position a dike around the ice to capture enough melt water to “float” the ice off of the sand. Getting the ice close to floating would reduce the coefficient of friction enough so that the wind could move the ice, but the dike would keep it from falling off the table.
Suggesting the ice sheet will slip off Greenland is not logical.
Tilting Greenland to the same angle of a roof, could help the ice sheet “slip off” however one must consider imbalance and the “tipping over” of the whole Island as presented by Hank Johnson and the Island of Guam:
Maybe the above “Hank’s Phenomenon” is what they are referring to.
Massive flooding was a common occurrence 15,000 years ago from Lake Missoula when glacial ice would float when enough water dammed behind it releasing a torrent of water that flooded across Idaho and Eastern Washington. As climate warmed from 15,000 to 13,000 years the number of flooding from this glacial ice dam increased.
“Thousands of varves were deposited in Lake Missoula. At the best-known Ninemile locality near Missoula, about 40 rhythmites consist of varves overlain by a sand/silt layer [Figs. 61, 62]. The varves were deposited on the floor of Lake Missoula, and the sand/silt layers represent subaerial
exposure and deposition in a stream. The number of varves in each rhythmite varies from 9 to 40, decreasing regularly upward, and the total number of varves is just less than one thousand.
An interpretation of these data would suggest: [1] Lake Missoula filled and emptied [in a catastrophic flood] about 40 times, [2] it took 9 to 40 years to fill the lake, each successive lake requiring less time, and [3] the process was repeated over a period of about one thousand
years. Because Ninemile is about in the middle of the very long lake, the record here would not provide a complete history of the lake. Correlating Ninemile with the downstream record would suggest these events were in the latter half of the entire flood history.
http://geology.mines.edu/faculty/Klee/Missoula.pdf
Nothing new….
Funny how these authors basically sensationalize basic glacier physics…their olympic-sized swimming pools will have long frozen once they get below the ice.
Such bunk writing. Just another indication of the poor quality of professors allowing junk newspaper style research. A total waste of funding going into what we already know is that Greenland during warm periods is GREEN. Scary stuff.
If you look at the Google satellite view of Greenland, it appears that glaciers there in starting to surge. Seems like things are in or soon will be in a growth mode. The real worry is not reduction in the overall glacial mass there. The real worry would be, glaciers forming shelves into the Davis Strait. If a glacier jumps the Davis Strait, we are in a whole new (scary) mode.
Mike McMillan says:
April 17, 2012 at 3:56 am
“Much of the central axis of Greenland is 200 feet below sea level, with mountains around the periphery. With enou
gh warming before the next ice age, we may get Lake Greenland, but she’s not gonna slide nowhere.”
map –
http://i44.tinypic.com/r10nd0.jpg
The map shows topographic drainage toward central Greenland from both east and west coastlines. Any lake drainage would flow towards Greenland’s interior not the ocean.
What about Lake Vostok?
If “1 million cubic meters of meltwater” are something to worry about, then wouldn’t something the size of Lake Ontario (though much deeper) be a bigger issue?
1e6 m3 vs 5,400 km3 = 5.4e12 m3
And that is only one of about 140 lakes nuder the ice.
They did this about five years ago, with thousands of ducks. I think I saw an article in color on it in a science magazine. (I no longer subscribe to such.) Dunno if they came out.
Speaking of the North Arctic…
Looks like the Blue line is likely to “slip and slide” into the Gray line…
http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png
I hope it makes a loud noisy crunching colliding sound when it happens…
Charts could be more exciting with audio enhancements.
I’m surprised no one has posted this video yet:
HAL said:
“I live in Iowa.
Somebody please alert me when Greenland has crossed the Canadian border.
I don’t want to be caught unprepared.”
Brilliant!
Just to be on the safe side – pick up the phone to me in the UK and leave it connected. When it disconnects you’ll know it’s passed the UK.
Good luck everyone its worse than we thought.
“Here’s something else to think about. The water/ice phase relationship is pressure dependent–you can melt ice which is below the freezing point by applying enough pressure. When Ice freezes, it increases in volume. If you apply enough pressure, the ice/water equilibrium relationship tends to revert to the phase with smaller volume (water). ”
*****************
I believe that’s the principle behind ice skating. The weight of the skater on thin blades exerts a momentary strong pressure on the ice, which melts and allows the skater to glide forward. The momentarily-melted water re-freezes once the skater has moved on.
Catawicked, in my opinion.
If the study area is on the flank of the ice sheet where the ice is thin, I suppose you could get water flow out from the sheet but in itself is a false reference to the main ice sheet where the basal rock is depressed into a bathtub shape. So why is this not not discussed more even if it is not adequately explained by the researchers or the press? We would not want to give up too much info now would we. More facts only confuses the masses anyway.
“THEY” KEEP MOVING THE GOAL POSTS !!
Just above I posted this:
kbray in california says: April 17, 2012 at 10:56 am
Speaking of the North Arctic…
Looks like the Blue line is likely to “slip and slide” into the Gray line…
I noticed today that someone has adjusted the lines further apart….
Steve Goddard at Real Science shows what “they” did here:
http://www.Real-Science.com/breaking-news-nsidc-gets-in-the-data-tampering-act#comments
This is anthropogenic manipulation by a##holes.
Here is a better link to Steve’s post:
http://www.Real-Science.com/breaking-news-nsidc-gets-in-the-data-tampering-act
REPLY: Yeah its a processing glitch. I’ve been in touch with NSIDC and they are working to fix it…no nefarious motives there – Anthony
REPLY: Yeah its a processing glitch. I’ve been in touch with NSIDC and they are working to fix it…no nefarious motives there – Anthony
——————————————————————————–
Giving the benefit of the doubt….ok…
…but it does give one pause to wonder…
I have noticed “adjustments” more than once.
If I knew more about their process, it’s easier to be more forgiving.
I imagined that they were only processing a number, but it must be more involved than that.
Seeing “manipulation” over and over makes for a short fuse and a quickness to pounce.
Apologies are hereby presented.