Bleak Views of Melting Antarctic Ice, From Above and Below

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Yves here. With so much drama on so many fronts, we’ve been relegating most climate change news to Links. We thought we should counter that with some overdue reporting on ice melt and sea level rises.

By Karin Kirk. Originally published at Yale Climate Connections

The calving front of Thwaites Ice Shelf looking at the ice below the water’s surface as seen from the NASA DC-8 on Oct. 16, 2012 (Photo credit: James Yungel, NASA).

Images from satellites high above the Earth have helped a research team put together a stark visual chronicle of decades of glacier disintegration in Antarctica. Meanwhile, a separate international research team has taken the opposite perspective – studying the ice from its underbelly. Both teams are documenting the stress on two glaciers in West Antarctica that so far have helped check a massive stream of melting ice responsible for about 5 percent of Earth’s rising sea levels.

Climate researchers have long monitored ice sheet dynamics in the Amundsen Sea, focusing specifically on the Thwaites and Pine Island glaciers. The two sit side by side on Antarctica’s western peninsula covering an area roughly the size of nine U.S. coastal states stretching from Maine to Maryland. The two glaciers alone store ice that could account for about 4 feet (1.2 meters) of global sea level rise. Their “seaboard” location may help bring increased public attention and interest to the West Antarctic Ice Sheet, which if it melted could raise seas by a catastrophic 11 feet (3.4 meters).

An international effort led by the British Antarctic Survey recently published two papers (Hogan et al. and Jordan et al.) showing the first detailed maps of the seafloor at the edge of the Thwaites Glacier. The team mapped deep submarine channels that have been funneling warm water to this vulnerable location. High-resolution imagery pinpoints the pathways that allow warm water to undermine the ice shelf. Lead author Kelly Hogan of the British Antarctic Survey says the findings will improve estimates of sea-level rise from Thwaites Glacier. “We can go ahead and make those calculations about how much warm water can get under the ice and melt it,” Hogan said.

The other researchers, led by Stef Lhermitte, found stark visual confirmation of glacier disintegration using decades of time-lapse satellite imagery. Their work sheds light on the accelerating feedback process, wherein the rapid loss of ice is opening the door to ever-increasing melting.

Melting from Below

Snowfall on the inland portions of Antarctica feeds the Thwaites and Pine Island glaciers, which flow downhill and out into the Amundsen Sea. The glaciers extend beyond the coastline, and the base of the ice rests on the seafloor. In front of the grounded ice, a floating shelf of ice stretches out into the ocean. These marine ice sheets are particularly sensitive to changes in climate, and rapid changes in these vast glaciers are making this the world’s largest zone of uncertainty for projections of sea-level rise.

Floating ice shelves have long protected and stabilized the glaciers behind them, slowing the flow of ice into the sea. But when the protective ice shelf is lost, the stream of ice it had held in place becomes free to drain to the sea. Such changes have occurred in West Antarctica in the geologic past, unlocking enormous volumes of ice during periods of climatic warming.

Hogan’s team studied the warm, salty current called the Circumpolar Deep Water, which follows undersea channels directly to the front of the Thwaites Glacier. This process is “thought to be one of the major culprits for melting at Thwaites,” Hogan said in a recent radio interview. To compile this data, the team undertook a two-month journey aboard the Nathaniel B. Palmer, a 300-foot icebreaker specially equipped for scientific research.

The scientists found seafloor channels to be more than 2,600 feet (800 meters) deep, several hundred meters deeper than originally thought. As a result, the amount of warm water that can reach the ice front is also larger than previously believed, with more warm ocean waters able to erode the ice shelf from the bottom up.

Thus, the accelerated feedback process: First, the floating portion of the ice shelf thins, cracks, and breaks apart. Also, the “grounding line” where the ice rests on the sea floor retreats landward. Since the grounding line anchors the ice sheet, its retreat is like kicking the chair out from under a seated person. As the grounding line moves landward, the ice shelf is destabilized. Large slabs of ice can detach, or “calve” into the open sea. Warm ocean water gains access to new areas of ice, fueling more melting.

Ice Breakup Visible from Above

Another study released earlier in September shows the visible effects of a warming climate on the Thwaites and Pine Island Glaciers, using time-lapse satellite imagery dating back to 1973. The images show the ice weakening, thinning, retreating, and breaking apart, evidence of a decline in the ice shelves that could possibly lead to wholesale collapse.

Videos provide compelling time-capsule images of thinning and breaking apart of Antarctic glaciers.

This series of images shows the ice front at Pine Island Glacier in a more or less stable position from 1973 to 2014, and then a startling retreat in 2015 through the present. Roughly 30% of the ice shelf disappeared over the past six years.

These time-lapse photos Movie S5 from Thwaites Glacier span a 20-year transition from an ice surface that was smooth and solid to one that became fractured and crevassed as it ripped apart.

In this video Movie S3 the ice shelf that had been holding Thwaites Glacier in place has been reduced to “melange,” a fluid mixture of ice fragments. These remnants of the formerly solid ice offer none of the buttressing effect of a solid ice shelf.

The research team documented other effects too: the glaciers and their ice shelves are thinning, and the speed of glacial outflow has increased. Both of these processes contribute directly to rising seas.

Concern over ‘Further Disintegration’ of Glaciers

The observed changes to these glaciers are worrisome enough, but the authors are especially troubled by signs that the decline is speeding up. Lhermitte and his co-authors posit that the types of damage they documented are signs that “these ice shelves are already preconditioned for further disintegration.”

The region may have passed a tipping point because damage to the ice paves the way for further breakup. For example, cracks in the ice surface cause structural damage that can trigger large-scale calving events. In turn, the calving causes further weakening when adjacent ice streams no longer connect to each other, making each one less stable.

Similarly, when warm water melts ice from below, the ice shelf loses contact with the seafloor that holds it in place. The detachment from “pinning points” can allow the ice to speed up, which then allows more cracks and troughs to form, exacerbating the instability.

Taken together, the research paints a picture of an accelerating decline of ice. Such feedbacks intensify the scale and pace of change, and are difficult to predict. Scientists have concluded that major ice loss in this region appears to be irreversible.

Stunning Visuals

A set of visualizations called Mass loss in Antarctica documents the declining ice. On NASA’s Earth Observatory website, readers can drag a slider across images from 2001 and 2019 to watch the decline of Thwaites Glacier over time. Major calving events from the ice shelf at Pine Island Glacier are captured in a series of NASA images.

Consequences for Coastlines

Projections of sea-level rise by research entities like the IPCC are often conservative, pinning hopes on a middle-of-the-road scale of consequences. But scientists note that more dire outcomes are possible, especially as amplifying feedback effects kick in. Climatologists have long viewed the West Antarctic Ice Sheet as a likely place for such an outlier event.

This current work helps clarify the exact processes leading to ice loss and documents the pace of change. The results, while unsettling, will also lead to better estimates of what’s in store for the world’s coastlines. Even if the news is bad, it’s far better to be forewarned than to be caught off guard.

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25 comments

  1. Moe Knows

    Indeed all true. The way of world, always changing. Water wears down the rock, and water wears dow the ice. How could it be otherwise.

    Reply
    1. a different chris

      Yeah I built a pond and put rocks along the edges and 5 years later all the rocks were worn away.

      Lordy these people.

      Reply
    2. Larry Gilman

      Hi Moe. It’s true that everything is always changing to some extent, including glaciers and seas and rocks, but it doesn’t follow that all changes are natural or benign, any more than the fact that we must all die someday means there’s no such thing as murder. Whether Antarctica is a climatic crime scene or not has to be decided from evidence, not generalities about the impermanence of all things. And the evidence is clear: like hundreds of other changes around the world, these dangerous accelerations of melting are human-caused.

      Reply
    3. Wukchumni

      I grew up on Time-Life books, my mom never saw a series of them she didn’t like, and it made a good adjunct to the World Book encyclopedia, in that I could go more in depth on a host of subjects in a banquet for the brain.

      So, a few years ago @ our thrift store in town, there’s 6 of them from 1983 for a buck a piece, and I scoop em up and make off with my bounty, and one of them is “Ice Ages” and in it, they postulate that the West Antarctic ice sheet might start breaking off-with worldwide flooding circumstances, in 200 years.

      Whoops, we got there in 1/6th of the expected time…

      Reply
  2. shinola

    “Even if the news is bad, it’s far better to be forewarned than to be caught off guard.”

    What about forewarned but ignored?

    Reply
    1. drumlin woodchuckles

      Those who accept reality can facilitate the migration of themselves and all their fellow reality-accepters away from the coasts.

      Those who accept reality should figure out how to get those who deny reality to buy coastal seaside beachfront property.

      I would like to see a borderline upper-class person who is skilled in the arts of Financialist Warfare and Dollar-to-Dollar Combat set up an investable-in fund of some kind. Mutual, hedge, something else? I don’t know about funds. But I would like to see a Just Deserts Eco-Warrior with Financialist Warfare skills set up such a fund, make it fully legitimate within the law, have it properly audited and accounted and etc., and invest the money from fund-share-buyers in coastal future-flooded businesses which WOULD be honest and viable if there were no Global Warming. That would bullet-proof the fund against
      charges of fraud and etc.

      Once such a fund was set up, it could be called the Climate Sceptic Fund. It could sell itself as offering a chance to invest in things which will prove to be of lasting value and profit if Global Warming is the Hoax that the Sceptics say it is. It would be a chance for every Global Warming Denier to inVEST in his/her Denialism.

      No, I am not being satirical. No, I am not being sarcastic. Yes, if I had that very special skillset I would in all honest reality set up such a fund myself. I would break no laws. I would with a very straight face help everyone who deserves to be on the iceberg . . . pay to buy a space on the iceberg. And then blame no one but themselves when their investments all go “underwater”.

      Har Dee Har Har.

      Reply
    1. Anynomous

      Not a thing. Geoengineering is just wishful thinking at this stage. The truth is, ecosystems are complex systems, in effect unpredictable. Every time we’ve tried anything like this, we’ve made things worse. It frustrates me and scares the heck out of me when I see people putting their hopes of solving climate change on technology. I’m an engineer, the technology to solve climate change does not exist and it will not exist in decades or centuries, if ever. It’s all fantasy, science-fiction at best. The way things are, we need to change our lifestyles and socio-economic systems, at a global scale, and quick. There’s nothing we can build today that will do it for us. And understand this, the consequences of what we’ve done already, even in the best case scenario (where everyone agrees next week to do what’s necessary and we get on with it the week after), will be felt for decades: collapsing ecosystems, mass migration, extreme weather effects, wars…

      Reply
      1. ambrit

        As you say, our life styles etc. will now be changed for us by the ecosystem. We are about to come face to face with direct evidence of the bankruptcy of the Cult of Technology.

        Reply
      1. Yik Wong

        +1000

        Trying to bottle up unstable Carbon (Dioxide) to reverse the 100+ years of geo-engineering by burning geo-stable carbon, ie: Hydrocarbons.

        Reply
    2. drumlin woodchuckles

      Sure. Then we can keep right on burning fossil fuel under a cooling screen of sulfuric acid micro-droplets in the tropopause.

      All life in the sea will die from ongoing Ocean Acidation due to the ongoing Carbon Skyflooding. But at least we won’t be uncomfortably hot while we all starve to death. And smother to death once all the atmospheric oxygen is depleted.

      So, yes. The time has come for geo-engineering.

      ( This was in response to the “is it time for geo-engineering?” comment, which did not/ will not nest properly)

      Reply
      1. Jeremy Grimm

        I believe you are referring to the SPICE program. That program died:
        [https://www.nature.com/news/geoengineering-experiment-cancelled-amid-patent-row-1.10645]
        Geoengineering experiment cancelled amid patent row
        Balloon-based ‘test bed’ for climate-change mitigation abandoned.
        Daniel Cressey 15 May 2012
        I suppose some other group might pick up the idea later and use sulfuric acid micro-droplets.

        Reply
    3. Jeremy Grimm

      There is a an hour long lecture on youtube that explains why geoengineering is not such a great idea: “Prof. Philip Mirowski keynote for ‘Life and Debt’ conference”: [https://www.youtube.com/watch?v=I7ewn29w-9I]
      I grabbed two slides near the end of this lecture that summarize why geoengineering is not a great idea. Much of the earlier portions of the lecture are devoted to explaining how geoengineering relates to a Neoliberal plan for continuing to burn fossil fuels as long as possible, while also profiting from those schemes.

      slide at minute 46:43
      Ultimate Long-term fix: [3] Geoengineering by Private Firms to Further Alter Climate
      – This version makes pact with NL[Neoliberal] scientists to produce the venture cap entrepreneurial ‘solutions’ to previous market-induced environmental degradation
      – Include: Earth albedo enhancement (reflective particles, space mirrors), CO2 sequestration (ocean seeding, fracking storage), direct weather modification (cloud seeding)
      – Appeals to sci-fi belief that technology will save us, after putting us at risk

      slide at minute 53:45
      Neoliberal contempt for serious prudential concerns
      [Geoengineering]
      – Cannot be tested ahead of time
      – Involves unilateral actions in violation of scads of international treaties.
      – Imagines few corporations hold entire globe hostage for short-term profit
      – Don’t actually address root causes, but rather attempt short-tem expedients to get around CO2 emissions continuing unabated.

      Mirowski uses the SPICE project as an example geoengineering program:
      https://www.nature.com/news/geoengineering-experiment-cancelled-amid-patent-row-1.10645

      Geoengineering experiment cancelled amid patent row
      Balloon-based ‘test bed’ for climate-change mitigation abandoned.
      Daniel Cressey 15 May 2012

      More recently Bill Gates is working with Harvard funding the “Stratospheric Controlled Perturbation Experiment (SCoPEx), will spend $3 million to test their models by launching a steerable balloon in the southwest US 20 kilometers into the stratosphere. Once the balloon is in place, it will release small particles of calcium carbonate. Plans are in place to begin the launch as early as the spring of 2019.”
      [https://www.forbes.com/sites/trevornace/2018/12/05/harvard-scientists-begin-experiment-to-block-out-the-sun/#756f78c40c24]
      [https://projects.iq.harvard.edu/keutschgroup/scopex]

      Reply
  3. Jermy Grimm

    Besides the rise in sea levels the increasingly rapid melting at both poles and in Greenland presents other issues. “New studies confirm weakening of the Gulf Stream circulation (AMOC)” — stefan @ 17 September 2020
    [http://www.realclimate.org/index.php/archives/2020/09/new-studies-confirm-weakening-of-the-gulf-stream-circulation-amoc]

    Though the disasters in “The Day After Tomorrow” are way over-the-top a slowing AMOC further increases the sea level off the East coast the of the U.S. and adds a little chaos to the transition to our new climate.

    Reply
  4. Wukchumni

    Not all places with harbors will work, but there must be a good amount of locations where you could build replacement harbors somewhat inland and higher up in order to be ready for inundation. As far as I know, nobody is doing this.

    Reply
  5. Synoia

    I believe that sea level rise will be greatest at the equator.

    Sea level ————————-/\——————————
    Hawaii ………………………./ \……………………………..

    Reply
  6. ocop

    If you are interested in keeping up with the emerging science of Antarctic ice melt related subjects and or nerding out on a new topic there are a few devoted (obsessive?) posters who summarize research articles for a slightly more general audience in a polar ice web forum here: https://forum.arctic-sea-ice.net/index.php/board,13.0.html.

    Over my skis a little, but the general take away is that current scientific consensus projections of sea level rise are underdone owing to the inability of many models to account for the physical dynamics of ice shelves (ice cliff and ice shelf instability) and positive feedback loops.

    Reply
    1. drumlin woodchuckles

      Are such projections also undone by liquid water pooling on top of ice sheets and caps, absorbing more sunlight and heating up more right there in place than reflective ice would have done, and then melting down to the bottom of the ice cap, thereby lubricating its contact with the rock it was frozen onto? Thereby allowing huge chunks of it to break up and slide downslope?

      Reply
  7. Anonymous

    Otoh, think of all the new homesteading opportunities in Siberia, Greenland and Antarctica?

    Snark aside, if we are not willing to deal with the root of the problem, which is a government-privileged usury cartel, then what sympathy do we deserve for the unpleasant branches?

    Can’t cheat an honest man?

    Reply
  8. Hugh Martin

    You can check ( graphically ) the extent of Antarctic sea Ice extent and recent changes here .

    As you can see Arctic Sea Ice extent is low but Antarctica is on the high side of normal .

    While there has been genuine sea ice decline in the Arctic there is none in the Antarctic .

    Antarctic Sea Ice extent was quite normal until about 2016 when it took a big hit from the
    El Nino event , since then it has returned to normal .

    You can also check Antarctic temperature history here ( at Casey Station ) and see for yourself there has been no detectable increase .

    ..

    Reply

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