New Research: East Antarctic at Risk of Unstoppable Melt

May 5, 2014

Big Story. The East Antarctic Ice sheet – the world’s icebox, once thought all but impervious to melt on any meaningful time scale, is , on deeper inspection, much more vulnerable than we supposed. The video above, from December, fleshed that idea out.

Now, new research adds to the picture.

Climate News Network:

The East Antarctic ice sheet is thought by most scientists to be stable. But a German team says it has found how part of it could in time melt unstoppably.

LONDON, 4 May – Part of the East Antarctic ice sheet may be less stable than anyone had realised, researchers based in Germany have found.

Writing in Nature Climate Change, two scientists from the Potsdam Institute for Climate Impact Research (PIK) say the melting of quite a small volume of ice on the East Antarctic shore could ultimately trigger a discharge of ice into the ocean which would result in unstoppable sea-level rise for thousands of years ahead. http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2226.html

Their findings, which they say amount to the discovery of a hitherto overlooked source of sea level rise, appear unlikely to happen any time soon. They are based on computer simulations of the Antarctic ice flow using improved data of the ground profile beneath the ice sheet.

“East Antarctica’s Wilkes Basin is like a bottle on a slant,” said Matthias Mengel, the lead author of the study. “Once uncorked, it empties out.” The basin is the largest region of marine ice on rocky ground in East Antarctica.

iceplug

The Wilkes Basin; subglacial area and model domain. The Wilkes Basin (labelled blue shadings) is the largest region with topography below sea level in East Antarctica. At George V Coast, the Cook and Ninnis ice streams drain into the Southern Pacific Ocean and rest on deep palaeo-troughs. Our model domain (hatches) extends to the present ice divides.

At the moment a rim of ice at the coast holds the ice behind it in place, like a cork holding back the contents of a bottle. The air over Antarctica remains cold, but oceanic warming can cause the ice on the coast to melt. This could make the relatively small “cork” disappear.

Once it had gone, the result would be a long-term sea level rise of three to four metres. “The full sea-level rise would ultimately be up to 80 times bigger than the initial melting of the ice cork,” says the study’s co-author, Anders Levermann. “Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk.”

Nature Climate Change:

Changes in ice discharge from Antarctica constitute the largest uncertainty in future sea-level projections, mainly because of the unknown response of its marine basins1. Most of West Antarctica’s marine ice sheet lies on an inland-sloping bed2 and is thereby prone to a marine ice sheet instability345. A similar topographic configuration is found in large parts of East Antarctica, which holds marine ice equivalent to 19 m of global sea-level rise6, that is, more than five times that of West Antarctica. Within East Antarctica, the Wilkes Basin holds the largest volume of marine ice that is fully connected by subglacial troughs. This ice body was significantly reduced during the Pliocene epoch7. Strong melting underneath adjacent ice shelves with similar bathymetry8 indicates the ice sheet’s sensitivity to climatic perturbations. The stability of the Wilkes marine ice sheet has not been the subject of any comprehensive assessment of future sea level. Using recently improved topographic data6 in combination with ice-dynamic simulations, we show here that the removal of a specific coastal ice volume equivalent to less than 80 mm of global sea-level rise at the margin of the Wilkes Basin destabilizes the regional ice flow and leads to a self-sustained discharge of the entire basin and a global sea-level rise of 3–4 m. Our results are robust with respect to variation in ice parameters, forcing details and model resolution as well as increased surface mass balance, indicating that East Antarctica may become a large contributor to future sea-level rise on timescales beyond a century.

 

Advertisements

44 Responses to “New Research: East Antarctic at Risk of Unstoppable Melt”


  1. Why all the thumbs down? It was on-topic, and interesting to read an old Walter Sullivan story.

    http://en.wikipedia.org/wiki/Walter_Sullivan_(journalist)

    • omnologos Says:

      Not sure why anybody would care about thumbs but thanks anyway 8-D

    • dumboldguy Says:

      Who knows??? It WAS interesting to see that someone was thinking about East Antarctica’s ice sheets 34 years ago and what could cause them to flow more rapidly.

      Maybe the strange “message” that Omno posted with the link precipitated some “knee-jerk”?

      The thinking behind this piece is really scary—-another tipping point to be wary of?

      PS to Omno. “Not sure why anybody would care about thumbs…” is a statement from one who is in massive denial. YOU should care, because you seem to be the all-time thumbs down record holder on Crock, and they DO have meaning whether you want to admit it or not..


    • What does “8-D” mean?

      • dumboldguy Says:

        My guess is that it’s a wide grin in text or email “speak” by someone who wears glasses (like Omno). 😀 would be a wide grin w/o glasses.

        Do you know about “ass-icons” (_?_) = “dumb ass”, (_! = “half assed”, (__!__) = “fat ass”, (_E=MC2_) = “smart ass”

        Do you know who this is? 8D(_?_)

      • omnologos Says:

        It’s a wide smile, or a laugh. The former, in this case.


      • Thanks for the emoticon lesson guys. Why the knee-jerk barking at our young commenter, DOG? Give him a break. 🙂

        Back to the concept discussed by Andrew Sullivan. If a massive chunk of the Antarctic ice sheet were to suddenly slip into the ocean, the average sea surface temperature would decline, which would probably result in a temporary decrease in the global average temperature. However, during that period the Earth would be accumulating more heat because the outbound forcing from the surface would decrease.

        • omnologos Says:

          Walter, not Andrew. Been reading too many Conservative writers, haven’t you Charles 😉

        • dumboldguy Says:

          It is not reflexive “knee-jerk barking” that I do with Omno, Charles. I spent my professional career (and even before) as a “sheep dog”, and devoted much energy to “barking” science, rational thinking skills, just plain common sense, and proper behavior into “young commenters”. I still get thank-you’s for my efforts 40+ years later.

          Omnologos is more than a “young commenter”. He has some serious “issues”, as I and others have pointed out many, many times here (including via the “thumbs” that Omno denies have any significance). I won’t pile on him any more in this post—-suffice it to say that he and I would have spent much time together back in the day, and I would have “cured him or killed him”. You do him no favors by being overly indulgent—-he needs help from us.

          Your “Back to the concept discussed by Andrew Sullivan…..” comment elicits a small “what??” in my mind. “Massive chunks of the Antarctic ice sheet” are not going to “suddenly slip into the ocean” to start with, and I don’t quite follow the rest.


          • DOG,
            I haven’t always been easy on Omno – “I see that you still loyally includes a link to “How Science Will Get Rid of the AGW Dogma” authored by Omnologos, our resident philosopher, in which vague analogies comprehensibly displace scientific integrity.”

            Now that I’ve established my Omno bashing credibility, let’s admit that we’ve all been wrong about something, and most of us can change our minds – if given a little space. You and I have more in common than you might imagine. Although, I’m less amusing and more patient. Patience pays off if the goal is persuasion. Not always, but often enough.

            The “massive chunks of ice slipping into the ocean” was a paraphrase of Sullivan’s hypothetical scenario which is an extreme case of the melting of the East Antarctic “cork” unleashing a rapid ice flow. It was a playful take on an unlikely scenario, but I stand by the science. If enough land ice to suddenly raise sea level by say 100 mm, were to slip into the ocean, it would cool the upper level of the ocean. A cooler surface emits less energy. (Let’s ignore albedo changes related to ice flowing into lower latitudes.) If the Earth emits less energy and solar insolation is constant, the Earth will heat up (gain thermal energy) faster during that period.

            Your discussion below is about a more likely scenario in which the ice melts rather than slips into the ocean.

            Anyway, this exchange is a good example of why it’s better to just let stuff go. Peace.

          • dumboldguy Says:

            You and I have much in common—-I seldom disagree with anything you say here, and then only on small points. I don’t know about “amusing”—-I think we tend to chuckle about the same things—-but you are definitely more patient. I employed more “persuasion” when I was “smartyoungguy” drawing a paycheck—-now that I’m retired and draw pensions, I tend to be impatient and somewhat curmudgeonly—-“dumboldguy”.

            I understood the “cork” business and that “rapid” is a relative term, but the “science” you stand by sounds a little “daveburtonish” (forgive me for that).

            100 mm is about 4 inches, and by the time that chunk of ice melted and the cold fresh water layer spread, the winds and currents would cause it to mix into the lower ocean layers (average depth 2+ miles), and the effects on temperature would likely be minimal. What you say is certainly “playful” and theoretically remotely possible, but hugely unlikely, hence my confusion. It might have more localized thermohaline circulation impact, similar to the Laurentide ice sheet melt and the emptying of Lake Agassiz as redsky mentioned.

            “Anyway, this exchange is a good example of why it’s better to just let stuff go. Peace”. Agreed (mostly—small woof).


          • Okay DOG. This is fun. (The thundering herd has moved on.) I agree that the 1984 article’s scenario is totally hypothetical. But let’s contemplate it – even if doing so is admittedly daveburtonish. After a moment of thought and considering your natural born combative personality – I’m not offended – much. (Sheesh)

            First of all, IMO, the mixing between the upper “mixed layer” and the deep ocean is too slow to be much of a factor relative to the time it would take our Attack Of The Icebergs (copyright) to melt. The upper layer’s depth ranges between 10m and 200m. So let’s approximate an average depth of 100m to keep the arithmetic simple. 100 mm of added water would be 1/1000 of the total weight. Assume that the added ice were -10C and the water temp is about 50C.

            The upper level temperature would fall by ((60+79.72)/1000) = .14 C

            Your turn. Woof.

  2. redskylite Says:

    That is the best made video I’ve seen yet on crocks, credible commentators and a stark warning.

    Surrealistically we are talking about something that would effect generations a century or two ahead, and seems so remote to us all today.

    Not only are we talking about massive sea level rise far away from Antarctica, we are talking of Ocean currents being stalled or stopped that will have massive repercussions on climate (see the Laurentide Ice Sheet melt in North America).

    What on earth is it that stops people from accepting the facts and acting ? Is denial and argumentativeness in our blood ?

    whttp://www.youtube.com/watch?feature=player_embedded&v=RaD3ax2j3Ks

    • dumboldguy Says:

      (see the Laurentide Ice Sheet melt in North America).

      The link and this post lead us to what would happen if the “thermohaline conveyor belts” shut down because of too much fresh water from ice sheet melt. BIG trouble, although I did read a fictional account of some geo-engineering that was conducted to restore the flow—-100+ super tankers were converted to “salt shakers” that cruised the cold fresh water areas and salted them to increase their density and get them to sink.

      Forgot the name of the book, but it was an eco-novel, and the author included supplementary notes on the science involved—-it would be costly to mine, transport, and spread all that salt, but if and when the thermohaline SHTF it would appear to be affordable and doable.


  3. […] Big Story. The East Antarctic Ice sheet – the world's icebox, once thought all but impervious to melt on any meaningful time scale, is , on deeper inspection, much more vulnerable than we supposed….  […]


  4. There is ”permanent” ice thousands of miles north of Antarctic, in New Zealand and Patagonia.

    2] average temp on Antarctic is minus -35C; 35degrees below ice melting point – therefore: it needs the planet to warm up by extra 36C, for antarctic ice to melt from heat. It means: on the equatorial regions the temp would be above water boiling point!

    3] Antarctic and Greenland have enough coldness, to make another 50km thickness of ice in one season, only if there was enough ”raw material” for making ice (water vapor) On the polar caps, ice is not coming from snowing or rain; BUT, from freeze-drying the moisture from the incoming air: http://globalwarmingdenier.wordpress.com/midi-ice-age-can-be-avoided/

    • redskylite Says:

      The melt of the Antarctic Pine Island shelf is caused by warm circumpolar deep water that flows onto the continental shelf, surface temperature is not a measure of water currents. The shelf supports the glacier. There is much more at play than just surface temperatures. True climate change is largely driven by northern hemisphere events, but ocean currents circumnavigate the whole world, transporting heat and recycling carbon. I attach an interesting piece on the Pine Island melt:

      http://www.antarcticglaciers.org/glaciers-and-climate/shrinking-ice-shelves/pine-island-glacier/


      • redskylite, thanks for pointing me to that tread.

        2] I wish the same ”scientist” that believe that seawater can melt ice; to start realizing that: ”on Arctic ocean, the ice is constantly melted by the ”SALTY” seawater also – and the amount of ice depends on: how much raw material for renewal of the ice arrives from south in individual season, NOT ON AIR TEMP!!! Cheers!

    • dumboldguy Says:

      Take a look at Stefan’s blog, folks. It is spectacularly mind-boggling.

      The possibility exists that Stefan is spoofing the world with this whole climate change commenter bit, playing the English-impaired buffoon to see how many “fish” he can catch. He says also that he has written a BOOK with which to share his vast ignorance with the world, and complains that sales are not going well!!!! LMAO


      • Yiikes! Stefan the Denier’s blog is AWESOME, and proves that his comment is not a fluke. STD should at least get his arithmetic right. The record temperatures in the tropics are about 50 degrees C. 50+36=86 which is 14 degrees below water’s boiling point.

    • greenman3610 Says:

      I rarely trash comments, but almost trashed this one for the sheer stupidity.

      • dumboldguy Says:

        And you would have been 100% correct in doing so. We have seen some “stupidity” on Crock, but stefan is now the all time champ. That’s why I think he may be spoofing us—-NOBODY can be that ignorant of science.

  5. greenman3610 Says:

    test comment

    • dumboldguy Says:

      Grade = D. It came through but didn’t say much.


      • It didn’t say much because it was a test comment.

        • dumboldguy Says:

          Aren’t all “tests” graded?

          And aren’t students always asking “Is this going to be on the test?”


      • Now, I’ll retry my comment. 🙂

        Okay. This is fun. I agree that the 1984 article’s scenario is totally hypothetical. But let’s contemplate it – even if doing so is admittedly daveburtonish. (Considering your natural born combative personality – you are forgiven for that.)

        First of all, IMO, the mixing rate between the upper “mixed layer” and the deep ocean is too slow to be much of a factor relative to the time it would take our iceberg barrage to melt. The upper layer’s depth ranges between 10m and 200m. So let’s approximate an average depth of 100m to keep the arithmetic simple. 100 mm of added water would be 1/1000 of the total weight. Assume that the added ice is -10C and the water temp is 50C.

        The upper level temperature would fall by ((60+79.72)/1000) = .14 C

        Your turn. Woof.


      • And for some reason my totally friendly last reply to our earlier exchange still doesn’t get posted. The Blog God must want us to end our “debate”. 🙂


        • I calculated that if Sullivan’s scenario were to occur (I know that it’s no more than fictional horror movie material) that the ocean’s surface temp would temporally decrease by 0.14 C. And yes, this is a daveburtonish discussion.

          OK, let’s see if this works.

        • dumboldguy Says:

          Something goofy happened to this thread. The comment I made in response to you on May 5, 2014 at 9:39 pm didn’t appear for a couple of days. Have you seen it?

          Maybe that’s why Peter is sending “test messages”, in which case I will raise his grade to a B- (it’s still too short).


          • Yes. I did see it. Maybe you’ll see my full response in a few days DOG. Or it’s possible that there will be 15 copies that come through like a barrage of glaciers. Peter must have noticed a problem.


          • This is testing a software theory. Here is my original response with one edit.

            Okay. This is fun. I agree that the 1984 article’s scenario is totally hypothetical. But let’s contemplate it – even if doing so is admittedly the ish name omitted (Considering your natural born combative personality – you are forgiven for that.)

            First of all, IMO, the mixing rate between the upper “mixed layer” and the deep ocean is too slow to be much of a factor relative to the time it would take our iceberg barrage to melt. The upper layer’s depth ranges between 10m and 200m. So let’s approximate an average depth of 100m to keep the arithmetic simple. 100 mm of added water would be 1/1000 of the total weight. Assume that the added ice is -10C and the water temp is 50C.

            The upper level temperature would fall by ((60+79.72)/1000) = .14 C

            Your turn. Woof.

          • dumboldguy Says:

            COMBATIVE? Who are you calling COMBATIVE? &$&@**#%!!!
            I’m a sheep dog puppy—-you must mistake my friendly smile for an unfriendly show of teeth.

            Actually, the 1984 article is not “totally hypothetical”—it makes some sense, and has parallels in what we have just discovered about Antarctic ice sheets. But let’s DO contemplate it and try to leave the ish name out of it—–thinking of him turns my stomach.

            I started scribbling your math and parsing your logic, but quickly found myself confused again. As I do with these “puzzles”, I read this once, twice, and a third time and tried to wrap my head around it On the third reading, it hit me that you talked about a water temp of 50C and I put down my pencil, let my tongue hang way out and started panting to cool my DOG brain.

            50C = 122F, and that is WAY above the temperature at which proteins denature and nearly all living things in the water go the way of the boiled frog. I can’t get back to the physics and math until you give me numbers that don’t cook my DOGgy brain.

            An overheated Woof back atcha.


          • YES! Peter must have blocked the unnamed person to whom you compared my comment. WordPress even checks the text. Feel free to delete this debugging session Greenman.


          • Oh snap! How many old guys does it take to get it right? Answer: More than two.

            50 C was indeed stupid. I knew you’d catch me on something. Let’s try 18 C. To help with the numbers, the specific heat of water is 1 calorie per gram and it takes 79.72 calories to melt one gram of ice. The ice/water absorbs 28 degrees of heat plus the heat absorbed to melt it after it crashes into the ocean – or into a gin and tonic.

            (28+79.72)/1000 = .108 C


        • If the Sullivan scenario were to magically occur, the surface temp would fall by 0.14 C, temporarily. I deleted all details just to see if this posts. Into computer debugging more than “science” right now.


  6. […] 2014/05/05: PSinclair: New Research: East Antarctic at Risk of Unstoppable Melt […]


  7. […] 2014/05/05: PSinclair: New Research: East Antarctic at Risk of Unstoppable Melt […]


  8. […] will have negative contribution to sea levels over next 200 years – Published The CryosphereNew Research: East Antarctic at Risk of Unstoppable MeltNew Research: East Antarctic at Risk of Unstoppable MeltE. Antarctic ice […]


Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: