From the University of Colorado at Boulder Water flowing through ice sheets accelerates warming, could speed up ice flow
Caption: Standing melt water in Greenland crevasses can carry warmth to the ice sheet’s interior, accelerating the thermal response of the ice sheet to climate change.
Credit: Image courtesy Konrad Steffen, CIRES
Melt water flowing through ice sheets via crevasses, fractures and large drains called moulins can carry warmth into ice sheet interiors, greatly accelerating the thermal response of an ice sheet to climate change, according to a new study involving the University of Colorado at Boulder.
The new study showed ice sheets like the Greenland Ice Sheet can respond to such warming on the order of decades rather than the centuries projected by conventional thermal models. Ice flows more readily as it warms, so a warming climate can increase ice flows on ice sheets much faster than previously thought, said the study authors.
“We are finding that once such water flow is initiated through a new section of ice sheet, it can warm rather significantly and quickly, sometimes in just 10 years, ” said lead author Thomas Phillips, a research scientist with Cooperative Institute for Research in Environmental Sciences. CIRES is a joint institute between CU-Boulder and the National Oceanic and Atmospheric Administration.
Phillips, along with CU-Boulder civil, environmental and architectural engineering Professor Harihar Rajaram and CIRES Director Konrad Steffen described their results in a paper published online this week in Geophysical Research Letters.
Conventional thermal models of ice sheets do not factor in the presence of water within the ice sheet as a warming agent, but instead use models that primarily consider ice-sheet heating by warmer air on the ice sheet surface. In water’s absence, ice warms slowly in response to the increased surface temperatures from climate change, often requiring centuries to millennia to happen.
But the Greenland ice sheet is not one solid, smooth mass of ice. As the ice flows towards the coast, grating on bedrock, crevasses and new fractures form in the upper 100 feet of the ice sheet. Melt water flowing through these openings can create “ice caves” and networks of “pipes” that can carry water through the ice and spreading warmth, the authors concluded.
To quantify the influence of melt water, the scientists modeled what would happen to the ice sheet temperature if water flowed through it for eight weeks every summer — about the length of the active melt season. The result was a significantly faster-than-expected increase in ice sheet warming, which could take place on the order of years to decades depending on the spacing of crevasses and other “pipes” that bring warmer water into the ice sheet in summer.
“The key difference between our model and previous models is that we include heat exchange between water flowing through the ice sheet and the ice,” said Rajaram.
Several factors contributed to the warming and resulting acceleration of ice flow, including the fact that flowing water into the ice sheets can stay in liquid form even through the winter, slowing seasonal cooling. In addition, warmer ice sheets are more susceptible to increases of water flow, including the basal lubrication of ice that allows ice to flow more readily on bedrock.
A third factor is melt water cascading downward into the ice, which warms the surrounding ice. In this process the water can refreeze, creating additional cracks in the more vulnerable warm ice, according to the study.
Taken together, the interactions between water, temperature, and ice velocity spell even more rapid changes to ice sheets in a changing climate than currently anticipated, the authors concluded. After comparing observed temperature profiles from Greenland with the new model described in the paper, the authors concluded the observations were unexplainable unless they accounted for warming.
“The fact that the ice temperatures warm rather quickly is really the key piece that’s been overlooked in models currently being used to determine how Greenland responds to climate warming,” Steffen said. “However, this process is not the ‘death knell’ for the ice sheet. Even under such conditions, it would still take thousands of years for the Greenland ice sheet to disappear, Steffen said.
This study was funded by NASA’s Cryosphere Science Program.
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“”But the Greenland ice sheet is not one solid, smooth mass of ice. As the ice flows towards the coast, grating on bedrock, crevasses and new fractures form in the upper 100 feet of the ice sheet. Melt water flowing through these openings can create “ice caves” and networks of “pipes” that can carry water through the ice and spreading warmth, the authors concluded.””
So what value then is the Greenland Ice Core Data?
Ok, I’ve got to admit, I’m scratching my head over here. You mean, these brilliant scientists who’ve been studying all these melting glaciers for so many years, warning of how AGW is affecting them. Observing them. Describing in peer reviewed papers about moraines, moulins, crevassas, fractures, water flow within and beneath the ice, rivers in the ice, and on and on….
You mean to tell me they never considered a major and rather obvious part of the basic thermodynamics of the hydrological cycles involved? That all the models were…. gasp…. wrong???!! Sigh.
So… what else, what other natural cycles and physical functions haven’t they considered that’s staring them right in the face – either wrt to glaciers & ice caps, or the larger global warming models?
But we’re supposed to trust the accuracy of predictions and conclusions based on these various models? The science is incontrovertible and undebatable, the scientists all in utter consensus.
Call me skeptical (pun intended).
This may be an excellent model. Only one question. Where is the heat that melts the water in the first place coming from? From friction below? but that must always be the case: the method of distribution can hardly make any difference. It must always reach up through the ice. And there is only so much of it.
From above perhaps? how exactly? No energy input means no heat, no heat means no melting, so how meltwater might distribute this notional but non existent heat is merely an academic exercise in futility well suited to computer modelling.
Kindest Regards
Cobblers
To quantify the influence of melt water, the scientists modeled…blah blah blah… depending on the spacing of crevasses and other “pipes” that bring warmer water into the ice sheet in summer.>>
Nothing in here about actually going out to the ice sheet and doing any kind of survey to quantify the actual size and spacing. They then run a whole bunch of different scenarios. Then they compare to the temperature record and conclude that it matches their model better than all the others so they must be right. Well with so many scenarios based entirely on conjecture I’m sure at least one of them did, which says nothing for it being right or not. When they can match their model output to actual measured physical characteristics of the ice, then they can shoot their mouths off.
Interesting little caveat they insert at the very end. Yes our model is better and yes it shows that ice sheets might melt even faster than anyone thought before…. oh but it will still take thousands of years.
So, the previous models assumed that the ice didn’t melt, but evaporated? That’s some warming!
Where is the physical validation of computer models?
“The fact that the ice temperatures warm rather quickly is really the key piece that’s been overlooked in models currently being used…”
Why, a model without distortion is like champagne without fizz, like steak without sizzle, or a rose with no scent. One might say, the distortion IS the model.
“The fact that the ice temperatures warm rather quickly is really the key piece that’s been overlooked in models currently being used to determine how Greenland responds to climate warming,” Steffen said.
So essentially the crazies at NASA overlooked something that has been known for “ever” by not just the locals living near or on any great body of ice but even by high school kids in the entire western world who are learning this basic stuff at a young age.
And people still wonder why NASA hasn’t put a man on the moon again for so long.
Quoting from the article:
“The key difference between our model and previous models is that we include heat exchange between water flowing through the ice sheet and the ice,” said Rajaram.
I also saw a lot of if-could-might-possibly in the article based on this new and improved model, but what is the ice sheet actually doing?
If my granny had wheels, she’d be a wagon.
I love the way “circulation” is included when it helps support the theory of “doomsday warming”, but when it doesn’t as in the fact that warm air rises, that it takes heat from the surface and then the increased CO2 helps irradiate that heat …. it is totally ignored!
Indeed we even get statements to the effect … CO2 is a warming gas … when it is also according to basic science … a cooling gas.
It’s a bit like painting a surface black … it is warmer in the day …but cooler at night. CO2 helps trap IR near the surface and it helps cool via higher IR emissions at higher levels when you have the warm air that has risen up exposed through a thin atmosphere to the super-cold of space.
There is absolutely nothing new in this. Temperate ice sheets (like Greenland) have always been like this. This has been well understood since the dawn of glaciology. A E Nordenskiöld, the first scientist ever to get up on the Greenland ice made an excellent and graphic description of crevasses, superglacial lakes and rivers, moulins and subglacial rivers back in 1880.
While this might not be factored into glacier modelling (which, if true, indicates rather remarkable ignorance and/or incompetence) it has certainly been at work in the melting of ice sheets in the past. These ice sheets have never shown any signs of any superfast melting/movement, so the new shiny models are probably no better than the old ones.
The spectacle of ‘scientists’ constantly generating ‘studies’ after developing ‘better’ models on their Xboxes without doing the hard, outdoor observational stuff is truly sad. Years ago a young and very bright scientist admitted to me that ‘science is about 90% stamp-collecting in uncomfortable and inconvenient places’ – what happenned to that model of scientist?
How much warming is Greenland actually experiencing?
I had thought that Greenland’s temps were much higher during the Holocene Climate Optimum than they are now. Somehow it lasted through several thousand years of higher temps, but it’s going to be ravaged by a few decades of lower temps? How exactly does that happen?
Warm water melts ice!!!!
More funding please.
I should`ve been a scientist.
Things are changing though, a year ago the bbc would have led with this.
RE: conradg says:
November 5, 2010 at 2:23 am
How much warming is Greenland actually experiencing?
Greenland….
http://i247.photobucket.com/albums/gg136/BigLee57/Global%20Warming/GLTassilaq1.jpg
http://i247.photobucket.com/albums/gg136/BigLee57/Global%20Warming/GLNuuk1.jpg
http://i247.photobucket.com/albums/gg136/BigLee57/Global%20Warming/GLIllulisat1.jpg
http://i247.photobucket.com/albums/gg136/BigLee57/Global%20Warming/GLUpernavik1-1.jpg
Over in Russia for the heck of it…
http://i247.photobucket.com/albums/gg136/BigLee57/Global%20Warming/RuOstrov-1.png
http://i247.photobucket.com/albums/gg136/BigLee57/Global%20Warming/RuKandalaksa-1.png
Nice change of tone.
A year ago a good end phrase would have been:
“…so a warming climate can increase ice flows on ice sheets much faster than previously thought, said the study authors.” (Give us more money.)
Now the end is:
“However, this process is not the ‘death knell’ for the ice sheet. Even under such conditions, it would still take thousands of years for the Greenland ice sheet to disappear, Steffen said.”
May I take that to mean: “And please do not lump us together with the IPCC and their absurd prediction of Himalaya glaciers gone by 2035.”?
The skeptics’ consistent criticism of the warmists with good science is slowly but surely changing the scientific climate and bringing science back to the place it deserves – sort of like a glacier melting.
Go the Vibrance slider!!!
Then why are the ice sheets still there? The past was warmer than today in that region. The last 1,000 years have been the coldest since the Holocene began. How did it survive in the past if all of these “threats” are so dire….
http://theinconvenientskeptic.com/2010/11/holocene-cooling-trend/
John Kehr
Seriously, how dim are these people? It would seem to me that both grants and academic qualifications are being a bit too freely distributed in the Climate Studies Arena.
Still, at least they’re playing to their audience. It’s Melting and “It’s worse than we thought”
If there’s one thing that Ice never is, its static. It’s always changing, we should just all be grateful that we are living in an interglacial period – Ice not melting – Now, that would really, really, really be a problem.
Woods Hole Oceanographic Institute and University of Washington Scientists Chris Linder and Sarah Das having the time of their lives studying the melt-water lakes on the Greenland Icepack in 2008.
Nice video, but the object of their research appears to have been the documentation of what they thought was the impact of ‘climate change’ on the ice-pack.
OK, when the earth or that section is experiencing a warming cycle ice will fracture and heat will flow with the water thru fissures. Duh!! I could of told you that for a lot less. Why do you think the beer cools faster in a cooler with water and crushed ice?
And what does this have to do with AGW? The phenomenon occurs whether man made warming or natural!! How do I tap into this grant/study money?
It is known that glacial ice is not like ice cubes from your freezer, it is compacted layers of snowfall which at some point might have gotten slightly wet during the summer melt season. By normal mechanical forces the layers can also be cracked, fractured, with pieces mixed up somewhat.
So basically, the previous modeling was using igneous rock when they should have modeled sedimentary and perhaps metamorphic rock. And this was found to be surprising.
This reinforces my belief that (nearly?) all the sciences need to be torn down, dissected, and rebuilt into a unified form using common principles and especially a common language. For example, as I keep looking at the recent advances in vascular surgery, from stents to clot filters to ways to remove blockages and clean out accumulations, I’m certain we would have had those advances decades ago if medical researchers had studied plumbing.
Typical, keep changing the Model until you get the answer you want!
No worries then since current Greenland temperatures are lower than in the 1930’s!
“The key difference between our model and previous models is that we include heat exchange between water flowing through the ice sheet and the ice,” said Rajaram.
I stopped reading any further at that point.