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Like Butter: Study Explains Surprising Acceleration Of Greenland’s Inland Ice

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"Like Butter: Study Explains Surprising Acceleration Of Greenland’s Inland Ice"

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Meltwater from the surface of the Sermeq Avannarleq Glacier drains down toward interior ice. This photograph depicts a region about 10 miles from the ice sheet margin in Southwest Greenland. A new CIRES-led study helps explain the surprising acceleration of inland ice. Meltwater draining through the ice likely warms the ice sheet from the inside and like a stick of warm butter, the sheet softens, deforms and can flow faster. Photo: CIRES

In 2011, scientists explained that the Greenland Ice Sheet “could undergo a self-amplifying cycle of melting and warming” that is “difficult to halt.”

Last November, a major international study in the journal Science found that the Greenland ice sheet’s melt rate was up nearly 5-fold since the mid-1990s.

This acceleration has put ice sheet loss far ahead of what most climate models had predicted several years ago. Now a new study by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) in the Journal of Geophysical Research: Earth Surface explains at least one key factor the models have missed:

Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster.

The study notes that not only has the Greenland ice sheet accelerated at the edges where they flow into the ocean, but the “interior regions are also flowing much faster than they were in the winter of 2000-2001.”

To shed light on the observed acceleration, [Lead author Thomas] Phillips and his team developed a new model to investigate the effects of meltwater on the ice sheet’s physical properties. The team found that meltwater warms the ice sheet, which then—like a warm stick of butter—softens, deforms, and flows faster.

Previous studies estimated that it would take centuries to millennia for new climates to increase the temperature deep within ice sheets. But when the influence of meltwater is considered, warming can occur within decades and, thus, produce rapid accelerations.

Coauthor William Colgan explained, “The model shows that a slight warming of the ice near the ice sheet bed—only a couple of degrees Celsius—is sufficient to explain the widespread acceleration.”

The findings have important ramifications for ice sheets and glaciers everywhere. “It could imply that ice sheets can discharge ice into the ocean far more rapidly than currently estimated,” Phillips said. “It also means that the glaciers are not finished accelerating and may continue to accelerate for a while. As the area experiencing melt expands inland, the acceleration may be observed farther inland.”

This new study only serves to underscore a 2012 study that found we may be close to the Greenland Ice Sheet’s “tipping point.” The time to act is now!

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22 Responses to Like Butter: Study Explains Surprising Acceleration Of Greenland’s Inland Ice

  1. Joan Savage says:

    Thanks very much for this overview.

    Like many people, I live in a formerly glaciated environment. The landscape is full of evidence of enormous movements of glacial melt water that carved deep into ice and bedrock, and moved vast quantities of rock debris with the water.

    What don’t we understand about how we are pushing the system as much as 10,000x faster than in the previous de-glaciation?

  2. David Lewis says:

    Richard Alley gave a presentation at the recent AGU Chapman conference on Climate Science Communication (available here). He was more worried about parts of Antarctica, as he feels the Greenland ice sheet can’t just slide rapidly into the sea due to the fact it is sitting on “gnarly” rock.

    It would be interesting to hear his comments on this new study.

  3. Sasparilla says:

    Great analysis Joe, thank you.

  4. Robert in New Orleans says:

    So is the Greenland Ice sheet less stable then what we thought? Or perhaps the perceived stability was an illusion that we all bought into? Another unknown unknown?

    Given this information plus what is happening at the Pine Island Glacier in Antarctica do we see a one foot rise in sea level within the next twenty years?
    How about

    • John McCormick says:

      Robert, you answered each of your questions…answer is ‘yes’

    • Colorado Bob says:

      Speaking of known unknowns ……….. This little article has really struck me :

      “Peter Kershaw, adjunct professor in the earth sciences department at the University of Alberta, who was in Churchill recently on a research project, agrees. “It’s a big concern and so far not well-quantified,” said Kershaw, of greenhouse-gas emissions from thawing peat. “That organic material is being made available for decomposition. It’s out of the freezer and sitting on the counter.”

      One Kershaw study showed permafrost 15 metres deep in the Hudson Bay Lowlands has warmed by half a degree, from -0.9 degrees Celsius in the mid-1970s, to -0.45 degrees today. That half-degree warming penetrating so deeply into the ground is significant, he said.

      http://www.brandonsun.com/breaking-news/warmer-temps-threaten-railway-215197711.html?thx=y

      • Joan Savage says:

        Thanks for mentioning the 1970s.

        In the late 1980s, one of my graduate advisers met scientists working on permafrost who had already detected subtle temperature changes in Arctic soils. Their insight: by the time the politicians realize this is serious, it will be too late for many. How true their prediction.

    • BBHY says:

      Sometime in the next 20 years I believe we could see the West Antarctic Ice Sheet break loose, causing a very sudden, (under one year), 2 meter rise in sea level.

      • Jacob says:

        Maybe that’s what it will take for our government to spring into action?

        • If there is a sudden two meter rise in sea level, “our government” will be under water…at least D.C. will. Perhaps the government could relocate to the Rocky Mountains.

          NO! Wait! The Rockies are burning up. How about the great plains?

          NO! Wait! The great plains are turning into a dust bowl.

          Wow! I guess global warming really is global.

          (Maybe our government will just dissolve.)

          • Joan Savage says:

            Allegedly, a Cold War solution to the risk of nuclear war (another abrupt event to consider, to be sure) was to move the core personnel of government to an undisclosed location in the Appalachians. That approach was without thinking through the logistics of finding and moving people within the twenty minutes’ warning window for incoming missiles.

            A rush of meltwater from the Antarctic or Greenland might have weeks, months, or years to work its way to DC, but its disruption of climate along the way would be just as spectacular. Who needs science fiction.

          • Mulga Mumblebrain says:

            Joan, I just re-read The Black Cloud by Fred Hoyle, and his descriptions of the climate disturbances brought on by the cloud’s presence had a rather more chilling impact on me than they did decades ago.

    • Barry says:

      “So is the Greenland Ice sheet less stable then what we thought? Or perhaps the perceived stability was an illusion that we all bought into? Another unknown unknown?”

      From what I’ve gathered, the models are limited by the fact that if something is not proven it’s implicitly zeroed-out. If the acceleration in glacial melting wasn’t proven, then it wasn’t there. Also, the pattern I gather from the past few decades is that the previously-assumed negative feedback loops are failing.

      This leaves us in a situation where the negative feedbacks are failing, and new positive feedbacks are emerging.

  5. rollin says:

    Glaciers already have two factors that increase melt at the base, large pressures and heat transfer from the earth. When “warm” water is added, it makes sense that the ice at the base might melt and increase the slide toward the ocean.

  6. perceptiventity says:

    Does anybody know how many meters of sea level rise can the Thames Barrier flood defence withstand on top of a regular storm surge. I mean it was a bad idea to invest in the city of london real estate, wasit.

  7. Spike says:

    Hansen has previously argued that change may not be linear, but possibly exponential.

    http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf

    The paleo history is perhaps a clue – the last deglaciation (21 to 7 thousand years ago) was punctuated by several abrupt meltwater pulses. Around 14 thousand years ago, meltwater pulse 1A (MWP-1A), the largest of these events, produced a sea level rise of 14–18 metres over 350 years.

    http://www.paleo.bris.ac.uk/~ggxlg/deglac.html

    • Merrelyn Emery says:

      Spike, Hansen appears to be the only American climate scientist who has an inkling that the Earth is a system. He is beginning to understand why all the predictions have been way under, Lovelock understood it well, ME

  8. John McCormick says:

    Spike, many thanks for the link to the paleo record research of Dr. Lauren Gregoire
    School of geographical Sciences
    University of Bristol and her colleagues.

    Yes, “The paleo history is perhaps a clue” and given how we are traveling at light speed towards 2 then 3 then 4 degrees C increase in this century, the paleo history is the sentence being handed down upon our children and grandchildren.

  9. Daniel Coffey says:

    I wrote a column entitled “ices, ices, all fall down” December 16, 2010 pointing out the instability created by gravitational and pressure-drilling hydrostatic effects at transferring water within the ice structures and weakening the overall structural integrity. While internal heat transfer is interesting, the effect of gravitational deformation is what will really drive the rapid disintegration process.

  10. Chris Winter says:

    Reading this, I had the thought that this “Jokulhlaup” is something that could be modeled fairly easily. I don’t mean modeled by computer simulations, but by an actual physical model constructed at small scale inside a cold room.

    The only scientific problem might be the fact that the model’s “microglaciers” aren’t formed like natural glaciers by snow accumulation over thousands of years, hence differ in composition. But the mechanism of acceleration should still be demonstrable.