West Antarctica Warming Three Times Faster Than Global Average, Threatening To Destabilize This Unstable Ice Sheet

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"West Antarctica Warming Three Times Faster Than Global Average, Threatening To Destabilize This Unstable Ice Sheet"

This is a repost of a National Center for Atmospheric Research (NCAR) news release (plus links and excerpts from other recent studies at the end).

BOULDER—In a finding that raises further concerns about the future contribution of Antarctica to sea level rise, a new study finds that the western part of the continent’s ice sheet is experiencing nearly twice as much warming as previously thought.

Researchers have determined that the central region of the West Antarctic Ice Sheet (WAIS) is experiencing twice as much warming as previously thought. Their analysis focuses on the  temperature record from Byrd Station (indicated by a star), which provides the only long-term temperature observations in the region. Other permanent research stations with long-term temperature records (indicated by black circles) are scattered around the continent. The color scale shows the correlation between the annual mean temperatures at Byrd Station and the annual mean temperatures at every other grid point in Antarctica. The high correlation (red and orange) across much of the West Antarctic Ice Sheet implies that the record from Byrd Station can provide insight into temperature changes over a large part of the ice sheet. (Image by Julien Nicolas, courtesy of Ohio State University.) This caption was updated [by NCAR] to indicate that the color scale represents correlations, not temperatures.

The temperature record from Byrd Station, a scientific outpost in the center of the West Antarctic Ice Sheet (WAIS), demonstrates a marked increase of 4.3 degrees Fahrenheit (2.4 degrees Celsius) in average annual temperature since 1958. The rate of increase is three times faster than the average temperature rise around the globe for the same period.

The study was published Sunday in the journal Nature Geoscience ["Central West Antarctica among most rapidly warming regions on Earth" (subs. req'd)]. It was conducted by scientists at Ohio State University (OSU), the National Center for Atmospheric Research (NCAR), and the University of Wisconsin-Madison, with funding coming from the National Science Foundation, which is NCAR’s sponsor.

“Our results indicate that temperature increases during the past half century have been almost twice what we previously thought, placing West Antarctica among the fastest warming regions on Earth,” says NCAR scientist Andrew Monaghan, a co-author. “A growing body of research shows that the West Antarctic Ice Sheet is changing at an alarming rate, with pressure coming from both a warming ocean and a warming atmosphere.”

This study reveals warming trends during the summer months of the Southern Hemisphere (December through February), notes co-author David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd Polar Research Center.

“Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does,” Bromwich says.  “Even without generating significant mass loss directly, surface melting on the WAIS could contribute to sea level indirectly by weakening the West Antarctic ice shelves that restrain the region’s natural ice flow into the ocean.”

Researchers consider the WAIS especially sensitive to climate change because the base of the ice sheet rests below sea level, making it vulnerable to direct contact with warm ocean water. Its melting currently contributes 0.3 millimeters to sea level rise each year. This is second only to Greenland, whose contribution to sea level rise has been estimated as high as 0.7 mm per year.

Filling in the data gaps

Due to its location some 700 miles from the South Pole and near the center of the WAIS, conditions at Byrd Station are an important indicator of climate change throughout the region.

In the past, researchers haven’t been able to make much use of the Byrd Station measurements because of incomplete temperature observations. Since its establishment in 1957, the station has not been occupied continuously. A year-round automated station was installed in 1980, but it has experienced frequent power outages, especially during the long polar night when its solar panels can’t recharge.

The new study fills in the data gaps with a powerful computer model of the atmosphere and a numerical analysis method

In addition to offering a more complete picture of warming in West Antarctica, the new study shows for the first time that significant melt is occurring during summer.  Monaghan says the summertime warmth is particularly troubling because that is the season in which enhanced surface melting could most affect the WAIS and potentially weaken the ice shelves that buttress it.

“We’ve already seen enhanced surface melting contribute to the breakup of the Antarctic’s Larsen B Ice Shelf, where glaciers at the edge discharged massive sections of ice into the ocean that contributed to sea level rise,” he says. “The stakes would be much higher if a similar event occurred to an ice shelf restraining one of the enormous WAIS glaciers.”

“West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known,” says Bromwich. “Our study underscores the need for a reliable network of meteorological observations throughout West Antarctica, so that we can know what is happening—and why—with more certainty.”

– NCAR

Related Posts:

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”….

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).

 

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46 Responses to West Antarctica Warming Three Times Faster Than Global Average, Threatening To Destabilize This Unstable Ice Sheet

  1. prokaryotes says:

    West Antarctic rapid glacier retreat may be exceptional during the Holocene http://geology.gsapubs.org/content/41/1/35.abstract

    • prokaryotes says:

      Ice loss from the marine-based, potentially unstable West Antarctic Ice Sheet (WAIS) contributes to current sea-level rise and may raise sea level by ≤3.3 m or even ≤5 m in the future. Over the past few decades, glaciers draining the WAIS into the Amundsen Sea Embayment (ASE) have shown accelerated ice flow, rapid thinning, and fast retreat of the grounding line (GL).

      Our results further suggest either slow GL retreat from the inner ASE shelf throughout the Holocene, or that any episodes of fast GL retreat must have been short-lived. Thus, today’s rapid retreat may be exceptional during the Holocene and may originate in recent changes in regional climate, ocean circulation, or ice-sheet dynamics.

  2. Joan Savage says:

    New York Times published a blunt article on Lisa Jackson’s departure from the EPA, pointing to the frustrations of many with the gridlock in Washington on environmental protection.

    They point to one key success of Jackson’s, the inclusion of carbon dioxide under the Clean Air Act.

    http://www.nytimes.com/2012/12/28/science/earth/lisa-p-jackson-of-epa-to-step-down.html?emc=na&_r=0

    It’s hard to cheer for what was a hard-won policy success in the context of warming of the atmosphere over the WAIS.

    • Mulga Mumblebrain says:

      No ‘success’ is inviolate. In Australia the new generation of hard Right state regimes is viscerally anti-environmental, and is winding back or destroying all the meagre quantum of environmental law established through great effort over the last forty years. Meanwhile, the Rightwing MSM, (led as ever in all things wicked by the Murdoch excrescence), allied with the capitalist Big Business caste, is furiously braying their demands to remove all remaining ‘Green Tape’, ie all environmental laws that get in the way of profit maximisation, their paramount ‘good’.

  3. Paul Klinkman says:

    A block of ice is more stable than a pile of ice cubes. When an ice sheet stays cold, ice slowly flows as a fluid so that all fractures are closed up. When an ice sheet melts once or ten times a year, new moulins, canyons and micro-holes are cut into the whole structure. The rest of the ice sheet has to handle huge stresses on the ice sheet as it slides toward the sea, and fractures spread.

    One ice river in Greenland recently made five miles of progress in 90 minutes.

  4. Joan Savage says:

    “We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost.”

    Potential methane reservoirs beneath Antarctica.
    Nature. 2012 Aug 30;488(7413):633-7.

    Wadham JL, Arndt S, Tulaczyk S, Stibal M, Tranter M, Telling J, Lis GP, Lawson E, Ridgwell A, Dubnick A, Sharp MJ, Anesio AM, Butler CE.

    Full abstract at:
    http://www.ncbi.nlm.nih.gov/pubmed/22932387

    • Sasparilla says:

      Oh boy, although it makes perfect sense (eon’s of carbon based life has lived, died and fallen to the bottom there) that is so not welcome news…to the extreme, especially with parts of the ocean down there warming. So we have a 2nd clathrate gun reloaded down at the South Pole as well.

      • wili says:

        Yes, but presumably it will be a rather slow-motion feedback. Still, it is another way that our initial forcing is likely to set off a whole cascade of additional feedbacks that will serve to keep CO2 levels and temperatures at extremely high rates for far longer than just our own ff-generated GHGs would have done alone.

        • Paul Klinkman says:

          I’d say relatively slow, slower than change in the Arctic.

          How slow is Arctic climate change lately?

          Haven’t a number of Antarctic ice shelves recently collapsed, in particular the Wilkins ice shelf? Isn’t the albedo of the Southern Ocean changing relatively rapidly? Hasn’t the albedo of the Western Antarctic Ice Sheet increased with recent melting?

          Wouldn’t relatively warm water beneath the ocean drive the thawing of the subfloor clathrate?

          • wili says:

            Good points, Klinkman.

            Shakhova certainly thinks that a sudden emission of massive quantities of methane from the East Siberian Continental Shelf is possible at any time.

            Most other scientists, though, seem to think that clathrate release will come slowly (if inexorably). This has been discussed at length at RealClimate and elsewhere. The argument goes that it takes a long time for heat to warm the many meters of overlying mud before it warms deep enough to affect most of the methane hydrates.

            But there may be other mechanisms that release methane–landslides, cracks, chain reactions, other special features of the sea bed landscape…
            I don’t pretend to have any expertise in the area–hence my “presumably.”

      • Mulga Mumblebrain says:

        The speed seems to me to be irrelevant. It is whether it is stoppable or reversible that matters for humanity in the long term (when we will all be dead, but one hopes that our descendants might yet exist).

    • prokaryotes says:

      The researchers estimate that 50 per cent of the West Antarctic Ice Sheet (1 million km2) and 25 per cent of the East Antarctic Ice Sheet (2.5 million km2) overlies preglacial sedimentary basins, containing about 21,000 billion tonnes of organic carbon. Team leader, Professor Wadham said: “This is an immense amount of organic carbon, more than ten times the size of carbon stocks in northern permafrost regions. Our laboratory experiments tell us that these sub-ice environments are also biologically active, meaning that this organic carbon is probably being metabolised to carbon dioxide and methane gas by microbes.” http://climatestate.com/pure-climate-science/item/potential-methane-reservoirs-beneath-antarctica.html#comment-292

      Oh Snap…

  5. David Goldstein says:

    Cue building drumbeat of building climate disequilibrium: “boom-boom-Boom-BOom-BOOm-BOOM!”
    Cue ignoring of said drumbeat: ” crickets “

  6. Naive layman’s question – Interesting that the warming apparently is centered on Byrd and cascades out from there for hundreds of miles. Could activities at (and effluent from) Byrd be a catalyst or cause for these observed changes? Would shutting down Byrd be a possible partial antidote?

    • squidboy6 says:

      No, the amount of energy expended at and getting to that station is nothing compared to the amount that is needed to warm the air and ice up in that vast area.

    • riverat says:

      Interesting that the warming apparently is centered on Byrd and cascades out from there for hundreds of miles.

      In looking at that map of Antarctica the caption for the color scale is “Temperature correlation with Byrd Station”. So the color gradations on the map do not show temperature anomalies but how well correlated the temperatures in those locations are with temperatures at Byrd Stations.

  7. Jim Eager says:

    From the caption to the figure:
    “On this map, the color intensity indicates the extent of warming around Antarctica”

    It does no such thing. The statement is false, full stop.

    The Y axis legend states quite clearly that the color intensity indicates the spacial correlation with the Byrd Station temperature data, showing the much larger area that the Byrd data set is representative of.

    Honestly, I expect far better from Climate Progress than to repeat the same errors that the popular press does out of ignorance.

  8. Colorado Bob says:

    Wettest year on record for England… and still more rain and wind to come
    England has suffered its wettest year on record after the winter deluge pushed rainfall figures to historic levels, the Met Office has confirmed.

    http://www.telegraph.co.uk/topics/weather/9767882/Wettest-year-on-record-for-England…-and-still-more-rain-and-wind-to-come.html

  9. Like Jim Eager (comment #8), I noticed that the figure legend does not accurately describe the figure. The color scale indicates degree of correlation with temperature changes at the Byrd station. The map shows that correlation with the Byrd station decreases (roughly) with distance from the station, as one might expect. My understanding is that the Antarctic Peninsula (above and to the left of the Byrd station in the map) is also warming at a fairly rapid rate, even though its temperatures over time don’t correlate well with those at the Byrd station (perhaps because its temperature is more affected by that of the surrounding sea than is the temperature at the Byrd station).

  10. To Jim Eager – So what you are saying is that this graphic does not indicate warming in increasing intensity as you get closer to Byrd, but accuracy of measurement as you get closer, with the greatest accuracy of measurement closer to Byrd and the lest accuracy farther away? Is that what we are to understand? So are we to understand that the question of whether Byrd is contributing to warming is not germane as there is no perceptible difference in warming, just a difference in measurement. Is that correct?

    • Steve Bloom says:

      No. The study did find warming. This is just the wrong graphic to show it. An actual temp graph might look similar to this, except that it would show the peninsula warming even more.

  11. dhogaza says:

    Someone must’ve picked the correlation graph because it’s more colorful or visually interesting.

    There is a graph series that does show the actual warming at the station:

    http://www.flickr.com/photos/belette/8308813948/

    The press release from NCAR is not wrong, they’ve used the wrong graphic (h/t the stoat at scienceblogs)

  12. Joan Savage says:

    Fig. 4 of the Nature Geoscience article shows over the years 1958-2005 the greatest atmospheric temperature increase by season has been in the Antarctic spring, SON (September October November).

    The other five references compared in the article had also showed those months, SON, to have the greatest temperature increase though not to the extent of the corrected data presented.

    http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1671.html

    • squidboy6 says:

      That link is interesting but the graphic is too small to see unless one buys the article or is a member. It’s enough to see that they’re different but not enough detail.

  13. Merrelyn Emery says:

    Temperatures in W Antarctica have been warming faster than the global average for about 50 years, about the same length of time we have been warned about the breakup of the WAIS, ME

  14. Ray Kondrasuk says:

    Folks, I’m playing the non-scientist, mathematically-challenged denier devil’s advocate:

    If WAIS contributes .3mm annual sea rise and Greenland another .7mm, that’s 1/25th of an inch, or a four-inch rise over the century.

    What’s needed for a more convincing concern… positive feedbacks? Thermal expansion?

    How does one justify those meter+ century’s-end forecasts?

    • Merrelyn Emery says:

      Linear projections don’t work when you are dealing with systemic change, ME

    • Steve Bloom says:

      It’s 1) the trend, noting that large climate responses always start small, but most important, 2) the paleoclimate record, which shows that both the GIS and WAIS can’t survive current CO2 levels, and that under comparable natural conditions (with distinctly less rapid forcing than currently) melting ice sheets have contributed to more than a meter of sea level rise per century.

    • prokaryotes says:

      Hansen (2007) suggested that a 10-year doubling time was plausible, pointing out that such a doubling time from a base of 1 mm per year ice sheet contribution to sea level in the decade 2005-2015 would lead to a cumulative 5 m sea level rise by 2095.” http://www.countercurrents.org/glikson050411.pdf

    • Joan Savage says:

      Nice challenge. Short way to answer is rather like a Physics 101 lesson on the difference between speed and acceleration.

      1. Current rates of continental melt contributions to sea level (0.3 mm plus 0.7 mm SLR per year) don’t include the increase in rates observed to date or the likelihood of accelerated future melt rate.

      2. Average global thermal expansions of the surface and subsurface ocean are also trending upward. Some parts of the ocean are warming and expanding more rapidly than others, so keep in mind it’s the overall increase.

    • Mark E says:

      This question reminds me of the guy who super-glued a concrete brick to his gas pedal.

      When the car was doing 5mph, he told himself there was nothing to worry about, since the car was only doing a measly 5 mph.

    • Jim Eager says:

      Ray wrote: “If WAIS contributes .3mm annual sea rise and Greenland another .7mm, that’s 1/25th of an inch, or a four-inch rise over the century. What’s needed for a more convincing concern?”

      A realization that a linear extrapolation at a *fixed* trend rate can not possibly describe what is in reality an exponentially increasing trend rate.

      Greenland’s contribution to sea level rise has not remained fixed as you assume in your simplistic calculation, it has increased over the past 10 years, doubling from 0.5 mm/yr in 2002 to 1mm in 2012. That is a doubling time of 10 years. If that ten year doubling rate were to continue, by 2102 Greenland’s contribution would be 512 mm each year. That is more than half a meter per year, never mind per century.

      Fortunately that sustained 10 year doubling rate of is not likely to continue–it would result in a cumulative sea level rise of over 7 meters by 2102 and thus complete deglaciation of Greenland–but a cumulative sea level rise of a meter or more from Greenland alone by 2100 is well within possibility.

  15. Jack Burton says:

    This flies in the face of the Denier’s fascination with sea ice area growth down around Antarctica. This feature has given new and vocal support to all the deniers out there flooding comments sections across the internet.
    In reality we know there is melting of land based ice and ice shelf breakups is some areas. Sometimes very large and fast breakups.
    My worry, as others noted, is the feedback potential down there. Seriously, take the arctic conditions as of late, add in the Antarctic conditions, and we could see a very rapid flip in world weather conditions brought on by jet stream changes and non-linear positive feed backs. Why would this warming process be linear. We can’t imagine what awaits us in the coming years, climate can flip and flip hard and fast. That is what I am watching for in the Arctic. Britain’s increasingly insane weather may be a hint, plus hurricane Sandy’s odd behavior. Surprise is the new normal! Bad surprises coming, lots of them!

  16. Jim Eager says:

    Wili, indeed, the last time earth’s atmosphere contained 390 ppm CO2 was 2.8 to 3.2 million years ago during the mid-Pliocene, which means the longer current CO2 level remains at 390 or above the more certain planetary temperature will rise by 3C or more and that sea level will rise by 20 meters or more.

  17. Merrelyn Emery says:

    The British expedition drilling through to Lake Ellsmore has failed so any possible life down there remains safe for the moment, ME

  18. prokaryotes says:

    James Hansen and Makiko Sato: Update of Greenland Ice Sheet Mass Loss: Exponential? 26 December 2012 http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf

  19. Chris says:

    Every time I see these headlines, it’s always along the lines of “Something is worse than we previously expected…” I’m just curious, have there been any studies that started out “Actually it’s not that bad, we overreacted before.”

    • prokaryotes says:

      One reason for underestimation is because the science advances very “rapidly” and since the official IPCC report is released only every 5 years, kept very conservative and underplays with messaging of findings.

  20. Lars Karlsson says:

    To the blog owner: Please fix the erroneous statement in the figure caption “On this map, the color intensity indicates the extent of warming around Antarctica.” This error has already been pointed out by several commentors.

  21. Calamity Jean says:

    “A year-round automated station was installed in 1980, but it has experienced frequent power outages, especially during the long polar night when its solar panels can’t recharge.”

    Clearly the station needs a wind turbine. I assume it’s plenty windy there in winter, so it wouldn’t need to be a big one.

  22. wili says:

    Thanks for reminding us of that Hansen/Sato paper on Climate Sensitivity, P.

    The takeaway quote, for me, is on page 21:

    “A more important test of ice sheet variability would be during the middle Pliocene when we find sea level fluctuations of 20-40 m (Fig. 2) associated with global temperature variations between today’s temperature and +3°C.”

    IIRC, CO2 levels in the mid-Pliocene were comparable to our current levels.