From the City College of New York: Extreme Melting on Greenland Ice Sheet, Reports CCNY Team
Glacial Melt Cycle Could Become Self-Amplifying, Making it Difficult to Halt
The Greenland ice sheet can experience extreme melting even when temperatures don’t hit record highs, according to a new analysis by Dr. Marco Tedesco, assistant professor in the Department of Earth and Atmospheric Sciences at The City College of New York. His findings suggest that glaciers could undergo a self-amplifying cycle of melting and warming that would be difficult to halt.
“We are finding that even if you don’t have record-breaking highs, as long as warm temperatures persist you can get record-breaking melting because of positive feedback mechanisms,” said Professor Tedesco, who directs CCNY’s Cryospheric Processes Laboratory and also serves on CUNY Graduate Center doctoral faculty.
Professor Tedesco and his team collected data for the analysis this past summer during a four-week expedition to the Jakobshavn Isbræ glacier in western Greenland. Their arrival preceded the onset of the melt season.
Combining data gathered on the ground with microwave satellite recordings and the output from a model of the ice sheet, he and graduate student Patrick Alexander found a near-record loss of snow and ice this year. The extensive melting continued even without last year’s record highs.
The team recorded data on air temperatures, wind speed, exposed ice and its movement, the emergence of streams and lakes of melt water on the surface, and the water’s eventual draining away beneath the glacier. This lost melt water can accelerate the ice sheet’s slide toward the sea where it calves new icebergs. Eventually, melt water reaches the ocean, contributing to the rising sea levels associated with long-term climate change.
The model showed that melting between June and August was well above the average for 1979 to 2010. In fact, melting in 2011 was the third most extensive since 1979, lagging behind only 2010 and 2007. The “mass balance”, or amount of snow gained minus the snow and ice that melted away, ended up tying last year’s record values.
Temperatures and an albedo feedback mechanism accounted for the record losses, Professor Tedesco explained. “Albedo” describes the amount of solar energy absorbed by the surface (e.g. snow, slush, or patches of exposed ice). A white blanket of snow reflects much of the sun’s energy and thus has a high albedo. Bare ice – being darker and absorbing more light and energy – has a lower albedo.
But absorbing more energy from the sun also means that darker patches warm up faster, just like the blacktop of a road in the summer. The more they warm, the faster they melt.
And a year that follows one with record high temperatures can have more dark ice just below the surface, ready to warm and melt as soon as temperatures begin to rise. This also explains why more ice sheet melting can occur even though temperatures did not break records.
Professor Tedesco likens the melting process to a speeding steam locomotive. Higher temperatures act like coal shoveled into the boiler, increasing the pace of melting. In this scenario, “lower albedo is a downhill slope,” he says. The darker surfaces collect more heat. In this situation, even without more coal shoveled into the boiler, as a train heads downhill, it gains speed. In other words, melting accelerates.
Only new falling snow puts the brakes on the process, covering the darker ice in a reflective blanket, Professor Tedesco says. The model showed that this year’s snowfall couldn’t compensate for melting in previous years. “The process never slowed down as much as it had in the past,” he explained. “The brakes engaged only every now and again.”
The team’s observations indicate that the process was not limited to the glacier they visited; it is a large-scale effect. “It’s a sign that not only do albedo and other variables play a role in acceleration of melting, but that this acceleration is happening in many places all over Greenland,” he cautioned. “We are currently trying to understand if this is a trend or will become one. This will help us to improve models projecting future melting scenarios and predict how they might evolve.”
Additional expedition team members included Christine Foreman of Montana State University, and Ian Willis and Alison Banwell of the Scott Polar Research Institute, Cambridge, UK.
Professor Tedesco and his team provide their preliminary results on the Cryospheric Processes Laboratory webpage. They will will be presenting further results at the American Geophysical Union Society (AGU) meeting in San Francisco on December 5 at 9 a.m. and December 6 at 11:35 a.m.
The research was supported by the National Science Foundation and the NASA Cryosphere Program. The World Wildlife Fund is acknowledged for supporting fieldwork activities.
On the Internet:
2011 Melting in Greenland report
http://greenland2011.cryocity.org
Cryospheric Processes Laboratory
Professor Tedesco Tracks Life and Death of Greenland Glacial Lake
http://www1.ccny.cuny.edu/advancement/news/Tedesco-Greenland-Glacial-Lake.cfm
Map of expedition location
Expedition Facebook page
http://www.facebook.com/pages/Cryocity/124269854300408
Expedition Twitter Feed
http://twitter.com/#!/Cryocity
Marco Tedesco profile
Your title is misleading Anthony. The melting occurs because melting in a previous year leads to a darkened surface, which then enables increase melting in the next year even without “record high temperatures.” As many other studies have shown, water seeping down through fissures to the bed rock below, is greatly accelerating the disintegration of the massive ice structures on Greenland. We would all be wise to fully understand these processes and the consequences which will occur as a result.(rising sea levels, desalinization of oceans, declining ocean currents)
That man in the photo looks more than a bit short of common sense. The Chunk of Ice he is stood on looks like it is about to break free at any moment.
The photographer who can see all the cracks and fissures below him was obiously not a good friend.
Hugh Pepper says:
“We would all be wise to fully understand these processes and the consequences which will occur as a result.(rising sea levels, desalinization of oceans, declining ocean currents)”
Thanx for your fantastic and incredible opinion. The fact that sea level rise is rapidly slowing, and the fact that oceans are not “desalinizing”, and the fact that ocean currents are not “declining” indicates that your lack of understanding of the issue is based on ridiculous, unscientific twaddle. Where do you find those provably wrong assumptions? Or do you just make them up as you go along?
The headline states:
Extreme melting in Greenland – no high temperatures required
However, the article actually says:
“We are finding that even if you don’t have record-breaking highs, as long as warm temperatures persist you can get record-breaking melting because of positive feedback mechanisms.”
and
“And a year that follows one with record high temperatures can have more dark ice just below the surface, ready to warm and melt as soon as temperatures begin to rise. “
So in fact, high temperatures ARE needed, both in the current year AND in the previous year to see the effect the article is talking about.
Hugh – Anthony picks the article, not the title. Perhaps a complaint to the authors on the offered link would be more constructive…
If I were Marco Tedesco I wouldn’t be standing where he is in the photograph.
That big chunk of ice he is on is about ready to crack off and go down the moulin.
A positive feedback usually works in both ways; so even if one exists… the mechanism they mention introduces a hysteresis. If it works that way, we could already be well into the cooling, yet the minimum sea ice extent managed to go down nearly to 2007 levels, or if you believe Bremen Uni, lower. Of course, at a certain point the hysteresis is overcome and the ensuing refreezing will be much more rapid.
@Mike Bromley the Kurd
Your feelings are correct. It is the expectation of a natural from observations to a general case conclusion about how things work.
Here is an example that is as valid an explanation of ice issues as many we have seen in the MSM:
From “The Central Eskimo”, Franz Boas, 1888 (Eastern Arctic, Canada) reported in “The Arctic Sky, Inuit Astronomy, Star Lore and Legend” by John MacDonald
“A long time ago the ocean suddenly began to rise, until it covered the whole land. The water even rose to the top of the mountains and ice drifted over them. When the flood had subsided the ice stranded and ever since forms an ice cap on the top of the mountains. Many shellfish, fish, seals and whales were left high and dry and their shells and bones can be seen to this day.”
So now you know.
The lack of short term correlation between temperature and melting is not surprising. Most melting occurs at low elevations, where ice is thin and the ground is warmer. The ground below the thinner ice has been warming since the Little Ice Age. But ice is a very good insulator, and the mile thick ice is fairly immune to secular temperature variation. But it is also immune to the effects of current annual variation.
I predict that warming will increase snowfall, piling the ice sheet so deep that it will collapse under its own weight, creating a tidal wave that will flood all the great capitals of the world. This will reduce carbon consumption, leading to eventual cooling, and so must be treated as negative feedback. –AGF
Wouldn’t looking at stream and river runoff data from North American mountain snowpacks provide a vastly better dataset? Throughout the Rockies we do record detailed weather information and water flow measurements, or wouldn’t that provide a cool enough field trip?
Meanwhile my models of Pacific plate tectonics show that a new continent formed between Hawaii and California last August. I’ve been trying to contact the business and government so they’ll know they can build a new harbor and new airport on it and make Pacific travel somewhat easier, but for some reason nobody e-mails me back. It’s a real head scratcher, as my model is quite specific abuot the location and size of the new lands. Perhaps I just need to give the place a catchier name than RUN01A7C or Modelerica.
So I’m a bit confused doesn’t the whole argument they present basically say
“It only take a very very small natural temp change to cause large scale melting and thus large scale melting is not proof of global warming”…
It least thats how i read the piece…
Hugh Pepper says:
October 26, 2011 at 9:27 am
“As many other studies have shown, water seeping down through fissures to the bed rock below, is greatly accelerating the disintegration of the massive ice structures on Greenland. We would all be wise to fully understand these processes and the consequences which will occur as a result.”
We would be even wiser to understand the processes and consequences of normal “behavior” of the Greenland ice sheet. The melting and seeping through the fissures IS part of the normal process. The other part is the formation of new ice every year. Some years, there is more new ice formed than melted. Some years there is less. Sometimes, those swings in increase or loss of ice span several years or even decades. This has been known for a long time. That’s the way I learned it in grade school decades ago. Still applies today. I love when “studies” like this are done and they really only show what is already known (or at least should have been known), yet think they’ve made some great discovery.
I won’t even get into how poor a study is that bases assumptions of future warming on such a limited time frame as satellites can provide for us and then compounds that with the use of MODELS. It is not sound science, no matter how “sciency” the wording of the results may sound.
By the way, here are a few known (and well documented) problems for the concept of unprecedented melting and/or melting rates and the massive global catastrophe they will supposedly unleash:
– The Vikings lived there when there was considerably less ice. They left only when the ice grew too much again for there continued use of the land. Now, the ice is supposedly losing some mass. Sounds cyclic to me and nothing in this “study” shows that the current period is not just on the warm end of a cycle.
– Planes that landed on the ice decades ago and were only recently found again were buried under over 200 feet of new ice that formed in the 60 years after they were abandoned.
-Based on estimates of the total volume of ice on Greenland and the currently accepted rate of melting, even if there was no new ice forming during the cold part of the year, it would take thousands of years for all the ice to melt.
Increasing melt rate of Greenland’s ice sheet = absolute catastrophe for the entire globe? Hmmm, what’s the word I’m looking for? Oh, yeah, FAIL!
Every time I see the phrase “positive feedback” in a climate paper, it is always misapplied and completely misunderstood.
The paper is wrong. The authors are idiots. Highly qualified in idiocy.
So a series of years with raised (but not continuously record-breaking) temperatures will allow melt to accelerate? I can buy that.
In which case, could a series of raised (but not continuously record-breaking) solar cycles allow temperature increase to continue and even accelerate? The Team would say No in the most strenuous terms. The analogy of the saucepan on the stove comes to mind…
I agree with jack mosevich: this is of very doubtful credibility in the absence of any sign of an acceleration in the rate of rise of sea levels.
Wouldn’t melting result in evaporation which results in cooling?
There might be a clue as to why the paper’s ‘findings’ are as they are. The last line in their statement to the press (here:- http://www.sciencedaily.com/releases/2011/10/111025163128.htm) is as follows ….
“The research was supported by the National Science Foundation and the NASA Cryosphere Program. The World Wildlife Fund is acknowledged for supporting fieldwork activities.”
“The model showed that melting between June and August was well above the average for 1979 to 2010”
Surely in mathmatical terms alone it is kind of important to have some values above the average. To not have any would mean your average was in fact your maximum.
Whenever we get a post on one of these hyperbolic PRs about Greenland “melting” I like to post a link to this site
http://tinyurl.com/yrdkl6
It’s an interactive map of global drought conditions from The Drought Monitor at UCL in the UK. heir timescales only go back 36 months, but I’ve been checking the site for almost 2 years and can attest that for almost 5 years the prevailing condition for Greenland has been for at least half of the island, and usually more, to be shown as experiencing severe to exceptional drought. In all that time I have only come across one of these opuses that even mentioned lack of replenishment as a possible contributor to whatever catastrophic ice loss they were pimping, and that mention was mostly an oh by the way aside.
It sounds like the high level of melt was more closely related to low levels of snowfall the preceding winter than to any alleged “Self-Amplifying Feedback” They even hinted at this when they said that 2011 was tied for the highest “mass balance” even though it was only the third highest summer melt. So so the little snow from winter 2010/2011 quickly melts, then the exposed ice, having higher albedo, melts faster. Simple enough. But a headline like “Low Snowfall Increases Loss Of Greenland Ice” doesn’t really sound that startling. More along the lines of obvious.
Crispin in Waterloo says:
October 26, 2011 at 8:39 am
“The conclusions are reasonable: melting cycles can be self-accelerating, and probably just as self-decelerating once the conditions are right. It seems quite possible that the whole island could melt eventually, in the sense that it is no longer covered by a permanant ice sheet, even if it continues to have hard winters.”
You mean “plausible” not “reasonable.” One could imagine this happening, so it is plausible. For it to be reasonable, there would need be some reasonably well-confirmed hypothesis that explains it. They offered none. Models are neither evidence nor reasonably well-confirmed hypotheses.
“This work advances our understanding of how ice sheets behave, at least some of the time.”
You mean it advances our understanding of something that we can imagine happening.
Understanding and Imagination are different faculties.
Dave Wendt says:
October 26, 2011 at 11:32 am
Whenever we get a post on one of these hyperbolic PRs about Greenland “melting” I like to post a link to this site.
Thank you for that link.
@Theo
Yes, I agree with you. Given the past behaviour, it is plausible. I am not sure I need to posit a hypothesis as to how it happens though I am sure people will. It is sufficient for me to know that it melted before and that it might be melting again and that we really do not know much other than change is constant.
“Professor Tedesco likens the melting process to a speeding steam locomotive. Higher temperatures act like coal shoveled into the boiler, increasing the pace of melting.”
I hope he knows a bit more about glacier melting than he does about steam locomotives, the coal usually goes in the firebox which heats and boils the water in the boiler to produce steam to drive the pistons and turn the wheels.
Coulda, woulda, shoulda; and here I thought the ice was actually melting.
Do these jerks never get tired of writing horror stories that would become true; if their science fiction were to become observed scientific fact.
So wake me, when the Greenland ice gets down to half its current total mass; or if the sea level gets up to the front steps of CCNY.
In the meantime; snore !!