Antarctica’s 4th Largest Ice Shelf is About to Melt Back to its Smallest Area Ever Recorded

These days, there’s a big debate raging in the sciences over the issue of Antarctic melt. On the one side, you have a growing flood of data indicating that many ice shelves are thinning, that surface melt is more prevalent than previously thought, and that glaciers are threatening to destabilize at faster than previously expected rates. On the other side, we still have a number of hold-outs who rightly claim that ice shelves have always calved and that many of the processes we now observe have always been in place.

The scientific messengers sending these various indicators of Antarctic destabilization are cautious not to draw too many conclusions. But the data itself is pretty stark — which has been enough to produce some qualified, if very appropriate, warnings that Antarctica could be tipping toward instability far faster than previously imagined.

(The northern end of a massive rift in the Larsen C Ice Shelf is spawning numerous smaller ice bergs off a larger, Delaware-sized monstrosity. Now, only 3 miles of ice connect this emerging berg to the Larsen C ice mass. Once the berg separates, Larsen C will break back to its smallest area ever recorded. Image source: Project MIDAS.)

Of course the ice shelves named Larsen A and Larsen B existed throughout human times until they were only recently melted by warmth creeping up the along the Antarctic Peninsula in both the air and the water. Meanwhile, the Larsen C ice shelf is about to shatter off a very large 5,800 square kilometer ice berg even as several smaller ice bergs also appear ready to form. This event, which is now imminent in the coming days, weeks, or at most, months, will break the Larsen C ice shelf back to its smallest area ever recorded even as it marks a period of increased instability and risk of ice shelf loss.

For recent scientific assessments show that Larsen C is lowering in the water — an indication that the shelf is thinning. Furthermore, when the gigantic, Delaware-sized, ice berg and its smaller siblings break off they will take with them outer sections of a stabilizing compression arch. The compression arch, somewhat like the arch of a flying buttress, helps to balance structural stresses for the ice shelf. If it were to be compromised in total, according to glacier scientists like Dr. Eric Rignot, Larsen C would soon be adding its name to the list of various ice shelves around the world that have already fallen due to the warming airs and waters produced by human-caused climate change.

(The large ice berg that is presently breaking away from Larsen C appears to have bisected both southern and northern sections of the ice shelf’s stabilizing compression arch [indicated in the upper images by a solid gray line]. Loss of parts of the compression arch are an indication that Larsen C could become considerably less stable in the near future. However, some science indicates that the ice berg presently breaking off from Larsen C does not compromise key stability features. The nearer term future for the greatly reduced Larsen C Ice Shelf is therefore uncertain. Image source: Marine Ice Regulates Future Stability of Large Antarctic Ice Shelf.)

As with most predictive measures, however, the present trend isn’t perfectly clear with regards to the ultimate fate of Larsen C in the near future. Some studies have indicated that the section of ice breaking off is not crucial to the ice shelf’s stability. And the sections of the compression arch that are being taken out are closer to the outer edge of the ice shelf — not representing the key central arch region.

Overall, however, this story for Larsen C isn’t a good one. The shelf is thinning, it is about to reach its smallest area ever recorded, and even the loss of some outer sections of the compression arch are enough for a number scientists to express qualified concern. Larsen C didn’t show this level of instability back in the 90s or 2000s, so the overall trend here is more toward melt and instability for this 4th largest ice shelf in Antarctica.

UPDATE:

As of 7/10/2017 through 7/12/2017, rift formation had finally met open water and the large ice berg breaking away from Larsen C had finally calved. From the Project MIDAS website:

A one trillion tonne iceberg – one of the biggest ever recorded – has calved away from the Larsen C Ice Shelf in Antarctica. The calving occurred sometime between Monday 10th July and Wednesday 12th July 2017, when a 5,800 square km section of Larsen C finally broke away. The iceberg, which is likely to be named A68, weighs more than a trillion tonnes.  Its volume is twice that of Lake Erie, one of the Great Lakes.

Links:

Project MIDAS (and associated scientists)

Antarctica is About to Lose an Enormous Piece of Ice

Marine Ice Regulates Future Stability of a Large Antarctic Ice Shelf

Maximum Buttressing of Larsen C Ice Shelf

Antarctica’s Ice Shelves Thin — Threaten Significant Sea Level Rise

Scientific Hat tip to Dr. Eric Rignot

Scientific Hat tip to Dr. Richard Alley

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70 Comments

  1. Suzanne

     /  July 11, 2017

    Even an article at Business Insider..in June.
    http://www.businessinsider.com/antarctica-giant-iceberg-breaking-off-2017-6
    Nice graphics…and a video to compliment the article..
    http://www.businessinsider.com/antarctica-giant-crack-growing-fast-larsen-c-2017-5

    Reply
  2. wili

     /  July 11, 2017

    And on the other end of the globe: http://arctic-news.blogspot.de/2017/07/rain-over-arctic-ocean.html

    “Rain Over Arctic Ocean”

    Reply
  3. Suzanne

     /  July 11, 2017

    And as the ice melts at both poles..Trumps tells the Mayor of Tangiers Island, not to worry about SLR.
    (This falls under the category…I don’t know whether to laugh or cry)

    https://thinkprogress.org/trump-to-island-mayor-dont-worry-about-sea-level-rise-80c271ecd14

    The island, mostly Republican who voted for Trump by a whomping 87%, is being threatened by SLR. CNN did a piece on what the residence are facing. Trump saw the piece, and called the Mayor, who strongly voiced his support for Trump in the piece.

    Trump called a shocked Eskridge, who said the president explained he “had to call” such a strong supporter. Trump added, “You’ve got one heck of an island there.”
    “This is a Trump island; we really love you down here,” Eskridge replied. “The stuff you are doing is just commonsense… I believe you came along for such a time as this.”
    The subject of the call then turned to the island’s fate. Trump “said not to worry about sea-level rise,” Eskridge explained. “He said, ‘Your island has been there for hundreds of years, and I believe your island will be there for hundreds more.’”

    Reply
  4. Suzanne

     /  July 11, 2017

    “New dataset provides the most complete look at climate of the last 2000 years” at Future Earth today…
    http://futureearth.org/blog/2017-jul-11/new-dataset-provides-most-complete-look-yet-climate-last-2000-years

    The natural world holds a wealth of information about how hot or cool the planet was in the past – from records stored in tree rings and tropical corals to clues hidden in glacier ice and tiny fossils at the bottom of the ocean. Now, a new database taps into that information, creating the most complete timeline of past shifts in the globe’s temperatures over the last 2000 years. The effort, which was published today in Scientific Data, includes 692 records of historic climate change from 648 sites around the world.

    Reply
    • Greg

       /  July 12, 2017

      The temperature graph from their work:

      Reply
      • Suzanne

         /  July 12, 2017

        Thanks for posting..

        Reply
      • Note that present temperatures are 0.3 to 0,4 C warmer than when this data set ended in 2000.

        Reply
      • wili

         /  July 12, 2017

        Yes, this graph really gets across why some estimates of how much of GW since about 1800s range above 100%…we would probably have cooled even further along the trend line that this graph nicely shows (consistent with the trend for the last 8000 some years) had it not been for the enormous eruptions of CO2 and CH4 from industrial society.

        Reply
        • Syd Bridges

           /  July 13, 2017

          That graph sort of fired one of my few remaining brain cells. It reminded me of some sort of stick. A hickory stick perhaps?

  5. climatehawk1

     /  July 11, 2017

    Tweet scheduled.

    Reply
  6. Greg

     /  July 11, 2017

    The begininnings of this era’s destruction of our Earth’s critical A.C. system is an inconvenient truth. Robert stoically reminds us.
    Another month to go to see the sequel to Al Gore’s original documentary. Hoping we get the word out and, like last time this movie will reenergize and dominate public discourse.

    Reply
    • Raul M.

       /  July 12, 2017

      We are moving closer to “weather terror” being a common response to the up close and personal nature of local weather.

      Reply
    • The energy charging this impending release is amazing. Al Gore was right in so many ways. The people who didn’t listen were basically fighting against history and nature combined.

      Reply
  7. Greg C

     /  July 12, 2017

    I can’t understand why this hasn’t calved yet. It’s been down to 5km (3 miles) for about a week now. I guess you just never know with ice. Still if it’s still clinging on much past next week, I’ll be very surprised.

    Reply
  8. Good climate article by David Wallace-Wells in the New York Magazine this week:
    http://nymag.com/daily/intelligencer/2017/07/climate-change-earth-too-hot-for-humans.html

    Reply
  9. Suzanne

     /  July 12, 2017

    And a piece at Vox…”Did that New York magazine climate story freak you out? Good.
    https://www.vox.com/energy-and-environment/2017/7/11/15950966/climate-change-doom-journalism

    Two basic questions that have been raised: whether the article is accurate and whether it is “useful.” On both counts, the piece is on far more solid ground than its critics acknowledge.

    Yes, it is mostly accurate
    I’ve already run into about a dozen tweets, Facebook comments, and emails to the effect of, “Michael Mann debunked that piece.” Except he didn’t, not really.
    ____________
    Bottom line from this article…Don’t throw out the baby with the bathwater.

    Reply
    • Suzanne

       /  July 12, 2017

      Here is an interview with David Wallace-Wells on his article…
      http://gothamist.com/2017/07/10/climate_change_ny_mag.php

      First question and answer…from the interview:

      I guess my first question is, is there any hope?
      Oh, I would say there’s quite a lot of hope. The conceit of the piece was to survey worst case scenarios in order to ultimately motivate people to action. But one of the things that I worried about as I put it together was that readers would have a fatalistic response to it and I don’t really think that that’s appropriate. At some point in the piece, I talk about almost all of the damage that we’ve done to the planet, in the sense that global warming has occurred over the course of the lifespan of the Greatest Generation. So ultimately, I think, this could be as short a story as a story of two generations. But at the very least we have another lifespan to figure it out, and to take the necessary actions to forestall at least the gruesome worst case scenarios that I sketched out in the piece.

      Reply
    • After reading the responses, the piece, in my view, does not fall into classic doomerism — which provides apathy and hopelessness as its end message. The intent of the piece was clearly to try to wake people up to the potentials of future worst case scenarios and to express how urgently we need to respond to climate change. The article did get these things right in broad brush.

      Reply
    • Tweeted, thanks. Especially liked the part at the end where Roberts says he thinks nobody really knows that much about how to effectively communicate this issue to the public.

      Reply
  10. I cannot believe I just heard an NPR news report that said “Scientists say icebergs break off all the time and this is nothing unusual” re iceberg the size of Delaware breaking off that could interfere w shipping lanes…that would be NPR’s focus

    Reply
    • Suzanne

       /  July 12, 2017

      Yikes! I would say that their report missed the mark by a wide margin.

      Reply
    • In context, Larsen C’s melt back to its smallest area ever recorded following the loss of Larsen A and B is a classic indicator of warming and human forced climate change. Yes, Ice bergs do calve and large ones do break off. But saying this event is normal does not take into account the larger trends that are ongoing in Antarctica.

      Reply
    • Here’s NPR’s article:

      http://www.npr.org/sections/thetwo-way/2017/07/12/536818782/massive-iceberg-breaks-free-in-antarctica

      Nor is it clear whether climate change is behind this breakup. Although climate change has been responsible for melting in other parts of Antarctica, such as the Pine Island Glacier, researchers believe the story on the Antarctic Peninsula is more complicated. “Icebergs are calving all the time in Antarctica, and really that forms part of the natural life cycle of any ice shelf,” Hogg says.

      Researchers will have to continue their studies to find out whether Larsen C is being affected by climate change.

      I guess everything is fine?

      Reply
  11. wharf rat

     /  July 12, 2017

    “This event, which is now imminent in the coming days, weeks, or at most, months, ”

    Best timing ever? How many minutes between publication of this post and the announcement?

    Reply
  12. All eyes on British Columbia . my home is on Vancouver Isl but I have friends who called me from the interior, Hes watching everything burn around him , mass evacs, says he could hardly breath . B C on fire with not an end in sight : http://globalnews.ca/news/3592349/b-c-wildfire-status-wednesday-all-eyes-on-the-weather/ . and again from The Buzz : http://victoriabuzz.com/2017/07/wildfires-continue-rage-across-bc-photos/ . Haven’t heard from them for a couple of days , Giving them my best wishes along with the rest of them . Wild life is really taking a beating …so sad !!

    Reply
    • wili

       /  July 12, 2017

      Best wishes for your friend. Those are quite the fires!

      Reply
    • Thanks for this, Jeff. Hope your friend stays safe.

      Reply
    • PlazaRed

       /  July 12, 2017

      I was working in BC Vancouver area the whole of November last year and I kept telling the people there about fire dangers with hot days and vast amounts of undergrowth.
      My warnings of fire dangers were universally laughed at, as if it was something that happens somewhere else. I mentioned that somewhere else might be getting a lot closer to BC!
      The fact is that if it rains a lot and is not too cold the undergrowth grows and then dries out to be a massive fire danger.
      I will read up on the links you included.
      Hope thing improve very soon.

      Meanwhile in southern Spain and in fact most of the country we are having very hot temps. 45/C today and for several more days in the south. The all time recorded record temps here were about 47/C back in around 1996.

      Reply
      • +1

        Thanks for speaking out, despite the difficulty.

        Reply
      • You are spot on , they had torrential flooding for weeks , then the sun came up and dried it all out , then the lightning came and set it ablaze . Hell ,cooking up some breakfast !!!

        Reply
        • PlazaRed

           /  July 12, 2017

          It rained every day except one in the month I was there, they said it had rained a lot more before November. Then it rained all winter and snowed a bit, there were waterfalls all over the place.
          Then in a few days they told me it stopped raining, dried out and got very hot.
          As some say, “you’ve got to believe me!” which is in fact easy but the undergrowth was about 10 feet or 3 meters tall and it looked like Hell waiting for somebody to throw in a match!
          Nobody seemed to believe in their cocoon like worlds that there would every be forest fires in a place where they had little expiriance of them, houses everywhere with masses of trees right up to the walls and over the top of them.
          I was in the Gibsons, Roberts Creek area and there is only one road that effectively goes nowhere except to a ferry at either end. No real way out if Hell gets a match thrown into it.
          I sure hope they don’t get big fire there this summer.

  13. Ronald

     /  July 12, 2017

    Slightly off-topic, but related and at least as relevant: I suspect, that the Amazon basin, and in particular the eastern parts of the Amazon, may be experiencing another exceptionally dry year this year. I have checked precipitation data at Accuweather, and I found that several weather stations particularly in the eastern Amazon showed strikingly low rainfall for the months Jan through May 2017, in some cases only 30-50% of long-term normal.
    For instance Manaus/Borba/Manicoré show alarmingly low cumulative rainfall of only 461 mm, against 1365 mm normal, or 34% (!). Also Coari, Manacapuru, Tefé, Humaitá, Lábrea Parintins, Maues show (much) lower rainfall than normal. As you probably know, Jan-May is by far the most important rainy season in that region.
    I realize that I do not know how reliable these data are, e.g. quoted ‘normal’ rainfall was often very wrong. But some climate models predict more frequent El Nino’s, or even an extended ‘El Nino like’ period.
    Maybe you possess or can get more reliable data, for instance from te Brazilian meteorological service. Anyway, it would be very relevant to find out what the present situation in the Amazon is with regard to drought.

    Reply
  14. wili

     /  July 12, 2017

    methane radiative forcing is about 25% higher than previously estimated in AR5 for shortwave forcing:

    M. Etminan et al. Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing, Geophysical Research Letters (2016). DOI: 10.1002/2016GL071930

    http://onlinelibrary.wiley.com/doi/10.1002/2016GL071930/abstract;jsessionid=4BD7EE5DBE1525CC15B5806E5EBEC6F4.f03t01

    Abstract: “New calculations of the radiative forcing (RF) are presented for the three main well-mixed greenhouse gases, methane, nitrous oxide, and carbon dioxide. Methane’s RF is particularly impacted because of the inclusion of the shortwave forcing; the 1750–2011 RF is about 25% higher (increasing from 0.48 W m−2 to 0.61 W m−2) compared to the value in the Intergovernmental Panel on Climate Change (IPCC) 2013 assessment; the 100 year global warming potential is 14% higher than the IPCC value. We present new simplified expressions to calculate RF. Unlike previous expressions used by IPCC, the new ones include the overlap between CO2 and N2O; for N2O forcing, the CO2 overlap can be as important as the CH4 overlap. The 1750–2011 CO2 RF is within 1% of IPCC’s value but is about 10% higher when CO2 amounts reach 2000 ppm, a value projected to be possible under the extended RCP8.5 scenario.”

    “Plain Language Summary
    “Radiative forcing” is an important method to assess the importance of different climate change mechanisms, and is used, for example, by the Intergovernmental Panel on Climate Change (IPCC). Increased concentrations of greenhouse gases, such as carbon dioxide, methane and nitrous oxide, are the major component of the human activity that led the IPCC, in its 2013 Assessment, to conclude that “it is extremely likely that human influence is the dominant cause of warming since the mid-20th century.” In this letter, we report new and detailed calculations that aimed to update the simpler methods of computing the radiative forcing that have been used in IPCC assessments, and elsewhere. The major result is that radiative forcing due to methane is around 20-25% higher than that found using the previous simpler methods. The main reason for this is the inclusion of the absorption of solar radiation by methane, a mechanism that had not been included in earlier calculations. We examine the mechanisms by which this solar absorption causes this radiative forcing.The work has significance for assessments of the climate impacts of methane emissions due to human activity, and for the way methane is included in international climate agreements.”

    See also:

    https://phys.org/news/2017-01-effect-methane-climate-greater-thought.html

    Extract: “Research led by the University of Reading indicates that emissions of methane due to human activity have, to date, caused a warming effect which is about one-third of the warming effect due to carbon dioxide emissions – this methane contribution is 25% higher than previous estimates.”

    Reply
  15. entropicman

     /  July 12, 2017

    Just a bit of whimsy, but A68 is being quoted as massing 1 trillion tons.

    1mm of sea level rise is a volume change of 360 cubic kilometres, the 3.2mm annual sea level rise requires 1150 cubic kilometres or 1.15 trillion tons.

    Good job that it was already floating, bit it does help one visualise the scale of the problem.

    That iceberg is the equivalent of a year’s sea level rise in one lump.

    Reply
  16. …and there it goes…
    http://www.bbc.com/news/science-environment-40321674

    I personally find this particularly distressing since it was the collapse of the Larson B shelf in 2002 that focused my attention on global warming. Fifteen years and now this…

    Reply
    • DJ

       /  July 12, 2017

      Not to worry, I read the Guardian article and have come away feeling reassured by the experts that there’s nothing to be concerned about. I’m not going to echo the quotes here, but read the article and you’ll see what I mean.

      Seriously, though and without sarcasm, the Guardian reporting, or more specifically the quoted comments from the scientific community on this event give me very little hope that the necessary public sense of urgency will be generated before we’ve already gone over the cliff. Arctic melting, Northern hemisphere burning, heat and rainfall records everywhere, and the expressed sentiment from the experts on this event is essentially ‘nothing unusual to see here’. That seems irresponsible to me…

      Reply
  17. Two reports, not good for the Middle East:
    1. https://phys.org/news/2017-07-stalagmites-iranian-cave-grim-future.html
    Stalagmites from Iranian cave foretell grim future for Middle East climate.

    The researchers found that climate during the last 70 to 130 thousand years, including during the last interglacial as recorded in the interior of the Middle East, is closely linked to the climate of the North Atlantic region. By comparing their findings with others, they saw a close connection between water availability and enhanced solar insolation across the mid-latitudes of Eurasia. The study showed that solar insolation is not returning to high values relative to today until another 10,000 years from now.

    2. and the related:
    https://phys.org/news/2015-07-abrupt-climate-cradle-civilization.html#nRlv
    Study finds abrupt climate change may have rocked the cradle of civilization.

    “The high-resolution nature of this record afforded us the rare opportunity to examine the influence of abrupt climate change on early human societies. We see that transitions in several major civilizations across this region, as evidenced by the available historical and archeological records, coincided with episodes of high atmospheric dust; higher fluxes of dust are attributed to drier conditions across the region over the last 5,000 years,” said Arash Sharifi, Ph.D. candidate at the department of marine geosciences and the lead author of the study.
    (the graph https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2015/studyfindsab.png)

    Reply
  18. On depletion of the Ogallala Aquifer.
    Groundwater pumping drying up Great Plains streams, driving fish extinctions
    https://phys.org/news/2017-07-groundwater-great-plains-streams-fish.html#nRlv

    Farmers in the Great Plains of Nebraska, Colorado, Kansas and the panhandle of Texas produce about one-sixth of the world’s grain, and water for these crops comes from the High Plains Aquifer—often known as the Ogallala Aquifer—the single greatest source of groundwater in North America. A team of researchers, including Colorado State University Professor Kurt Fausch and Jeff Falke, a CSU alumnus and an assistant professor at the University of Alaska Fairbanks, have discovered that more than half a century of groundwater pumping from the aquifer has led to long segments of rivers drying up and the collapse of large-stream fishes.

    If pumping practices are not modified, scientists warn that these habitats will continue to shrink, and the fish populations along with them.

    The research team combined modeling from the past and future to assess changes in Great Plains streams and their fish populations associated with groundwater pumping from the High Plains Aquifer. The findings have implications for watersheds around the world, because irrigation accounts for 90 percent of human water use globally, and local and regional aquifers are drying up.

    Fausch said the study results are sobering. Based on earlier observations and modeling by Falke and a team of graduate students and faculty at CSU, the Arikaree River in eastern Colorado, which is fed by the aquifer and used to flow about 70 miles, will dry up to about one-half mile by 2045.

    “You have this train wreck where we’re drying up streams to feed a growing human population of more than 7 billion people,” Fausch said.

    Fausch described the situation as a “wicked problem,” one with no good solution. “More water is pumped out every year than trickles back down into the aquifer from rain and snow,” he said. “We are basically drying out the Great Plains.”

    Reply
  19. PlazaRed

     /  July 12, 2017

    The evening Spanish TV 9pm news have been trying to get the message across of the size of the new iceberg and have stated that its 10 times bigger than Madrid, the capital city of about 5 million people. Plenty of photos and videos, along with explanations in easy to understand terms.
    They really do try hard to inform people of global warming and climate change here, being in the front line slightly north of the Sahara Desert here and presently suffering from a wave of hot dry Saharan air. The desert is about 1.5 times the size of the USA
    Our dam levels are very low, down to 30% capacity in some areas and still 3 months of hot summer weather to come; no chance of any rain of course in the summer here.

    Reply
  20. A Twitter reader says 5,800 sq-km, not 5,800 sq-mi. That sounds correct to me, as 5,800 sq-mi would be nearly twice the size of Delaware.

    Reply
  21. Robert McLachlan

     /  July 13, 2017

    All the mainstream media are running with the story “nothing to see here”. For example, Adrian Luckman’s views expressed in the Guardian and theconversation.com, “there is no direct evidence to link its recent growth to either atmospheric warming, which is not felt deep enough within the ice shelf, or ocean warming, which is an unlikely source of change given that most of Larsen C has recently been thickening. It is probably too early to blame this event directly on human-generated climate change.”

    In fact, that linked Science article states that Larsen C has been thinning:

    “Volume loss from Antarctic ice shelves is accelerating”, Paolo et al Science, 2015: “On the eastern side of the Antarctic Peninsula… the regional ice-shelf thinning rate of 3.8 ± 1.1 m/decade is about half of that on the western side. The onset of thinning for Larsen C has progressed southward, which is consistent with climate-driven forcing discussed in earlier studies. The highest thinning rates on Larsen C (with local maximum thinning of 16.6 ± 8.1 m/decade) are near Bawden Ice Rise.”

    The Bawden Ice Rise is exactly where the iceberg finally detached.

    The Paolo study does find that the rate of thinning was slowing as of 2008.

    On the other hand, it clear that air temperatures are colder at Larsen C than at Larsen A and B (further north) and than the west coast of the peninsula – about 3 degrees colder as I read it, and there are no reports of extensive surface melting.

    It’s possible that all the other, adjacent shelves collapsed because of global warming, but that this, slightly colder one, is still behaving normally. But it looks sure looks suspicious!

    Reply

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