Domino effect of chain reaction drainage of surface lakes led to the breakup of Larsen B Ice Shelf in 2002

No mention of “climate change” as the driver for the sudden event.

Larson Ice Shelf on February 21, 2000. Pools of melt water are visible on the surface of the Larsen Ice Shelf, and drifting icebergs split from the shelf are signs of approaching collapse. (Credit: Image courtesy Landsat 7 Science Team and NASA GSFC)

Larson Ice Shelf Pools of melt water are visible on the surface of the Larsen Ice Shelf, and drifting icebergs split from the shelf are signs of approaching collapse. (Credit: Image courtesy Landsat 7 Science Team and NASA GSFC)

When the Larsen B Ice Shelf in Antarctica collapsed in 2002, the event appeared to be a sudden response to climate change, and this long, fringing ice shelf in the north west part of the Weddell Sea was assumed to be the latest in a long line of victims of Antarctic summer heat waves linked to Global Warming. Back in 2008 a paper published in the Journal of Glaciology, Prof. Neil Glasser of Aberystwyth University, and Dr Ted Scambos of University of Colorado’s National Snow and Ice Data Center said that the shelf was already teetering on collapse before the final summer. “Ice shelf collapse is not as simple as we first thought,” said Professor Glasser, lead author of the paper. “Because large amounts of meltwater appeared on the ice shelf just before it collapsed, we had always assumed that air temperature increases were to blame. But our new study shows that ice-shelf break up is not controlled simply by climate.

Source: http://www.sciencedaily.com/releases/2008/02/080210100441.htm

Now they have a mechanism with this new paper just published in GRL:

Chain reaction drainage of supraglacial lakes led to breakup of Larsen B Ice Shelf

In 2002, Antarctica’s Larsen B Ice Shelf disintegrated over the course of just a few months. The shelf, which covered more than 3000 square kilometers (1158 square miles) of ice, had been stable for thousands of years before it broke up, and the processes involved in the sudden breakup were not well understood. Before the breakup, there were more than 2700 small supraglacial lakes on top of the ice shelf that had formed as ice melted gradually over the preceding years. Observations indicated that the majority of those lakes drained within the final few days before the ice shelf broke up, but scientists were not certain how that could have happened.

Now, using a simulation of the stresses that the lakes create on the ice shelf, Banwell et al. show that the draining of one supraglacial lake could result in fractures under other lakes, which, in turn, could cause more fractures under more lakes and thus cause numerous lakes to drain, in a chain reaction. The draining of many supraglacial lakes in a short time period ultimately led to the breakup of the entire ice shelf, the authors suggest.

Source: Geophysical Research Letters, doi:10.1002/2013GL057694, 2013 http://onlinelibrary.wiley.com/doi/10.1002/2013GL057694/abstract

Title: Breakup of the Larsen B Ice Shelf triggered by chain reaction drainage of supraglacial lakes

Authors: Alison F. Banwell: Department of Geophysical Sciences, University of Chicago, Chicago, Illinois, USA; and Scott Polar Research Institute, University of Cambridge, Cambridge, UK;

Douglas R. MacAyeal: Department of Geophysical Sciences, University of Chicago, Chicago, Illinois, USA;

Olga V. Sergienko: The Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, New Jersey, USA.

Abstract: The explosive disintegration of the Larsen B Ice Shelf poses two unresolved questions: What process (1) set a horizontal fracture spacing sufficiently small to predispose the subsequent ice shelf fragments to capsize and (2) synchronized the widespread drainage of >2750 supraglacial meltwater lakes observed in the days prior to break up? We answer both questions through analysis of the ice shelf’s elastic flexure response to the supraglacial lakes on the ice shelf prior to break up. By expanding the previously articulated role of lakes beyond mere water reservoirs supporting hydrofracture, we show that lake-induced flexural stresses produce a fracture network with appropriate horizontal spacing to induce capsize-driven breakup. The analysis of flexural stresses suggests that drainage of a single lake can cause neighboring lakes to drain, which, in turn, causes farther removed lakes to drain. Such self-stimulating behavior can account for the sudden, widespread appearance of a fracture system capable of driving explosive break up.

==============================================================

grl51129-fig-0003Figure at left:

Chain reaction drainage of supraglacial lakes. (a) Observed lakes [Glasser and Scambos, ] are represented by circular disks of equal area and constant depth (5 m). The lake found to trigger the drainage of most neighboring lakes is labeled “starter lake.” Colored surrounding lakes indicate those that are induced to drain either directly by the starter lake’s effect on flexure stresses (stage = 1) or indirectly by lakes which are drained at an earlier stage (stage = 2, …, 10). The color of the lake indicates its stage according to the color bar. When the fracture criterion of 70 kPa is evaluated at each lake’s center, a total of 227 lakes are triggered to drain by the starter lake (either directly or indirectly). The radii of colored lakes are drawn at twice the scale to promote visibility. The radii of gray‐shaded lakes, which are not drained as a result of the chain reaction, are drawn at true scale. (b) As in Figure a but with the fracture criterion reduced to 35 kPa.

About these ads

29 thoughts on “Domino effect of chain reaction drainage of surface lakes led to the breakup of Larsen B Ice Shelf in 2002

  1. Scenario A- The “global warming” going on caused the meltwater lakes, and as the warming increased, the water in those lakes evaporated in a catastrophically rapid manner, and made the ice dry and brittle and it just SHATTERED into dust…..
    Scenario B- The water in the meltwater lakes came to a boil, and tunneled down through the ice, causing a giant perforation line that then was too heavy to resist gravity and it fell in.
    Scenario C- In 2002, Chris Turney led an Australiasianantarctican expedition to the Larsen Ice Shelf area. One of the Argos on board got stuck, and in an effort to free it from the sea, he tied the Argo to the ship, and as they pulled back, the entire ice shelf came off with the freed Argo…neither Robbie, nor Janet was on that trip to rat them out, so they draped the ship in a white sheet of plastic and floated out of the area…kind of like the Millenium falcon did with Empire’s trash dump…

  2. Speaking as an uneducated peasant, could the breakup of the Larsen B Ice Shelf have anything to do with the 16 nunataks situated 8-9 kilometres to the north?

  3. Aphan says….
    >>>>>>>>>>>>>
    I vote for scenario C.

    Or D.

    The ice extended into the ocean so far and there wasn’t enough support for the amount of ice. Waves and tides and all that.

  4. Anthony: your No mention of “climate change” as the driver for the sudden event.

    You may want to correct this.

    From the Science Daily site

    Professor Glasser acknowledges that global warming had a major part to play in the collapse…

    That said, the article did go on to say:

    pointed to an ice shelf in distress for decades previously

    REPLY: that refers to the current paper, not the 2008 news article – Anthony

  5. In addition, at the time of the collapse, the stronger westerly winds blew over the peninsula instead of going around. This created a strong downward pressures as well as a foehn storm that was moist likely the cause of the melt ponds. If memory serves, that change in winds also altered the Weddell Sea gyre that pushed water and ice up against the ice shelf. The change in winds and pressure lowered sea levels locally , adding more stress to the shelf.

  6. If the surface lakes drained simultaneously, I’d expect it was because of fissuring due to shelf-wide slumping prior to the failure. The slumping would come from progressive failures of very large sub-surface crevasses which are typical of large ice formations — like ice caves.

  7. Seems easily forgotten that the Planet Earth has a long time line. Such things as glacial periods and interglacials. There has been some climate change in the last 17,000 years. But what I really hate are statements such as: “But our new study shows that ice-shelf break up is not controlled simply by climate.” Lazy writers!
    ~~~~~~

    And from Skeptik, the uneducated peasant, we have entered into the conversation the word nunatak, a frequently used term by park bench sitters, and squirrel hunters. Excellent.
    I have no answer to the question, although I can’t imagine why they would.

  8. Damn – I transcribed the dates into the wrong rows so sorry, no, it cannot have affected the event as the collapse was in Jan 2002. If I were a real climate scientist I’d probably just ignore that troubling fact.

  9. If sea levels are rising, however gradually, a thousand year ice shelf is under immense lifting pressure.

  10. Brian H says:
    January 8, 2014 at 6:09 pm~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    ‘We answer both questions through analysis of the ice shelf’s elastic flexure response ‘

    No problem see? :)

  11. The reason for surface lakes draining was known almost 100 years ago to happen and why. Well known reason. Winderosion and temperature erosion combined with two other major factors:

    * difference in density between surface and ice under.
    Same factors that were there when the latest Ice Age Ice withdraw from south to north (approx) in northern Hemisphere.

    * Earth angle to a certain point/area etc at the time prior to the time observed.

    If you take those factors as well as some of the other major well known factors of Antarctica, such as the large seas under ice and the difference between highest and lowest temperature under the short summerperiod in Antarctica, you will find that it’s allmost ends up with what happened when collapse occured. Allmost? Well one have to have knowledge of the situation in the area five years before. Because that’s when small differences in density together with normal water- and temperature-erosion started. It’s always like the snowball effect. The impact seen has had it’s roots long before it happens.

  12. I’m surprised nobody has pointed this out yet…the whole idea is supported by what? You guessed it…another computer model.

  13. As Les Johnson points out above, the opening statement of this post

    No mention of “climate change” as the driver for the sudden event.

    contradicts the Science Daily article. The justification for this contradiction is supposedly:

    REPLY: that refers to the current paper, not the 2008 news article – Anthony

    But supraglacial lakes are mentioned directly in relation to climate change in a second current paper by the same author:

    http://www.igsoc.org/annals/55/66/a66A049.html

    Supraglacial lake dynamics have become an increasingly important factor in ice-sheet response to climate change, because lakes have been implicated in ice-shelf disintegration and influenced grounded ice-sheet flow through their impact on subglacial hydrology.

    Among the impacts of supraglacial lakes on both grounded and floating ice, none are so powerfully linked to ice-sheet change as those leading to the sudden collapse of the Larsen B ice shelf (LBIS), Antarctica, in 2002. During the decades leading up to the collapse, the number of lakes on the central portion of the ice shelf gradually grew from near zero to 3000

    The research clearly mentions climate change in relation to the breakup for the Larsen B ice shelf. The lakes are the driver for the sudden event, and the lakes were created by warming temperatures. It is very misleading to start off this post with an editorial comment suggesting that there is “No mention of “climate change” as the driver for the sudden event”.

  14. A rather an “emotional” reading!

    “‘explosive’ breakup.” Ah ha. This refers to the collapse of Building 1 of the New York Twin Towers after the airliner exploded within (same for Building 2 by the way but the video of 1 was more … dramatic …. emotional).

    “Domino effect.” Ah ha. This refers to President Richard M. Nixon’s description of the “need” to maintain a war in Vietnam (while perusing ‘Peace Talks’ in Paris) and secretly (but found out quickly) bombing sites (humanitarian and political) in Cambodia (as if Cambodia were Kansas).

    The “70 kPa” and “Stage” color bar left has NO relationship to the “35 kPa” and “Stage” color bar right. Just fantasies of the “emotional” mind. Note that the “boundaries” of the lakes before and after as well as the “ice shelf coast line” are the same (static) in both. Ah ha. “Geographers Dilemma!” ‘Witch’ to choose! Heavens forbid.

    From the “water hammer” to the “domino effect.” Seems the “science” as such is racing backwards to oblivion.

    Next up: Re-imagining The Bronze Age of Modern (well heeled tourist with camera’s mucking about) Glaciology (that was never not now a ‘science’).

    This is now-days part and parcel of GRL: since the “President” of AGU is a … Geographer. Oh dear indeed. “There … I did it again!”

  15. After this extended cold spell many of you armchair scientists have the opportunity to study “ice shelf breakup”. Go down to the local pond or lake and watch as the ice melts from above and below, Gets little pond-lets and holes that grow until the ice looks like swiss cheese and then it drains and collapse as the rotten riddled ice can no longer maintain its’ structure. pg

  16. John F. Hultquist says: January 8, 2014 at 5:58 pm

    The squirrel hunter who named Seal Nunataks was a bit out of his way.

  17. I prefer choice E.
    .
    A Predator’s cloaked dropship’s targeting computer was off and the laser misfired repeatedly trying to burrow down to the Alien’s ancient pyramid, thus shooting the Larsen B Ice Shelf full of holes leading to the lake drainage and inevitable breakup. Also keeping in mind that Predators prefer hot weather (see explanation given to Arnold Swartzenegger, et al by a Sandinista POW) this could have been intentional as a plot to cause purposeful global warming – ZGW as it were – Zenomorph Global Warming.
    .
    Seems as probable and viable an explanation as anything coming from the alarmist crowd these days.

  18. Aphan –

    u need to note Turney’s “scientific” Expedition was a “fake” from the start, if this is true:

    9 Jan: Australian: Anthony Bergin: Saga of Shokalskiy breaks ice on much-needed polar conversation
    The head of the French Polar Institute has called the Russian ship’s cruise, with its assortment of tourists and Australian scientists, a “pseudo-scientific expedition”. It’s interesting that the voyage isn’t part of the official Australian Antarctic Science Program, and was taking paying passengers. The cruise is badged by its operators as the Australasian Antarctic Expedition, appropriating the name of the Australasian scientific team that explored part of the cold continent between 1911 and 1914, led by Douglas Mawson. It’s a bit like stealing the term Anzac for a tourist visit to Gallipoli…
    – The writer, Anthony Bergin, is deputy director, Australian Strategic Policy Institute, and honorary fellow, Antarctic Climate and Ecosystems Co-operative Research Centre.

    http://www.theaustralian.com.au/national-affairs/opinion/saga-of-shokalskiy-breaks-ice-on-muchneeded-polar-conversation/story-e6frgd0x-1226797645337#

  19. There was nothing sudden about the breaking of Larsen B: it was a traditional xmas
    BBC leading news item from at least the early 1980’s, if not the late 1970’s. It took
    over 20 years for Larsen B to “suddenly collapse”.

  20. So what? Ice shelves probably go through cycles of growth and break up. It’s natural. Like trees grow (some for thousands of years), then die, and others grow in their place. The environment is constantly changing and going through cycles which are superimposed on other cycles, upon cycles. Ultimately, it can look like a ‘random walk’. That’s nature. Why are we pining after some broken up ice shelf? It’s no big deal. So what. Did it affect anyone? No. Is it a symptom of anything? No. Would we have cared if we had no satellites up there observing? No. Would we have known? No. Have there been bigger ice shelves in the past? Probably. Does it matter? No.

  21. Take a trip on Google Earth to -64.954:-60.648 and look down from 24km and you will see the extent of meltwater on 1-1-1999. Now move a bit further, to -65.205: -60.267 at the same altitude, and you will see the ice shelf reforming as of 2-2-2010. It broke up because it became unstable; it is reforming because shelves can be expected in that type of bay.

  22. Looking at a bathyspheric maps and ongoing research by the Korean polar institute and others would seem to indicate that the meltwater ponds and the breakup were caused by the eruption of the Jun Jaegyun Seamount.

    A 2002 expedition traced a warm water current from near the iceshelf to the seamount. If warm water undercut the iceshelf and pushed it back from the underwater moraine, it would expose the iceshelf to wave action.

    There are no papers published on the subject yet.

  23. “Observations indicated that the majority of those lakes drained within the final few days before the ice shelf broke up, but scientists were not certain how that could have happened.”
    Speaking as an uneducated peasant, someone pulled the “plugs”.

  24. OK, let’s go over this…recently announced Antartic ice is > continental USA land area. So we have here 1800 SQ MILES/3,000,000 or 0.2% of the Antartic ice breaking up. Now, consider it as a floating, cantelivered beam. Beam theory has a variety of “high stressed points” many of them TENSILE strength of ice is around 1000 PSI. Interestingly this is HIGHER than the compressive strength, and if we talk about a fracture on the sigma 22 plane, it can be as low as 150 PSI. Now the last time I checked, bays as the one this shelf is in, have TIDES. Going up and down a meter or two. That’s quite the flexture. When I put all this together, I LAUGH at this “significance” of this event. A expectoration in to the polar vortex breeze, as I can see.

Comments are closed.