The Increasingly Fragile Pine Island Glacier Just Calved Again

The point where the Pine Island and Thwaites glaciers meet the sea serve as a back-stop restraining most of the great ice flows of West Antarctica. If those backstops were to fail, ocean water would flood inland along a reverse slope and generate a massive and swift out-rush of ice that would ultimately raise the world’s oceans by about 3 meters. And, lately, the evidence is mounting that the backstops are failing.

At Thwaites, just south of the neighboring Pine Island Glacier (PIG), recent research found that the ocean was flooding inland beneath that enormous ice sheet at a rate of up to 400 meters per year. But to the north, there is indication of trouble at the ice surface.

Back to Back Calving Events

Just last September, a massive 100 square mile ice berg calved off the Pine Island Glacier. The event was significant in that it marked the first major retreat of the glacial front in the face of an advancing ocean. Pine Island had already sped up. But the calving face withdrawal inland appeared to mark a new phase for the large glacier.

(Sentinel 1 satellite observations show a rapidly moving Pine Island Glacier calving off another large ice berg. Meanwhile, considerable damage appears to have been done to the glacial front.)

Now, just 7 months later, PIG is calving again. A large, approximately 6 kilometer long, 1 kilometer wide, chunk appears to have broken off into the Southern Ocean and shattered. Meanwhile, to the north and south along the glacial front, rifts appear to have formed.

This recent calving event is significant for a number of reasons. The first is that it’s happening just months after a recent large break-off during 2017. Other recent calving events at Pine Island occurred during 2001, 2007, and 2013. The present 2017-2018 events are back-to-back. The second reason is that the splintering appears to indicate a more fragile ice face. An impression reinforced by the concordant formation of rifts spreading away from the calving zone. The third is that the satellite imagery suggests Pine Island Glacier is moving quite rapidly (Recently, this rate of motion has been 1-2 km per year. However, it’s reasonable to question whether the glacier is continuing to speed up).

Conditions in Context

Present global warming due to fossil fuel burning has now forced the world into a range of temperatures between 1.0 and 1.21 degrees Celsius above 1880s averages. This boundary is similar to that of the lower range of the Eemian 120,000 years ago when oceans where 10-20 feet higher than they are today.

(The tall ice cliffs composing the Pine Island Glacial front have become increasingly fragile and fast moving as they enter the warming Southern Ocean and as that warming water continues to invade inland. Image source: Commons, Pine Island Glacier Calving Front, NASA.)

Under present greenhouse gas forcing and planned emissions, additional warming is in store. Climate models produced by Dr. Michael E Mann indicate that we are likely to hit the 1.5 C global temperature boundary some time between 2027 and 2031 on the current emissions pathway. This predicted warming is significant because analysis of past climates appears to indicate a risk of more rapid rates of sea level rise when global temperatures rise to a range between 1.5 to 2.5 C above past base line averages (see meltwater pulse 1 A).

Since the 1990s, the global rate of sea level rise has proceeded at roughly 3.3 mm per year with an apparent acceleration to around 3.6 to 4.1 mm per year during the 2010 to present time period. Given observed ice sheet instability in West Antarctica, in East Antartica, and in Greenland, there is a serious risk that this rate of rise will continue to accelerate over the coming years and decades. The key question of concern is how much and how soon.

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  1. Yesterday in a rural community in Ecuador, a lady and I watched the results of a medical test come in – that of a loved one who is not well. We exchanged silent and very-sober glances, as we knew what the results meant, and the others really didn’t know that it meant bad news ahead.

    This new calving reminds me of that kind of moment; it’s like seeing an x-ray of a blackened lung and knowing that the journey ahead will not be pretty… yet also knowing that many people prefer not to see the x-ray, or to ‘not know’ the facts – or even when they know the facts, keep smoking two packs a day…

    I appreciate all of the hard work and research you put into your posts, and writing at a level that even a novice can comprehend.

    Liked by 4 people

    • The PIG is certainly not well. We’re seeing something similar to what happened at Jackobshavn happen at PIG. But there don’t look like there is much in the way of breaking structures for this glacier as there is at Jackobshavn.

      Liked by 1 person

  2. Aren’t we already above 1.5 c ?


  3. In the Arctic, the Siberian times has updated its coverage of the exploding pingo phenomenon, claiming that Russian scientists have discovered a second methane blow-out occurring in the same crater:

    Crater formed by exploding pingo in Arctic erupts a second time from methane emissions

    “Startling new evidence from satellite images shows a repeat blast at one water-filled hole in tundra, say experts.

    A new theory also surmises that human exploitation of natural gas resources on the Yamal peninsula has led to the forming of toxic pockets which then explode, forming funnels or craters.

    The phenomenon of dramatically exploding pingos in Siberia’s polar regions has come to light only in recent years.

    It is being actively examined by scientists because of deep concerns over the safety of natural gas industrial installations including pipelines, as well as residential areas, for example on Yamal peninsula.

    A series of crater lakes – some tiny, others large and deep – have been caused by what has been seen as thawing permafrost leading to methane gathering under pingos – and then exploding.

    Today’s claims about second explosions in the same craters is entirely new.”


    • One of the worrisome things about this phenomenon is the number of small circular lakes in the Siberian topography. How many of these hundreds of thousands or millions of small circular lakes were caused by methane blow-outs?

      It seems to be possible to construct a plausible testable hypothesis in which relic methane hydrate is formed beneath ice sheets. This methane hydrate can persist in permafrost for tens of thousands of years in a “metastable” (meta-stable) state. Under global warming, this metastable methane hydrate may be dissociating, now, creating these methane blow-outs.

      Methane and CO2 could also be produced from rotting organic material in the permafrost.

      The hundreds of thousands or millions of small circular lakes in widespread areas of Siberia and small areas of North America could be the result of this methane blowout phenomenon, I think, possibly. There may have been a huge number of these blow-outs during the Holocene Climate Optimum of several thousand years ago. If so, this is a testable hypothesis- some of these blowouts should be subject to several thousand years of stream erosion from small streams or rivers in the area.

      One of the blow-outs was directly under a river, in Siberia. This may be due to heat from the river producing a talik – an unfrozen area in the permafrost.


    • Carbon feedback is a serious concern for the Arctic. However, we should not ignore the primary source of the warming that is producing that feedback: fossil fuel burning. The article above appears to do just that.

      It appears that the region is likely to produce a feedback forcing between 10 percent and 30 percent compared to the present human emission over the course of this Century. Presently, though local sources of methane and carbon dioxide feedback are proliferating, the signal has not yet been resolved as a major one on a global scale. That said, it does appear that the Arctic baseline is moving.

      Overall, though, I think we should be less concerned about the gas infrastructure and more concerned about keeping carbon of all kinds in the ground. And we should also be clear that the methane issue is continuously misused as an excuse to generate either apathy or to support harmful responses (solar radiation management).

      Due to Russian manipulation of U.S. media and elections, I also consider sources from that country to be suspect and aimed at generating divisive or misleading messages. This may or may not be the case with regards to the recent ST articles. However, the methane issue has been misused in the past before. And I don’t see much difference in the present messaging that oddly supports the mass carbon emitting gas industry in the face of the ramping climate change it has, in large part, caused.


      • Hi Robert-

        The Russian scientists are mentioning a possible link between the exploding pingos and what they call “technogenic” causes – that the craters may be associated with natural gas production. The news reports said something about “toxic pools” of methane associated with natural gas production, whatever that means.

        I think myself that it is a natural phenomenon, but one that has scary long term implications for carbon feedback as the rate of formation of these things accelerates under global warming. If most of the small lakes in that region are due to these methane explosion craters, that progressively enlarge themselves due to the edges falling into the crater and sometimes merge together into larger lakes, these things could start popping like popcorn, I think.

        Present methane emissions from this source are likely not significant. But measured concentrations of methane at the bottom of one of these craters was 9 percent – equal to 45,000 times the methane concentration in the open air. Now it’s looking like these craters can erupt multiple times, and be chronic sources of emissions over a long period of time.

        How much methane would have to be leaking constantly to maintain a methane concentration 45,000 times that of the open air in the bottom of a crater? What are the chronic emissions from these things, and what are the chronic emissions from the piingos that just bulge and don’t explode?

        I really don’t worry about what effect the truth might have on peoples’ attitudes or on the fight against global warming. I just think we ought to tell the truth, and hope that the feedback from telling the truth will help us all react more appropriately.


        • The best studies that I’m able to find indicate a 10 to 30 percent carbon feedback coming from the Arctic under present warming scenarios. This is our present best understanding of the truth. I’ve reported on it many times.


      • I should say that this methane crater phenomenon is a natural response to human caused global warming, just to be clear. So, it’s natural in the sense that it appears to have happened before, if hundreds of thousand or millions of lakes in those areas are remnants of past craters.

        But this methane crater phenomenon is distinctly unnatural in the sense that it’s being triggered, apparently, by hugely accelerated unnatural global warming primarily due to fossil fuel use.


    • rhymeswithgoalie

       /  April 11, 2018

      Wouldn’t seismographs notice the large ones?


      • Yes, they are building a network of seismic sensors, and using satellite imagery to find the expanding pingos.

        They have located something like 7000 pingos whose shape is changing, I think, and most or all of the Russian scientists say there could be many more.


  4. Matt

     /  April 11, 2018

    On a different note…
    It seems the Negative stage of the ENSO cycle is soon to be over, La Nina stage is already over and now in Neutral. How long before we get to El Nino and more importantly…. how strong will it be?


  1. Present global warming due to fossil fuel burning has now forced the world into a range of temperatures between 1.0 and 1.21 degrees Celsius above 1880s averages. This boundary is similar to that of the lower range of the Eemian 120,000 years ago when
  2. Present global warming due to fossil fuel burning has now forced the world into a range of temperatures between 1.0 and 1.21 degrees Celsius above 1880s averages. This boundary is similar to that of the lower range of the Eemian 120,000 years ago when
  3. Extreme Temperature Diary-April 10, 2018/ Topic: How Much Warming is Forecast for the 2020s? – Guy On Climate

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