Some guy said it was, so there

The idea of ice sheets slowly melting and concomitant gradual sea level rise is not very frightening. The satellites suggest that the rate is accelerating, but the onshore gauges shrug their shoulders. Neither the accelerating rate of rise reported by the satellites nor the slow and steady creep reported by the gauges are anything for modern civilisation to fear.

But.

What if I could suddenly trump that unexciting slow rise with something that would get Cnut scampering off the beach? Or at least, the threat of a sudden rise soon, let’s say by 2030? What if an entire glacier might slide off Antarctica like a kid on a toboggan and add, let’s say, half a metre to present sea level? Are you scared yet? Why not, dammit?

I think we should call this glacier the Doomsday Glacier, just in case anybody is still refusing to wet their bed about it. It does have an ordinary name too: Thwaites Glacier.

Fans of DC Comics will know that there is a supervillain in that fictional universe who is also called Doomsday. (You will also have fleetingly glimpsed him in the movie Batman v Superman: Dawn of Justice if you put yourself through that ordeal.) Doomsday has a very special power, which aficionados will know about but casual viewers of the recent film will not have picked up on. More on that in a moment. First let us focus on our real (harrumph) Doomsday.

As an aside, let me just say that the idea of advancing ice sheets has always seemed more frightening to me than retreating ice sheets. I suppose it depends where they are: if the ice sheet is near where you live, you would prefer it to roll back. If it is far away, and you live let’s say within a metre of Mean High Water Springs, then you’d probably prefer to hear that the ice is rolling forwards. Not too fast though, because if it’s rolling forwards too fast it might slide off altogether.

Intermission: a selection box of headlines

Warmer oceans driving Antarctic Peninsula glacier melt, study says

New study reveals glaciers are rapidly melting

The East Antarctic glacier that has shrunk by 5 kilometres in 22 years

Glaciers in part of Antarctic thought to be stable suddenly melting at a massive rate say scientists

West Antarctic ice melt is now ‘unstoppable’

Anyway, Thwaites. Now that you’re trembling, tremble some more, mortals, etc. Thwaites is scary because some time ago some scientists found that the floating bit of the ice sheet is perched on a ridge. The ridge – oh heck, let’s hear how the scientists themselves describe it:

Lamont-Doherty geophysicist Robin Bell, study co-author, compares the ridge in front of Thwaites to a person standing in a doorway, holding back a crowd. “Knowing the ridge is there lets us understand why the wide ice tongue that used to be in front of the glacier has broken up,” she said. “We can now predict when the last bit of floating ice will lift off the ridge. We expect more ice will come streaming out of the Thwaites Glacier when this happens.”

Columbia.edu
Tinto & Bell (2011) figure 1c

The figure from Tinto & Bell shows the profile of Thwaites. The long nose is the ice shelf that is no longer in touch with the ridge. When did it lift clear? Some time between 1861 and 1956. Not, you might think, something to do with our emissions of CO2, etc:

At these rates, floating ice could have been grounded across the offshore ridge between 55 and 150 years ago.

Tinto & Bell 2011, paragraph 24

With the nose clear of the ridge, and the couple of peaks that remain to pin it, Thwaites will flow faster. Too, the water seeping in from the ocean will be able to trickle down under the glacier, lubricating it so that it flows still faster. So the story goes.

Of course the excitement around Thwaites did not actually begin in 2011. It began around 1973 with Terry Hughes’ article “Is the West Antarctic ice sheet disintegrating?” According to a computer realisation of Hughes’ mathematical model (1981):

Future collapse of the West Antarctic ice sheet resulted from present surges of Thwaites and Pine Island Glaciers and was complete in only 200 years.

Hughes 1981

Eric Rignot revisited the peril at the turn of the millennium. Thwaites was flowing faster, and in consequence, getting thinner. In fact you might as well say that ever since anybody looked at Thwaites in any detail, terror has abounded. But there is no doubt that as attention has grown, so has the peril. Perhaps there is too much science these days. In any case Antarctic scientists on Thwaites are now like wasps on jam.

Some wasps intoxicated by National Trust jam

Here are the search returns by decade (actually 11 year bins, since both start and end years end in 0s) for “Thwaites Glacier” (string in quotes) on Google Scholar.

Time PeriodHits in Google Scholar
1970-198018
1980-199050
1990-200078
2000-2010362
2010-20201940

These days there are enough glaciologists rolling around on Thwaites drunk on sugar that in the proper season it’s hard not to trip over them. (This is a lie, or at least a gross exaggeration.) Even journalists get to visit in order to (a cynic might think) raise the profile of the terror still more to keep the funding flowing. So it was that in the southern summer of 2019/20, the BBC’s intrepid Justin Rowlatt went on his own adventure to Thwaites.

Antarctica melting: Climate change and the journey to the ‘doomsday glacier’

Icefin [a submersible robot] has reached the point at which the warm ocean water meets the wall of ice at the front of the mighty Thwaites glacier – the point where this vast body of ice begins to melt.

In discussions of Thwaites Glacier, we often hear the phrase “warm water.” This conjures up an image of something Caribbean. Not something that would kill you in under a minute. How warm is warm?

“The deep Antarctic circumpolar water is only a handful of degrees warmer than the water above it – a degree or two above 0C – but that’s warm enough to light this glacier up,” says David Holland, an oceanographer with New York University and one of the lead scientists at the grounding zone camp.

So that’s salty water at 2 degrees. The glacier is composed of fresh water and melts at 0. A blowtorch it ain’t.

The scientists say the Pacific Ocean is warming up and that is shifting wind patterns off the coast of West Antarctica, allowing the warm deep water to well up over the continental shelf.

Rowlatt’s BBC article blames the thermohaline circulation. We all know that there’s a transport of heat from warm regions of the Atlantic up north, which keeps the UK at a nice temperature, usually not too hot, and only rarely too cold (compare other places around the world at similar latitudes). The returning water does not, however, go directly to Thwaites. Instead it joins the circumpolar current that flows eastward. Thwaites is at about 105 W, which is opposite Baja California, not the Fram Strait. In fact the bit of the Antarctic opposite Greenwich is the Fimbul Ice Shelf. (Fimbulwinter, you might remember, is the three years of winter that heralds Ragnarok in Norse mythology.)

Anyway the key to the circumpolar current is the Drake Passage, without which there wouldn’t be a circumpolar current. Once the strait opened, Antarctica became isolated from the flow of heat from warmer climes, and a massive expansion of the ice sheet was initiated.

Thus you might be forgiven for thinking that a slowing of the circumpolar current would lead to melting ice in the Antarctic. However, a speeding up of the circumpolar current also leads to melting ice in the Antarctic. Perhaps we are in the Goldilocks zone at the moment: not too fast, and not too slow. (In fact it is said to be that the eddies in the current become more pronounced when the current speeds up: see image below – Thwaites is at about 9 o’clock.)

The ACC by an EU satellite from the Indy via MSN

There’s been a sudden flurry of Thwaites news recently. More or less anytime a bunch of scientists go to Thwaites, they come back with new data telling everyone to be more afraid than we were before. Surely one day they will come back and say “actually, it’s not as bad as we thought.”

The latest terror is that of the windshield crack’d. Science:

The most dramatic sign of impending failure is a set of diagonal fractures that nearly span the entire shelf. Last month, satellites spotted accelerating movement of ice along the fractures, says Erin Pettit, a glaciologist at Oregon State University, Corvallis, who is part of a multiyear expedition studying the glacier. The shelf is a bit like a windshield with a series of slowly opening cracks, she says. “You’re like, I should get a new windshield. And one day, bang—there are a million other cracks there.”

Science

[Sometimes I catch myself abusing the word “like” as well. I must not judge.]

How much is being spent on this multiyear expedition? Glad you asked. “…more than $50 million…”

Once the ice shelf shatters, large sections of the glacier now restrained by it are likely to speed up, says Ted Scambos, a glaciologist at the University of Colorado, Boulder, and a leader of the Thwaites expedition.

Ibid.

In 2008 Scambos predicted that the Arctic Ocean would be ice free in summer by 2013. [So far, history records that it wasn’t.]

Oh, the title of the Science piece, dated 13 December 2021, is:

Ice shelf holding back keystone Antarctic glacier within years of failure

I like the word “keystone.” It is suggestive of an actual keystone, which when removed from the heart of a structure, causes the collapse of the whole.

Now, where did the name come from? Who had the audacity to christen this inert lump of ice, which has hitherto harmed no-one, and whose threats are seemingly speculative, the “Doomsday Glacier”? Why not call it something nice, like “Mr Tiddles”? For the answer to that, we have to look to Rolling Stone, and its contributor Jeff Goodell:

Rolling Stone

That’s why, when I wrote my 2017 Rolling Stone story about Thwaites, I dubbed it “The Doomsday Glacier.” (The name stuck — if you type the phrase into Google now, you get half a million hits.)

Ibid.

Great, thanks professor – we’ll take it from here. (By the way, Goodell also had the opportunity to trip to Thwaites, in 2019.)

The Rolling Stone article that quote was taken from has arguably jumped the shark, or whatever the appropriate equivalent is for colder climes. Picked up the penguin, perhaps. I mean, it’s only coming for those of us who live within half a metre of Mean High Water Springs, right? Folks like me who live at about 30 metres above sea level can still afford to snark about it.

Conclusion

I am very doubtful that anything bad will happen thanks to Thwaites in the near future, or by 2100 for that matter. The suggestion that any sea level rise due to Thwaites would be beyond what modern civilisation could cope with easily is absurd. (This may be argument from incredulity, so feel free to correct me.)

Now, to return to the real Doomsday, the real fictional Doomsday that is. His special supervillainous power was that, while he could be killed, he always came back to life. And every time he came back to life, he was immune to everything that had already killed him up to that point. Doomsday: a perennial favourite, and every time he comes back, it’s a definite case of “It’s worse than we thought.”

This is a shot from NASA’s Terra satellite taken on March 10 2021. The ice shelf is moving roughly towards the south west with the image as the reference frame. The position of the shelf in about 2010 is outlined in faint grey, & the considered “grounding line”, or “coastline”, at that date is in a darker grey. Oh yeh: the smooth ice is frozen sea water, the lumpy stuff is the shelf, some bits of which will have broken free previously.

References

The literature is available via Google Scholar as pdfs.

Hughes, T. J. (1981). The weak underbelly of the West Antarctic ice sheet. Journal of Glaciology27(97), 518-525.

Rignot, E. (2001). Evidence for rapid retreat and mass loss of Thwaites Glacier, West Antarctica. Journal of Glaciology47(157), 213-222.

Tinto, K. J., & Bell, R. E. (2011). Progressive unpinning of Thwaites Glacier from newly identified offshore ridge: Constraints from aerogravity. Geophysical Research Letters38(20).

24 Comments

  1. We all know about isostasy especially regarding depression of the earth’s crust by the weight of glaciers, but does anyone know whether isostatic effects have been taken into account with projected sea level rise? It seems to me me that with all that extra weight of water, there would be some depression of the earth’s crust below the oceans. Could it be significant?

    Like

  2. Jit, thanks for the digging. Those statistics on “the search returns by decade (actually 11 year bins, since both start and end years end in 0s) for “Thwaites Glacier” (string in quotes) on Google Scholar” are astonishing, though I suppose they shouldn’t surprise us.

    As for “How much is being spent on this multiyear expedition? Glad you asked. “…more than $50 million…”” Good grief. Who’s paying?

    Liked by 1 person

  3. Mark, according to Science:

    Exploring the future of this keystone of the West Antarctic Ice Sheet is the aim of the International Thwaites Glacier Collaboration (ITGC), a multiyear, more than $50 million expedition funded by the United States and United Kingdom.

    Joe, I will look into the volcanoes. I suppose the question is whether they have become more active, which is probably difficult to tell. Knowing the rate of retreat of a glacier can give you an estimate of when it was last at a certain place (as in grounded on a ridge as Thwaites was).

    Potentilla, I’ve never thought about it, but I presume that if you push down hard somewhere, somewhere else will pop up. Something I thought about years ago but never looked into was what volume of oil had been removed from continental shelves and how much that might have lowered the level of the sea floor if at all. No doubt Alan will explain if he read this.

    Liked by 1 person

  4. ps – the relevant quote at the end – ”
    I think the evidence that the current retreat of Antarctic glaciers is owing to anthropogenic global warming is weak. The literature is mixed on this, about 50% of experts agree with me on this. So you’ll get no argument from me there. Second, the localization in West Antarctica is well understood, and I’ve written about it extensively.

    Elsewhere, Steig has attributed the West Antarctic glacier retreat to erosion of the grounding line of the glaciers by relatively warm Circumpolar Water, rather than to very slight warming of air temperatures above West Antarctica. Given the continuous retreat of West Antarctic grounding lines over the Holocene, it seems implausible to attribute present grounding line erosion to a different cause than past grounding line erosion that has taken place over the Holocene. Steig’s position on this point seems entirely reasonable.

    However, it still seems like one of those too typical situations where the less alarming explanation is presented in specialist literature, but left unmentioned or unconfronted when retreat of West Antarctic glaciers is presented as a cause of alarm.

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  5. Hunter, Re climateaudit: “However, it still seems like one of those too typical situations where the less alarming explanation is presented in specialist literature, but left unmentioned or unconfronted when retreat of West Antarctic glaciers is presented as a cause of alarm.”

    I recall reading this at the time. Thousands of such omissions made over decades, makes for a huge wall of bias towards the catastrophic.

    Like

  6. Dougie, you went into spam along with the usual hundred comments like

    “Have you tried exploding mind vape juice?”

    [I made that one up.]

    As to why, I don’t know – perhaps a link to CA annoyed WP, but it let the link through a second time. I’ll leave the comment in the twilight zone since you’ve pasted in the quote again and got the link through.

    I think the perspective of the Holocene is an important one. Because these ice shelves were only mapped recently (air forces with nothing to do after WW2 presumably), and because only now are detailed measurements being taken, only now do we realise that Thwaites is in reverse gear. We know it has been going backwards for a while – why not thousands of years? (Although to be fair, there are limits to how far ice masses could accumulate around Antarctica, so a linear retreat on that timescale would perhaps not be plausible).

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  7. Enter a redundant geologist.

    1, volcanicity in West Antarctica. This should not be thought of in terms of eruptions but more about the underlying cause of volcanoes, namely buried bodies of magma signifying a steeper geothermal gradient. It is this warmer than usual rock surface temperature that causes basal glacial melting and lubrication of the base of glaciers. If this were a possibility beneath the Thwaites Glacier I would have thought geophysicists would have established this by now, given the intensity of interest.

    2.Removal of oil from continental shelves and effect on sea level. It depends, but I suspect it always will have minimal effects. With the exception of shelves that are sites of major river deltas (which include some prolific hydrocarbon accumulation, like the Gulf of Mexico) the rocks in most continental shelves withstand overburden pressures by a combination of rock strength and fluid pressure within the rock porosity. If fluid pressure is reduced by extraction of hydrocarbons this will be countered by lateral flow from surrounding rocks. Since the volume of fluids is so very large the drop in pressure there is very small and unlikely to cause any perceptible effects. This maintenance of pressure in hydrocarbon reservoirs constitutes the first mechanism that drives hydrocarbon extraction (= Primary production). On shelves where sediments (especially fine grained, with low permeabilities) accumulate rapidly, conditions are very different. The low permeabilities of sediments cause overpressures to develop within them, which can be the energy used in primary hydrocarbon extraction but this is small relative to that in “normal” shelves. Once this is exhausted extraction must be by artificial means (water flooding and the like), or most of the hydrocarbons are left in the ground. The wholesale development of overpressure can make the entire sediment pile unstable. Many shelves are and were afflicted by major downslope sediment movements and the sediment pile is cut by huge curved (=listric) faults along which such sediment slips occurred.
    I could go on…but…..

    Liked by 3 people

  8. “We all know about isostasy especially regarding depression of the earth’s crust by the weight of glaciers, but does anyone know whether isostatic effects have been taken into account with projected sea level rise?”

    Studying the Pine Island Glacier (a Thwaites neighbor) Barletta et al. reported the surprising result that the earth’s crust in West Antarctica is rising 41 mm/year, just under two inches. The researchers also estimate that in 100 years, uplift rates at the GPS sites will be 2.5 to 3.5 times more rapid than currently observed. This means that the grounding line, which is the spot where the marine-based ice shelf of the Pine Island Glacier meets bedrock, will have risen by 8 meters, or 26 feet, over the next century.

    Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability
    http://science.sciencemag.org/content/360/6395/1335

    Liked by 2 people

  9. I have a question…

    OK, so the Thwaites Glacier melts and dumps enough ice into the Southern Ocean to raise sea levels by half a metre. What then is the consequence for the rest of Antarctica? The continent is surrounded by ice sheets so at the very minimum the bottom half metre of all the floating ice is likely to melt. However, the extra buoyancy given to the ice could stress it to the extent that chunks, that would make the recent icebergs from the Larson ice shelf look like minnows, could break off and head for warmer climes.

    The problem, then, isn’t rising sea levels because much of this ice is already floating. The question is more whether the melting ice will influence the sea surface temperature, and more especially the ocean heat content, enough to change the climate in the rest of the world.

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  10. Bill, I don’t know the answer! I think the vast bulk of Antarctica is safe from melting thanks to the Antarctic Circumpolar Current.

    Mark, I note that the third painting of the ‘berg resembles a broken heart. How anyone could get attached to an iceberg is anyone’s guess. This alarm about icebergs all comes back to the point that we now have satellites that can take pictures of them. Many of the ice sheets were first mapped after World War 2. Another example of the way knowledge just brings something new to worry about.

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  11. Mark, this is unlike you. It’s hardly fair to blame the BBC for repeating a story. The “repetition” consisted of reporting a NEW study that calculated the progressive loss of volume of the iceberg, converting this into amounts of freshwater released over time. I find this a legitimate story. A freshwater layer over seawater would curtail oxygenation of the lower layer with potential adverse affects on the fauna, although this would be offset by wind mixing.

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  12. Alan, apologies from me. I stand corrected. I should have read it in more detail this morning before posting the link and comment, but I was dashing off elsewhere. My bad.

    In my partial defence, I have now been conditioned by BBC behaviour over a long period of time.

    Still, I will try to avoid being over-hasty in future. 😕

    Liked by 1 person

  13. Thanks Mark. The Doomsday Glacier is never out of the news for long. The story is also covered at Phys.org, where at least one voice belongs to someone who hasn’t drunk the Koolaid:

    University of Washington ice scientist Ian Joughin, who isn’t part of the research consortium, cautioned that while Thwaites is a big concern, especially the collapse of giant ice cliffs, the earliest his computer simulations show that happening is 200 years from now.

    “We need to take these glaciers seriously without sounding like Chicken Little,” Joughin said in an email.

    How refreshing…

    Elsewhere the story is not so good. We have:

    “The ‘Doomsday’ glacier may soon trigger a dramatic sea-level rise” [Science News for Students] – which should perhaps go in air quotes….. the ice shelf could be gone in 5 years. Except we all know that it won’t.

    “The ‘Doomsday Glacier’ is irreversibly melting, researchers say” [Futurism] Though when you read it, it isn’t so bad:

    “It could fall apart quickly, in decades, or it could be centuries,” Holland told the pub. “And the only way to really know that is through this research.”

    “The radical intervention that might save the ‘doomsday’ glacier” [MIT Technology Review] –

    Researchers are exploring whether building massive berms or unfurling underwater curtains could hold back the warm waters degrading ice sheets.

    Like

  14. “The radical intervention that might save the ‘doomsday’ glacier” [MIT Technology Review] –

    Researchers are exploring whether building massive berms or unfurling underwater curtains could hold back the warm waters degrading ice sheets.”

    I suggest shipping a few JCB onto the ice and chipping small bits away every year, that way a) low lying countries don’t get inundated and b) it will avoid a massive collapse of ice which is likely to upset the energy balance of the oceans and could lead to the onset of the next iceage.

    Like

  15. Mark – thanks for the update on “‘Doomsday Glacier”.

    followed the links back to find who first called it “‘Doomsday Glacier” but with no luck !!!

    anyway from the links
    Associated Press – via the Guardian – “Antarctica’s so-called Doomsday Glacier, nicknamed because it is huge and coming apart”
    “Scientists from around the world are part of a $50m international effort to study the Florida-sized glacier by land, sea and below for the brief time the remote ice is reachable during the Antarctic summer.”

    “What worries scientists is that the leading edge of the huge glacier is breaking apart in many places. Even though total collapse of the glacier could take hundreds or thousands of years, the edge is falling apart much sooner. And if that goes, researchers fear nothing may stop the rest from doing the same.”

    have the researchers/scientists really said that ?

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  16. Dougie, the coiner of the term was Jeff Goodell – see towards the bottom of the opening post. He seems to be proud of his work.

    Bill, I don’t think anyone should lose sleep over Thwaites. There will always be someone suggesting a tech solution – a few years ago an idea was floated to send clouds of brine into the Arctic skies to reflect more sunlight. Can’t remember whose idea that was.

    My own crackpot scheme is to send aluminium chaff [as in Window] to the Lagrange point to reflect sunlight there. What could possibly go wrong?

    Like

  17. Jit – oops should have reread your post (thought that bit was an ad so skipped that last part before”

    now have the Rolling Stone link –
    “The Doomsday Glacier
    In the farthest reaches of Antarctica, a nightmare scenario of crumbling ice – and rapidly rising seas – could spell disaster for a warming planet.
    By JEFF GOODELL MAY 9, 2017”

    well worth a reread if you have time – liked this bit
    “He and his colleagues set up camp at a new spot every few days and drilled holes 300 feet or so into the ice. Then they dropped tubes of nitroglycerin dynamite into these holes and triggered a blast”

    Like

  18. and this bit –
    “In any case, the threat is clear. In a rational world, awareness of these risks would lead to deep and rapid cuts in carbon pollution to slow the warming, as well as investment in more research in West Antarctica to get a clearer understanding of what is going on. Instead, Americans elected a president who thinks climate change is a hoax, who is hellbent on burning more fossil fuels, who installs the CEO of the world’s largest oil company as secretary of state, who wants to slash climate-science funding and instead spend nearly $70 billion to build a wall at the Mexican border and another $54 billion to beef up the military.

    After Kerry returned from Antarctica, we discussed the Trump administration’s attacks on climate science, including the decision to strip every mention of climate change from the White House website. “Such a stunningly Luddite moment,” Kerry says.”

    Like

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