Another Blow to Antarctic Glacial Stability as Larsen C Ice Shelf Cracks Up

Larsen C rift

(Northern edge of Larsen C Ice Shelf is at significant risk of breaking off as a massive rift continues to open within it. The above image shows the rate of rift propagation since November of 2010. Image source: Cryosphere Discussions.)

There’s a 30 kilometer long and hundreds foot deep crack running through West Antarctica’s massive Larsen C ice shelf.

It’s a rift that now stretches from the Weddell Sea — where winds and currents have driven human-warmed ocean waters to up-well along the ocean-contacting faces of the great Antarctic ice sheets — and deep into the interior of this 49,000 square kilometer and 600 to 700 foot tall block of ancient, floating ice.

Over the past few years this rift has been rapidly advancing at a rate of about 2.5 kilometers each year.  Given that the rift has already traversed more than half of the Larsen C ice shelf calving face, a very large break-up could now occur at almost any time.

Larsen C Destabilizing

This evolving situation now threatens to destabilize the entire Larsen C ice shelf — resulting in major losses to a very large block of ice that has been a permanent feature of the Antarctic coastline since at least the last interglacial period 150,000 years ago. Such rapidly evolving risk was the subject of a February 5 communication by a group of glaciologists warning that “significant threats” to “Larsen C ice sheet stability” now existed.

The report notes:

In a change from the usual pattern, a northwards-propagating rift from Gipps Ice Rise has recently penetrated through the suture zone and is now more than halfway towards calving off a large section of the ice shelf (Figs. 1 and 2). The rate of propagation of this rift accelerated during 2014. When the next major calving event occurs, the Larsen C Ice Shelf is likely to lose around 10 % of its area to reach a new minimum both in terms of direct observations, and possibly since the last interglacial period (Hodgson et al.2006)

Connecticut-Sized Break-up Possible

Large ice shelf break-ups have been occurring along the Antarctic Peninsula since the 1970s. As human warming advanced and the heat sink of the southern Ocean increased bottom water temperatures along the Antarctic perimeter, many of the far northern ice shelves and an increasing number of ice bodies closer to the Antarctic interior have lost significant portions of their mass.

Now, Larsen C is at risk of an even worse break-up. For the predicted 10% loss to Larsen C would equate to about 5,000 square kilometers — or an area roughly the size of Connecticut — floating off into the Southern Ocean:

Section of Larsen C vulnerable to break-up

(Larsen C Ice Shelf map with the new rift indicated in red and the potential calving face outlined in blue. Note the previous calving fronts in 1975 and 1988. Image source: Cryosphere Discussions)

It would be yet one more major ice loss for the region, and perhaps a new record loss for an area that has frequently seen Rhode Island sized chunks of ice (around 1,000 square kilometers) break off into the warming world’s seas.

The report goes into further detail about the importance and vulnerability of Larsen C, stating:

The Larsen C Ice Shelf is the most northerly of the remaining major Antarctic Peninsula ice shelves and is vulnerable to changes both to ocean and atmospheric forcing (Holland et al., 2015). It is the largest ice shelf in the region and its loss would lead to a significant drawdown of ice from the Antarctic Peninsula Ice Sheet (APIS). There have been observations of widespread thinning (Shepherd et al., 2003; Pritchard et al., 2012; Holland et al., 2015), melt ponding in the northern inlets (Holland et al., 2011; Luckman et al., 2014), and a speed-up in ice flow (Khazendar et al., 2011), all processes which have been linked to former ice shelf collapses (e.g. van den Broeke, 2005).(Emphasis Added).

Conditions in Context

As mentioned above, during recent years we have seen numerous ice shelves and ice sheets begin to destabilize. In addition, two ice shelves — Larsen A and Larsen B have already completely disintegrated due to human-caused warming.

Larsen C may be most immediately at risk, but the leading edges of the Ronne-Filchner Ice Shelf, The Pine Island Glacier, The Ross Ice Shelf, and the Amery glacier have all shown rapid seaward acceleration. Further, various studies of these increasingly vulnerable ice shelves have shown substantial basal melt coincident with a floating of the ice sheets off grounding lines, leading to a retreat of the anchor points landward.

Major Antarctic Ice Shelves

(Antarctica’s major ice shelves. Image source: Commons.)

Sea-facing ice sheets and ice shelves serve to anchor the great interior glaciers of Antarctica. Loss or destabilization of these anchors would result in more and more rapid flow of land ice into the Southern Ocean. It is for this reason that the destabilization and shattering of ice shelves like Larsen C can have serious implications for the rate of sea level rise over the coming decades.

Overall, nearly 200 feet worth of sea level rise is locked in Antarctica’s glaciers and we are, through a heating of the world’s oceans, ice, and atmosphere, pushing these glaciers to melt and move in an ever-more dramatic and world-altering fashion.

Links:

Newly Developing Rift in Larsen C Ice Shelf Presents Significant Risk to Stability

Shrinking Ice Shelves and The Pine Island Glacier

Commons: The Larsen C Ice Shelf

Hat-tip to Colorado Bob

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72 Comments

  1. climatehawk1

     /  February 23, 2015

    Tweet scheduled.

    Reply
  2. Jacob

     /  February 23, 2015

    Thank you Robert for another great article.

    I’ve been watching developments of the Ice shelves in Antarctica keenly for a few years.

    What is going on down there is very worrisome. Even though it sometimes appears to be happening very slowly to my eye, when I take a step back — I remember that these events are frighteningly fast on a geologic time scale.

    Watching the Wilkens and Larcen B ice shelf disintegrations before my eyes was sobering to say the least and quite ominous as to the future that yet awaits us. The cracks in the Ross Ice Shelf, whose fate will likely live beyond Larcen C, are equally alarming to me as those on the Larcen C shelf that are the subject of this article.

    These events taken into account, as well as the countless others you and your contributors have covered, it boggles the mind how anyone can dare deny how much trouble we and future generations are in.

    Thanks again to you and all others contributing here for your vigilance in being beacons of truth in the face of the sea of obfuscation and denialism.

    Reply
    • Cheers Jacob and thanks for the kind thoughts. We’ve seen quite a lot going on with Antarctica over the past year. It becomes rather clear that the situation there is deteriorating rather rapidly, even on human timescales.

      Reply
  3. wili

     /  February 23, 2015

    Yes, this is definitely worth watching. Something else perhaps worthy of another main post is the discovery of more methane holes in northern Russia:

    http://siberiantimes.com/science/casestudy/news/n0127-dozens-of-mysterious-new-craters-suspected-in-northern-russia/

    Reply
  4. Reblogged this on GarryRogers Nature Conservation and commented:
    Discussion of dangerous Antarctic sea-ice melting.

    Reply
  5. These are extracts from my partner Geoff Sleeman’s book Extinction: The Climatic Time Bomb
    The world’s oceans contain a vast amount of dissolved carbon dioxide. As the sea warms it releases more of its dissolved carbon dioxide into the atmosphere and exacerbates global warming.When rain falls it dissolves some atmospheric carbon dioxide in the form of carbonic acid and this is carried by rivers into the sea.

    The permafrost reservoir has been estimated at about 400 Gigatons of carbon in the arctic. A Gigaton of Carbon is one million tons and is written as 1GtC. Estimates have been made of possible Antarctic reservoirs are another 400 to 600 Gigatons. For comparison the total amount of carbon in the earth’s atmosphere, at present, is 700 Gigatons (700GtC). Permafrost stores carbon both as peat and as methane.

    Floating ice will not raise the sea level directly as it melts but as the ocean surface becomes an efficient absorber of the sun’s heat the ocean temperature will rise with a corresponding expansion of its volume. There are two things that will cause the sea level to rise. One is the melting of land ice ie Greenland & Antarctic – the other the warming of sea water. When the sea water warms it expands its volume just like the mercury or alcohol mixture in the tubes of thermometers.

    The colossal ice sheets covering Greenland and Antarctica are the biggest single ice masses in the world. The weight of the one covering Greenland has formed a basin under its center which is now 300 m below sea level. The great weight of ice, in Greenland and Antarctica, has caused a seismic quiet in both polar areas which will come to light as this ice melts easing and reducing the stabilizing downward pressure on tectonic plates and their fault lines. An increase in earthquakes from this easing is expected and future large earthquakes in these regions could end up having a surprisingly long reach if they propagate tsunamis. This is of the greatest concern in the case of Greenland as the densely populated coastlines of the north Atlantic countries are at risk. DIANA BROADHEAD

    Reply
  6. Reblogged this on jpratt27.

    Reply
  7. Good post — bad news. Thanks for reporting it, Robert.

    Reply
  8. Colorado Bob

     /  February 24, 2015

    The imbalance of glaciers after disintegration of Larsen-B ice shelf, Antarctic Peninsula

    Abstract. The outlet glaciers to the embayment of the Larsen-B Ice Shelf started to accelerate soon after the ice shelf disintegrated in March 2002. We analyse high resolution radar images of the TerraSAR-X satellite, launched in June 2007, to map the motion of outlet glaciers in detail. The frontal velocities are used to estimate the calving fluxes for 2008/2009. As reference for pre-collapse conditions, when the glaciers were in balanced state, the ice fluxes through the same gates are computed using ice motion maps derived from interferometric data of the ERS-1/ERS-2 satellites in 1995 and 1999. Profiles of satellite laser altimetry from ICESat, crossing the terminus of several glaciers, indicate considerable glacier thinning between 2003 and 2007/2008. This is taken into account for defining the calving cross sections. The difference between the pre- and post-collapse fluxes provides an estimate on the mass imbalance. For the Larsen-B embayment the 2008 mass deficit is estimated at 4.34 ± 1.64 Gt a−1, significantly lower than previously published values. The ice flow acceleration follows a similar pattern on the various glaciers, gradually decreasing in magnitude with distance upstream from the calving front. This suggests stress perturbation at the glacier front being the main factor for acceleration. So far there are no signs of slow-down indicating that dynamic thinning and frontal retreat will go on.

    Link

    Reply
  9. Kevin Jones

     /  February 24, 2015

    2:53 a.m. (akst) Fairbanks, Alaska 26F 2:53 a.m. (est) Lebanon, NH -25F….51 F(ing) degrees difference the ‘wrong’ way…

    Reply
  10. Colorado Bob

     /  February 24, 2015

    Acceleration and spatial rheology of Larsen C Ice Shelf, Antarctic Peninsula

    Article first published online: 13 MAY 2011

    Abstract

    [1] The disintegration of several Antarctic Peninsula ice shelves has focused attention on the state of the Larsen C Ice Shelf. Here, we use satellite observations to map ice shelf speed from the years 2000, 2006 and 2008 and apply inverse modeling to examine the spatial pattern of ice-shelf stiffness. Results show that the northern half of the ice shelf has been accelerating since 2000, speeding up by 15% between 2000 and 2006 alone. The distribution of ice stiffness exhibits large spatial variations that we link to tributary glacier flow and fractures. Our results reveal that ice down-flow from promontories is consistently softer, with the exception of Churchill Peninsula where we infer a stabilizing role for marine ice. We conclude that although Larsen C is not facing imminent collapse, it is undergoing significant change in the form of flow acceleration that is spatially related to thinning and fracture.

    Link

    Reply
    • More like The Soon Fraud…

      Reply
    • Eric Thurston

       /  February 24, 2015

      Human nature is interesting. If you torture someone they will tell you what they think you want to hear. If you stuff their pockets with lots of money they will tell you what they think you want to hear…

      Reply
  11. climatehawk1

     /  February 24, 2015

    Behind #climate change denial? “Money. Lots of money.” http://thebea.st/1DOVybv via @jaymichaelson #globalwarming #divest

    Reply
  12. The effects of anthropogenic warming are unfolding so rapidly it’s difficult just trying to keep up with it all, never mind remembering it all. The list of “unprecedented” events is so long I can hardly recall it all. Thank you Robert, for your keen eye and wealth of knowledge that you reliably deliver to many who are desperately craving it. This latest development is indeed troubling. Question for anyone reading- I recently read (but forget where) that the rate of Greenland’s glacial melt has doubled every seven years over the past two decades, and that if this continues Greenland alone would contribute 23 feet of SLR by 2100! A staggering figure much larger than the 4-6ft that is commonly talked about. So much so that I dare not repeat it unless I can confirm it with the very educated author and readers of this site. Thanks! And cheers!

    Reply
    • Colorado Bob

       /  February 24, 2015

      The team used more than 200 million SIRAL data points for Antarctica and some 14 million data points for Greenland to create the elevation maps. The results show that Greenland alone is losing around 375 cubic kilometers of ice per year.

      Compared to data which was collected in 2009, the loss of mass from the Greenland ice sheet has doubled. The rate of ice discharge from the West Antarctic ice sheet tripled during the same period.

      http://www.dw.de/greenland-ice-melting-at-record-speed/a-17869513

      Reply
      • Great link! Thank you for that, and the many great links you provide, Bob! What I find is that even though millions of extremely accurate data points confirm that melting has doubled and tripled in just a few years, everyone is afraid to even ask,”What if this exponential melt continues?” I realize 20 years is a short timespan to draw long term trends from, but let’s be honest-warming isn’t going to stop. If melt continues to accelerate at such rates we will lose pretty much every coastal city on the planet, along with huge areas that grow large portions of food, in the life of kids born today. And they’re still building high-rises in Miami with 30 year mortgages! Please someone tell me I’m incorrect.

        Reply
    • The rate of melt for the ice sheets is proceeding exponentially. There is some debate as to how long this rate of increase can last. Most researchers now expect 3-9 feet of SLR by the end of this Century, with IPCC still showing 3 feet. The U.S. Coast Guard is preparing for 5-6 feet with NOAA expectations in a similar range.

      If the exponentially expanding melt rate continues, we hit two meters, or more than six feet of SLR by mid century, rather than end century.

      It’s worth noting that such a large outflow of cold, fresh water would play havok with ocean circulation, greatly increase ocean stratification, and throw a far worse monkey wrench into the weather than we’ve already seen.

      Reply
  13. And on a personal note, I live in Connecticut and have driven, rode motorcycles and bicycles to every nook and cranny of this state. And while the uninformed routinely dismiss statements like “a Rhode-Island size piece of ice” as trivial and unimportant, I can personally (just barely) picture scraping CT away and leaving an eight hundred foot hole in its place, and the volume of it makes my head spin. Combined with the rapidity with which these events are unfolding it is rather worrying.

    Reply
  14. I can hear the screams from denialists if this were to break off and smash into the Falkland Islands. LOL.

    Reply
  15. James

     /  February 24, 2015

    Tremendous amounts of heat are accomplishing the phase change of ice to water. When the ice is gone, then tremendous amounts of heat will create a sudden lurch in the heating of sea water. Can we expect sea level rise to become unambiguously exponential and rapid when the ice is gone? I can imagine that the world will burn fossil fuels at ever faster rates to cope with this rising problem and thereby create yet one additional positive feedback resulting in even more rapid sea level rise. Oh well, malignant cancers have never been particularly interested in long term survival.

    Reply
  16. Colorado Bob

     /  February 24, 2015

    Looking back at the past Larsen collapses , we stand a good chance of seeing this one go next month.

    Reply
    • Colorado Bob

       /  February 24, 2015

      I went and looked clouds hanging around the last few passes.

      I found this though –
      Hydrogen sulphide eruptions along the coast of Namibia

      Reply
  17. Jared

     /  February 24, 2015

    We better hope those sink holes in Northern Siberia don’t have anything to do with methane being released due to significant human induced warming that has been taking place up there for the better part of a decade. Seems like every monthly temperature anomaly map posted over the last decade has shown Siberia average 2-4 C above the 1951-1980 baseline. Should be starting to see some of sink holes opening up in Canada and Alaska if they are related to no?

    Reply
    • It would seem that relic hydrate concentrations are the key ingredient to this particular brand of human warmed nastiness. That would make Siberia ground zero.

      And, yes, I think it’s fair to say that a leading theory is that these blow holes are an upshot of human caused warming. That said, the overall volumes of methane produced from this particular source, so far, has been small.

      The trend and the violent release mechanism — spontaneous explosion from pockets beneath the ground — however, is not at all promising.

      Reply
  18. Colorado Bob

     /  February 24, 2015

    Ocean circulation change: Sea level spiked for two years along Northeastern North America

    Summary:
    Sea levels from New York to Newfoundland jumped up about four inches in 2009 and 2010 because ocean circulation changed. The unusual spike in sea level caused flooding along the northeast coast of North America and was independent of any hurricanes or winter storms. A new article documents that the extreme increase in sea level rise lasted two years, not just a few months.

    Link

    Reply
  19. Colorado Bob

     /  February 24, 2015


    Coral disease linked to a warming Atlantic

    Summary:
    Over the last four decades, the iconic elkhorn and staghorn corals that dominated Caribbean reefs for millions of years have all but disappeared. According to a new study, ocean warming has played a significant role in this dramatic decline.

    Link

    Reply
  20. Colorado Bob

     /  February 24, 2015

    Ocean acidification slows algae growth in the southern ocean

    Summary:
    Scientists demonstrate for the first time that ocean acidification could have negative impacts on diatoms in the Southern Ocean. In laboratory tests they were able to observe that under changing light conditions, diatoms grow more slowly in acidic water.

    Link

    Reply
  21. Colorado Bob

     /  February 25, 2015

    The Siberian blow outs, have blow-up on the Google news feed –

    Dozens of Methane Blowholes Spotted In Siberia: Why Experts Worry

    Months after conducting investigations of a big black hole that mysteriously appeared in Siberia, researchers from Russia revealed that they have discovered more of these craters, with one of the recently discovered being found to be a big lake surrounded by over 20 baby craters that are filled with water.

    Link

    Reply
    • Colorado Bob

       /  February 25, 2015

      One of the new methane blowholes that experts are interested in is one dubbed B2. Satellite images show that it is a big lake that is surrounded by over 20 small water-filled craters. Analysis of the satellite images show that there were originally no craters and lakes but then the craters started to emerge. Scientists think that the water-filled craters merged and eventually become one large lake.

      Link

      Reply
      • Colorado Bob

         /  February 25, 2015

        Permafrost contains a considerable amount of methane hydrates. An expert estimated that the craters have total explosive power comparable to about 11 tons of TNT.

        Having read several of these articles, all of which seem to be based on the original reporting in the Siberian Times. One thing is clear, these were not explosions where gas was ignited by some spark, but rather methane hydrates reaching a temperature where their phase change occurs from a stable hydrate to a gas very rapidly.
        And looking at how deep some of these holes are, and where they are occurring this not good .

        I am reminded of what I wrote about Dr. Hanson’s phrase ” MONSTERS BEHIND THE DOOR ” over 8 years ago .

        it’s a phrase I caught a few weeks back from the Tom Brokaw special on Global Warming.

        Tom plowed a lot of the same ground that’s been in the news for the past few years, but the show was notable for the above phrase, and what it describes. Dr. Hanson from The Goddard Space Flight Center used it. And like the 50’s SiFi movies it’s the things we don’t know that scare him about Global Warming. One of those doors is beginning to open now, and behind it is the thawing of the permafrost. An emerging subject that’s going to get a lot more attention, and the permafrost in Siberia in particular.

        Thursday, September 07, 2006

        Reply
    • This seems to be going viral. Hopefully concern will raise appropriate response.

      Reply
  22. Colorado Bob

     /  February 25, 2015

    “You are all condemned men ….. We keep you alive to serve this ship …. so row well, and live.”

    Visited my old dead blog for that Hanson thing, and saw my favorite movie quote, name the movie where this quote comes from. And name the actor who said it .

    Hint : In his next epic , he said , “I’ve got my orders , not like that poor fellow, he’s riding the whirl wind.”

    Reply
  23. Colorado Bob

     /  February 25, 2015

    Looking at the Reanalyzer tonight is something amazing .

    It’s a 20 C degree anomaly above average on the North Slope of Alaska, and it’s a 20 C degree anomaly below average from Indiana to Maine .

    Link

    Dr. Jennifer is going to win a Noble Prize, because nature is doing exactly what she predicted it would.

    Someone will go back and find the last year we saw “flat” jet streams , because tonight the jet is a pile of pasta noodles draped on the top of the Earth. And it’s been at it for years , and getting weirder.

    Reply
    • Should get a Nobel Prize…

      Reply
      • Colorado Bob

         /  February 25, 2015

        She will get the Noble. Because she is right, and hundreds of millions will suffer to prove her point.

        Only after that, will she be accepted. She’s a woman after all . Girls don’t make predictions about giant loops in the jet stream.

        Reply
    • Yes, and for me and once a sailor in the Southern California Bight, there is the time, “Before the wind died.” (2006-2007) — and “after”, which is now.

      Point Conception, in the time of sailing ships was called the “Cape Horn of the Pacific.” (See WH Dana’s “Two Years Before the Mast.”) That wind, as it powered down from the NW was dependent upon a frigid and iced up Arctic.

      JF might also be ignored because she was right. One of those really simple and direct ‘rights’ that drive most people crazy who insist upon complications with lots of caveats and maybes.

      DT “once a sailor”

      Reply
  24. Colorado Bob

     /  February 25, 2015

    robertscribbler
    / February 25, 2015

    Good ol’ Charlton Heston.

    Sorry , guess again .

    Reply
    • Damn. Now I have to go and look it up…

      Reply
      • Colorado Bob

         /  February 25, 2015

        He was in as well . The Bridge on the River Kwai –

        Maj. Warden: I belong to a rather rum group called Force 316. Our headquarters is up in the botanical gardens.

        Commander Shears: Protecting rare plants from the enemy?

        Reply
      • Colorado Bob

         /  February 25, 2015

        Jack Warden , nobody ever had better lines , in more movies than Jack. To this day he is the king. No one has ever come close.

        “You are all condemned men ….. We keep you alive to serve this ship …. so row well, and live.”

        Reply
      • Colorado Bob

         /  February 25, 2015

        He was in every great movie of his time, and playing second bananna , but he always had the great lines.
        David Lean made sure of that.

        Reply
      • Colorado Bob

         /  February 25, 2015

        Now there’s one I’m not familiar with. You’ll set me on an old movie binge yet, Bob.

        Ben Hur

        Jack told Charleton who was in charge just before the ship was rammed , and it sank.

        Irony.

        Then Charleton tells Jack –

        On the wreckage , ” We keep you alive to serve this ship …. so row well, and live.”

        Reply
  25. Colorado Bob

     /  February 25, 2015

    * Massive amounts of Saharan dust fertilize the Amazon rainforest We knew this, the ‘new’ is the magnitude of phosphorous transport is now known.

    If what the models forecast is true, and we keep cutting trees as we do. Then this one dust particle is landing on another dust particle. Because the Amazon rainforest will be dead. The cyclone that just sideswiped Australia points to the tropics expanding. There is no reason why one desert near the tropics can’t export dust to a new desert in the tropics.

    By 2100 plants, animals, bacteria, and people will only go to the tropics briefly. Because we will have sawed down every tree there to make decks in Mass., and China.

    On another thread today I looked up the ice melt in Greenland , because someone asked . It’s doubled in 6 years. Antarctica is tripled in 6 years. Does anyone here think our great forests aren’t under going the same collapse?

    And we’re not up in Greenland with torches melting ice , but we are in the tropics chain sawing trees. And this will bite everyone , and it is not in the models.

    And it is another ” MONSTER BEHIND THE DOOR “.

    Massive amounts of Saharan dust fertilize the Amazon rainforest

    http://www.sciencedaily.com/releases/2015/02/150224102847.htm

    Reply
  26. Colorado Bob

     /  February 25, 2015

    On the wreckage , ” We keep you alive to serve this ship …. so row well, and live.”

    Reply
  27. Colorado Bob

     /  February 25, 2015

    Now back to the grim wreckage here everyday.

    Reply
  1. Warm, Storm-Force Winds Blowing Up from the Equator Change West Antarctic Winter to Summer | robertscribbler
  2. Warm, Storm-Force Winds Blowing From the Equator Flip West Antarctic Winter to Summer | RClimate

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