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Large Antarctic glacier thinning 4 times faster than it was 10 years ago: “Nothing in the natural world is lost at an accelerating exponential rate like this glacier.”

By Joe Romm on August 13, 2009 at 9:02 pm

"Large Antarctic glacier thinning 4 times faster than it was 10 years ago: “Nothing in the natural world is lost at an accelerating exponential rate like this glacier.”"

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A BBC story on the new study, “The spatial and temporal evolution of Pine Island Glacier thinning, 1995 – 2006,” (subs. req’d) explains:

Calculations based on the rate of melting 15 years ago had suggested the glacier would last for 600 years. But the new data points to a lifespan for the vast ice stream of only another 100 years.

The rate of loss is fastest in the centre of the glacier and the concern is that if the process continues, the glacier may break up and start to affect the ice sheet further inland.

One of the authors, Professor Andrew Shepherd of Leeds University, said that the melting from the centre of the glacier would add about 3cm to global sea level.

“But the ice trapped behind it is about 20-30cm of sea level rise and as soon as we destabilise or remove the middle of the glacier we don’t know really know what’s going to happen to the ice behind it,” he told BBC News.

When we last left Antarctic research, it turned out that the great ice sheet’s temperature had risen by up to about 3°C (5.4 °F) in the past 50 years, which is the fastest increase in the southern hemisphere (see “Antarctica has warmed significantly over past 50 years, revisited“):

antarctica2.jpg

Antarctica is disintegrating much faster than almost anybody imagined.  In 2001, the IPCC “consensus” said neither Greenland nor Antarctica would lose significant mass by 2100. They both already are.  As Penn State climatologist Richard Alley said in March 2006, the ice sheets appear to be shrinking “100 years ahead of schedule.”

http://www.open.ac.uk/port/images/z_Antarctica.gifPine Island Glacier is where the first “A” in “Antarctica” in the figure above [see figure on right, click to enlarge].  It is of special interest, as the BBC notes:

Pine Island glacier has been the subject of an intense research effort in recent years amid fears that its collapse could lead to a rapid disintegration of the West Antarctic ice sheet.

The rest of this post will survey what we now know about the increasingly unstable West Antarctic ice sheet (WAIS) and the threat it poses to humanity “” or is that the threat humanity poses to it? “” if we continue on our current suicidal emissions path.  Regular readers can skip the rest of this post since I’m mostly excerpting, “Q: How much can West Antarctica plausibly contribute to sea level rise by 2100?” [A:  3 to 5 feet].

A 2007 study found “The current loss of mass from the Amundsen Sea embayment of the West Antarctic ice sheet [WAIS] is equivalent to that from the entire Greenland ice sheet” (see the new survey report Antarctic Climate Change and the Environment draft here).  And WAIS’s 2007′s ice loss was 75% higher than 2006′s (see “The Antarctic ice sheet hits the fan“).

The warming of the WAIS is most worrisome (at least for this century) because it’s going to disintegrate long before the East Antarctic Ice Sheet does “” since WAIS appears to be melting from underneath (i.e. the water is warming, too), and since, as I wrote in the “high water” part of my book, the WAIS is inherently less stable:

Perhaps the most important, and worrisome, fact about the WAIS is that it is fundamentally far less stable than the Greenland ice sheet because most of it is grounded far below sea level. The WAIS rests on bedrock as deep as two kilometers underwater. One 2004 NASA-led study found that most of the glaciers they were studying “flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.” A 2002 study in Science examined the underwater grounding lines-the points where the ice starts floating. Using satellites, the researchers determined that “bottom melt rates experienced by large outlet glaciers near their grounding lines are far higher than generally assumed.” And that melt rate is positively correlated with ocean temperature.

The warmer it gets, the more unstable WAIS outlet glaciers will become. Since so much of the ice sheet is grounded underwater, rising sea levels may have the effect of lifting the sheets, allowing more-and increasingly warmer-water underneath it, leading to further bottom melting, more ice shelf disintegration, accelerated glacial flow, and further sea level rise, and so on and on, another vicious cycle. The combination of global warming and accelerating sea level rise from Greenland could be the trigger for catastrophic collapse in the WAIS (see, for instance, here).

You can read every thing a laymen could possibly want to know about what the recent study on Antarctic warming does and doesn’t show at RealClimate here.

A couple of new papers published by Nature in March have been portrayed as suggesting the WAIS as a whole may be stabler than was previously thought.  Yet the first paper, “Obliquity-paced Pliocene West Antarctic ice sheet oscillations” (subs. req’), concludes:

Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to approx3 °C warmer than today and atmospheric CO2 concentration was as high as approx400 p.p.m.v.

We’ll be at 400 ppm by 2020.  We’re on track to be more than 5°C warmer by 2100.  So the first paper doesn’t seem terribly reassuring.

The second paper by Pollard and DeConto (the one that got all the attention), “Modelling West Antarctic ice sheet growth and collapse through the past five million years,” (subs. req’), notes, “Recent melt rates under small Antarctic ice shelves are inferred to be increasing dramatically” and concluded:

“¦ the WAIS will begin to collapse when nearby ocean temperatures warm by roughly 5 °C. Global climate and regional ocean modelling is needed to predict when and if future ocean temperatures and melt rates under the major Antarctic ice shelves will increase by these amounts, and if so, for how long.

Are you reassured yet?

I would note that West Antarctica land temperatures have risen up to 3°C over the past 50 years “” some 4 times what the planet as a whole has warmed. And both Hadley and MIT say the planet will warm more than 5°C by 2100, with a 10% chance of warming more than 7°C (see M.I.T. doubles its projection of global warming by 2100 to 5.1°C and “Hadley Center warns of “Catastrophic” 5-7°C warming by 2100 on current emissions path.  And while the ocean warms less than the nearby land, the new study Antarctic Climate Change and the Environment warns: “UP TO one-third of all Antarctic sea ice is likely to melt by the end of the century.”  So we may yet see polar amplifacation near the South Pole (see “What exactly is polar amplification and why does it matter?“).

Dr. Robert Bindschadler of NASA, who has been an active Antarctic field researcher for the past 25 years, commented on the new study (here):

I’m familiar with the Pollard/DeConto work. They previewed it last fall at an annual science workshop I organize on West Antarctic research. Their model lacks the detail to get the fastest dynamic responses, so the 0.5m/century rate for sea level rise should only be viewed as a lower bound (and a poor one, at that).

Their model is better at getting the longer-term quasi-equilibrium response (it just takes their model a little longer to get there), so it ‘s very interesting that they demonstrate the sensitivity to the ocean temperature. That thinking is certainly where Antarctic scientists are being led by both data and models.

Moreover, the entire WAIS need not collapse for it to contribute to catastrophic sea level rise this century.

The Antarctic Peninsula alone contains “a total volume of 95,200 km3 (equivalent to 242 mm of sea-level; Pritchard and Vaughan, 2007), roughly half that of all glaciers and ice caps outside of either Greenland or Antarctica” (see Chapter 5 here)  “” that would be more than 9 inches of sea level rise from a region of WAIS losing its protective ice shelves on both sides at an alarming pace.

But it is westernmost part of WAIS, that borders on the Amundsen Sea, and that includes Pine Island, that we need to worry most about, as AP reported earlier this year:

Glaciers in Antarctica are melting faster and across a much wider area than previously thought, a development that threatens to raise sea levels worldwide and force millions of people to flee low-lying areas, scientists said Wednesday.

Researchers once believed that the melting was limited to the Antarctic Peninsula, a narrow tongue of land pointing toward South America. But satellite data and automated weather stations now indicate it is more widespread.

The melting “also extends all the way down to what is called west Antarctica,” said Colin Summerhayes, executive director of the Britain-based Scientific Committee on Antarctic Research.

“That’s unusual and unexpected,” he told the Associated Press in an interview.

By the end of the century, the accelerated melting could cause sea levels to climb by 3 to 5 feet “” levels substantially higher than predicted by a major scientific group just two years ago….

The biggest of the western glaciers, the Pine Island Glacier, is moving 40% faster than it was in the 1970s, discharging water and ice more rapidly into the ocean, said Summerhayes, a member of International Polar Year’s steering committee.

The Smith Glacier, also in west Antarctica, is moving 83% faster than in 1992, he said.

The glaciers are slipping into the sea faster because the floating ice shelf that would normally stop them “” usually 650 to 980 feet thick “” is melting. And the glaciers’ discharge is making a significant contribution to increasing sea levels.

So we have the serious potential for 3 to 5 feet of sea level rise just from WAIS this century “” and that is on top of whatever we get from thermal expansion of the ocean and Greenland.  And on top of whatever we get from the melting of the inland glaciers, whose contribution was recently increased:

New research published this month in the journal Geophysical Research Letters found that melting glaciers will add at least 7 inches to the world’s sea level “” and that’s if carbon dioxide pollution is quickly capped and then reduced.

Far more likely is an increase of at least 15 inches and probably more just from melting glaciers, the journal said.

So it increasingly looks like we are facing a very serious risk of more than 5 feet of total sea level rise by 2100 on our current emissions path.

But this is almost not news anymore “” see Startling new sea level rise research: “Most likely” 0.8 to 2.0 meters by 2100. Indeed, an important Science article from 2007 used empirical data from last century to project that sea levels could be up to 5 feet higher in 2100 and rising 6 inches a decade (see Inundated with Information on Sea Level Rise.  Another 2007 study from Nature Geoscience came to the same conclusion (see “Sea levels may rise 5 feet by 2100“). Leading experts in the field have a similar view (see “Amazing AP article on sea level rise” and “Report from AGU meeting: One meter sea level rise by 2100 “very likely” even if warming stops?“).  Even a major report signed off on by the Bush administration itself was forced to concede that the IPCC numbers are simply too out of date to be quoted anymore (see US Geological Survey stunner: Sea-level rise in 2100 will likely “substantially exceed” IPCC projections).

Did I mention the time to act is now!

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25 Responses to Large Antarctic glacier thinning 4 times faster than it was 10 years ago: “Nothing in the natural world is lost at an accelerating exponential rate like this glacier.”

  1. Greg Robie says:

    It is posts like this that have made Climate Progress invaluable. It is also trends like this in the science that make ACES less than valuable as the action that is called for.

  2. Lou Grinzo says:

    Thanks for pulling together so much information on this, even if it is depressing as hell…

  3. Erik Schimek says:

    I need to ask a stupid question: How does one convert statements like ‘a temperature rise of 5 degrees C’ to the Fahrenheit scale?

    I did a search for a conversion chart, but they’re based on absolute temperatures … not a change in temperature.

    Thank you.

  4. Greg Robie says:

    How about through the use of proportions, i.e. 180/100 = X/5; or X = 9? BTW, isn’t only stupid question is the one you don’t ask? ;)

  5. paulm says:

    I think you mentioned that the time to act is yesterday.

    http://climateprogress.org/2009/08/09/climate-change-seen-as-threat-to-u-s-security/

    Lester Brown on tippings…
    http://www.grist.org/article/2009-08-12-a-civilizational-tipping-point/

    We are in a race between tipping points in nature and in our political systems. Can we phase out coal-fired power plants before the melting of the Greenland ice sheet becomes irreversible? Can we gather the political will to halt deforestation in the Amazon before its growing vulnerability to fire takes it to the point of no return? Can we help countries stabilize population before they become failing states?

    We have the technologies to restore the earth’s natural support systems, to eradicate poverty, to stabilize population, and to restructure the world energy economy and stabilize climate. The challenge now is to build the political will to do so. Saving civilization is not a spectator sport. Each of us has a leading role to play.

  6. caerbannog says:

    A couple of years ago, I attended a lecture given by Dr. Jeff Severinghaus at the Scripps Institution of Oceanography. When the topic of sea-level rise came up, he said (with all the appropriate caveats, of course) that he foresaw a sea-level rise of 2-6 feet over the next century. I’m not going to put words in his mouth, but I rather suspect that he’s leaning toward the higher end of that range now.

  7. paulm says:

    Someone telling it like it is….

    http://www.guardian.co.uk/environment/2009/aug/13/coal-stations-activism

    He added: “There is no such thing as a free lunch and we’re not going to get a free lunch around coal. So my view would be if the government wants to provide a lightning rod for public disagreement or dissent around coal, then start building a new coal-fired power station, and the orang-utan costumes will be dusted off from around the planet and people will come and say this is wrong. And two wrongs don’t make a right. People say “oh there is one a week opening in China”. And? I don’t think that’s a good enough reason.”

    Day said: “Politicians are there to make the hard decisions. And there are some really hard decisions coming up. And they’re hard because they’re not the kind of decisions that individuals particularly want to have taken. How many short- to medium-haul flight holidays does anyone really need to have a year? Ed Miliband interestingly said something like ‘don’t worry your holiday flights are safe with me’. But we know that we need to be encouraging and supporting, through a combination of stick and carrot, some change to behaviours.”

  8. Phil S says:

    Strangely enough a vast security fence is being built around Didcot coal fired power station in Oxfordshire, UK. Education and ballot papers are the best way forward.

  9. Leland Palmer says:

    It all appears to be happening. The polar caps really do appear to be melting.

    Lovelock’s claim that climate modelers don’t know much about ice sheet dynamics appears to be correct.

    What else was he right about, with his predictions of 6 billion dead by 2100?

    [JR: Let's not go overboard here -- EVERYONE has said "climate modelers don't know much about ice sheet dynamics" -- including the IPCC itself. Doesn't mean 6 billion will die!]

    http://www.rollingstone.com/politics/story/16956300/the_prophet_of_climate_change_james_lovelock

    In Lovelock’s view, the scale of the catastrophe that awaits us will soon become obvious. By 2020, droughts and other extreme weather will be commonplace. By 2040, the Sahara will be moving into Europe, and Berlin will be as hot as Baghdad. Atlanta will end up a kudzu jungle. Phoenix will become uninhabitable, as will parts of Beijing (desert), Miami (rising seas) and London (floods). Food shortages will drive millions of people north, raising political tensions. “The Chinese have nowhere to go but up into Siberia,” Lovelock says. “How will the Russians feel about that? I fear that war between Russia and China is probably inevitable.” With hardship and mass migrations will come epidemics, which are likely to kill millions. By 2100, Lovelock believes, the Earth’s population will be culled from today’s 6.6 billion to as few as 500 million, with most of the survivors living in the far latitudes — Canada, Iceland, Scandinavia, the Arctic Basin.

    By the end of the century, according to Lovelock, global warming will cause temperate zones like North America and Europe to heat up by fourteen degrees Fahrenheit, nearly double the likeliest predictions of the latest report from the Intergovernmental Panel on Climate Change, the United Nations-sanctioned body that includes the world’s top scientists. “Our future,” Lovelock writes, “is like that of the passengers on a small pleasure boat sailing quietly above the Niagara Falls, not knowing that the engines are about to fail.” And switching to energy-efficient light bulbs won’t save us. To Lovelock, cutting greenhouse-gas pollution won’t make much difference at this point, and much of what passes for sustainable development is little more than a scam to profit off disaster.

    Lovelock has a nasty habit of being right, and seeing things first.

    Of course, he could also be underestimating the problem, out of normal scientific conservatism.

    What a shame that a human race that could produce such a man can also produce Mark Morano.

  10. Leland Palmer says:

    We need to seize the coal fired power plants, and convert them to biomass or biochar fuel, enhanced efficiency via oxyfuel combustion and a topping cycle, and subsequent carbon capture and storage.

    Most coal plants are located on rivers for cooling water. All of the territory upstream of the coal plants on those rivers becomes potential biomass or biochar collection area. Biomass and biochar could be transported down the rivers to the converted coal fired power plants by barge – the cheapest form of transport.

    By doing this, we could transform the worst problem (coal fired power plants) into the best solution (carbon negative power plants). With these converted coal fired power plants, we could put a billion tons of carbon per year back underground, in the U.S., and power our society this way at the same time.

    Seize the coal plants, and convert them. Pay for the conversion by increasing their efficiency.

    Time is running out.

  11. Giove says:

    As I understand it, current climate models include simulation for a number of factors: ice melting due to atmospheric and marine heat transport and direct solar irradiation, geological heat inputs, mybe physical and biological feedbacks and of course the various contributions to heat storage. Right?

    Now, about the estimation of sea level rise the factors considered are ice melting and the thermic expansion of oceans. Right?

    A question has been troubling me since some time: when the ice sheet disappears from Greenland or Antarctica this can have a very pronounced geological effect too. Like a raft which suddenly becomes much lighter these 2 lands would pop up like a cork, thus exacerbating global sea level rises. I suspect this could be a fairly quick process, with a response closely following disappearance of the ice layer. Has this been considered in models and predictions?

    In predicting

  12. Giove says:

    forgot: at the same time, when Greenland and Antarctica pop up, the ocean and sea floors will sink, putting a lot of weight on all coastal areas and the edges of continental shelves. This might bend continents mybe .. and thus cause a lot of earthquakes in addition of exacerbated sinking of coastal areas. (are we experiencing an increasing trend in earthquakes too?)

  13. Giove says:

    Sorry for replying to myself .. another thing came to my mind.

    One additional geologic effect is that the sudden increase in surface temperature will slowly propagate to the inner part of faults changing the properties of rocks and allowing faults to move faster .. and thus changing earthquake patterns. This is a very slow process, I imagine, probably negligible at the time scale of global warming.

  14. Giove says:

    yet another thing sorry. Greenland and Antarctica are “caved in” by the enormous weight of the ice sitting on them. Like flexible rafts, the center of the continents should be sinking more than the edges. When and if they “pop up” in response to the decrease of ice they should change shape, with their center part raising higher .. This should nonlinearly increment the speed of ice flow, compounding the release of methane and the albedo effect and making the tipping point sharper.

  15. caerbannog says:


    [JR: Let's not go overboard here -- EVERYONE has said "climate modelers don't know much about ice sheet dynamics" -- including the IPCC itself. Doesn't mean 6 billion will die!]

    Actually, I’d be willing to wager that over 6 billion people will die in the next hundred years, global-warming or no global-warming!! ;) ;)

    But unchecked global-warming will make many of those 6 billion lives a lot more miserable in the interim…

  16. paulm says:

    Lester Brown on tippings…
    http://www.grist.org/article/2009-08-12-a-civilizational-tipping-point/

    We are in a race between tipping points in nature and in our political systems. Can we phase out coal-fired power plants before the melting of the Greenland ice sheet becomes irreversible? Can we gather the political will to halt deforestation in the Amazon before its growing vulnerability to fire takes it to the point of no return? Can we help countries stabilize population before they become failing states?

    We have the technologies to restore the earth’s natural support systems, to eradicate poverty, to stabilize population, and to restructure the world energy economy and stabilize climate. The challenge now is to build the political will to do so. Saving civilization is not a spectator sport. Each of us has a leading role to play.

  17. paulm says:

    Giove, some good points. Maybe the increase in earthquake and volcanic activity associated with the polar melts are what trigger the switch back to a cooler climate due 4eg to aerosols etc.

  18. Chris Winter says:

    Erik Schimek wrote: “I need to ask a stupid question: How does one convert statements like ‘a temperature rise of 5 degrees C’ to the Fahrenheit scale?

    [JR: Multiply by 9/5 = 1.8. 5C change = 9F change.]

    I did a search for a conversion chart, but they’re based on absolute temperatures — not a change in temperature.”

    Try this NIST page:

    http://physics.nist.gov/Pubs/SP811/appenB9.html#TEMPERATURE

  19. George Ennis says:

    This news is certainly disturbing. What has disturbed be the most in the last few weeks in watching the utter insanity around the Health Care reform debate. Watching the inability of of much of the public to engage in any kind of thoughtful discussion on this matter leaves me doubting that the discussion will be any better and perhaps more unhinged when it comes to meaningful climate change legislation.

  20. Sasparilla says:

    George, that’s a great point. Its disturbing to watch it play out. One can only hope you’re wrong about what will happen with the climate legislation. On the bright side its already through the house and its just the Senate remaining for the climate change stuff (keeping fingers crossed).

  21. Bob Wright says:

    Its time to think about practical low risk geoengineering. Some ideas:

    Pulverized low carbon fly ash or pumice distributed from commercial and military aircraft. (Yes, someone will get a lung cancer, but not all 6 billion of us!)

    Pulverized calcium carbonate and CO2 weathering minerals (like wollastonite) spread on the seafloor near endangered reefs. With possible current modifications? Probably not practical.

  22. espiritwater says:

    Giove, what about pole shift as a result of large scale crustal displacement? (Guess that includes ice displacement as well?)

  23. espiritwater says:

    If large chunks of Antarctica collapsed into the ocean, could it inundate areas as high up as Georgia, in the U.S.?