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Antarctic Ice Shelf Disintegration Underscores a Warming World

By Joe Romm  

"Antarctic Ice Shelf Disintegration Underscores a Warming World"

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That is the breaking news today from the National Snow and Ice Data Center (NSIDC) and the British Antarctic Survey:

Satellite imagery from the [NSIDC] reveals that a 13,680 square kilometer (5,282 square mile) ice shelf has begun to collapse because of rapid climate change in a fast-warming region of Antarctica.

In the past 50 years, the western Antarctic Peninsula has experienced the biggest temperature increase on Earth, rising by 0.5 degree Celsius (0.9 degree Fahrenheit) per decade. NSIDC Lead Scientist Ted Scambos, who first spotted the disintegration in March, said, “We believe the Wilkins has been in place for at least a few hundred years. But warm air and exposure to ocean waves are causing a break-up.”

You can see a video of the ice-shelf post-disintegration taken from an airplane here.

Satellite images indicate that the Wilkins began its collapse on February 28; data revealed that a large iceberg, 41 by 2.5 kilometers (25.5 by 1.5 miles), fell away from the ice shelf’s southwestern front, triggering a runaway disintegration of 405 square kilometers (160 square miles) of the shelf interior (Figure 1 — click to enlarge).

nsidc1.jpg

That is “seven times the size of Manhattan” as Seth Borenstein of the AP helpfully points out. He notes “The rest of the Wilkins ice shelf, which is about the size of Connecticut, is holding on by a narrow beam of thin ice.” The ice shelf is floating, so it won’t add to sea level rise. Such occurrences are “more indicative of a tipping point or trigger in the climate system,” said Sarah Das, a scientist at the Woods Hole Oceanographic Institution. Back to the NSIDC:

The edge of the shelf crumbled into the sky-blue pattern of exposed deep glacial ice that has become characteristic of climate-induced ice shelf break-ups such as the Larsen B in 2002. A narrow beam of intact ice, just 6 kilometers wide (3.7 miles) was protecting the remaining shelf from further breakup as of March 23 (Figure 2 — click to enlarge).

nsidc2.jpg

BAS glaciologist David Vaughan said of the ice shelf, which is supported by a single strip of ice strung between two islands, “Wilkins is the largest ice shelf on West Antarctica yet to be threatened. This shelf is hanging by a thread.” Associate Professor Cheng-Chien Liu at Taiwan’s National Cheng-Kung University (NCKU) also responded, requesting high-resolution color satellite images of the area from Taiwan’s Formosat-2 satellite (Figure 3 — click for high resoluation):

nsidc3.jpg

If this is global cooling, I’d hate to see what global warming looks like.

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21 Responses to Antarctic Ice Shelf Disintegration Underscores a Warming World

  1. Mauri Pelto says:

    Wilkins Ice Shelf is five degrees further south than the Larsen Ice Shelf bringing the issue closer to the main ice sheet. Ice shelves such as this owe their stability to pinning points, places where the floating ice shelf contacts solid ground either beneath or at the margin of the shelf. In this case three islands Rothschild, Charcot, and Lataday Island are the pinning points. As an ice shelf thins, its connection with the pinning points begins to weaken, making it more prone to the calving collapse. The video of 27 seconds from the British Anarctic survey is worth a close look. Shows the size of the icebergs and how it is not melting but calving that is causing the demise.

  2. Paul K says:

    Since neither the rest of Antarctica nor the surrounding ocean has experienced the same warming as the western peninsula, could this local phenomenon have some other cause?

  3. tidal says:

    Paul K, maybe it is an undersea volcano melting it from underneath… you never know… good point.

  4. Earl Killian says:

    In 1993, scientists predicted that Wilkins would break apart within 30 years. David Vaughan, one of those scientists, said today “We predicted it would happen, but it’s happened twice as fast as we predicted.” I think that’s the point: scientists are generally underestimating how fast the Earth is responding to the greenhouse gases we’ve already put into the atmosphere. And yet each year we generally add even more than the previous year.

  5. Paul K says:

    Feeling the right since presenting a plan, I ask you only to consider, with all the knowledge being gathered, the possibility that elevated CO2 concentrations are a symptom, not a cause.

  6. Earl Killian says:

    Paul K, we have a very good idea of how much fossil fuel has been extracted from the Earth and burned. This data is presented in annual reports, taxed by governments, etc. We know that burning fossil fuels created CO2. We know that CO2 is a greenhouse gas. Basic physics can be used (and has been since 1896) to estimate the warming that results from addition of CO2 to the atmosphere. This analysis has been refined, updated, and checked and double-checked in the 1930s, 1950s, 1960s, 1970s, and so on. Only later did scientists introduce global climate models to better understand the subtle interactions between various feedbacks; these global models did not however alter the basic physics conclusion. What part of this long history of science do you dispute? Do you believe that CO2 from burning fossil fuels somehow selectively migrates to outer space, while the natural stuff sticks around as a “symptom”? Note further than ice and sediment cores have allowed us to go back 60 million years and look at climate conditions under different conditions. This data too is consistent with the basic physics and climate models.

  7. Paul K says:

    Earl Killian,
    I believe that burning fossil fuel is wrong for many reasons. Impact on the carbon cycle is one of them but, for me, it is not a very important one. I appreciate the passion Joe and you and others have for AGW. To me it is almost irrelevant to the nuts and bolts of transforming to a non fossil fuel world. As I’ve said before, in the however unlikely event that AGW is definitively disproved, I’ll still be about replacing fossil fuels. I think you would too.

  8. Alan Roberta says:

    The latest news about climate change is so alarming (the right wing would say alarmist) as to make many people want to plant their aching heads in the sand. Some scientists using advanced computer models now argue that if we want to stop the Earth from warming, the amount of carbon we should be emitting is … none. None? As in, zero? As in, shutting down the global industrial economy? After all, global energy demand is expected to accelerate until at least 2020. Yet attempts even to slow the rate of increase of carbon emissions have paralyzed world politics for more than a decade.

  9. Bob Tisdale says:

    For the last 29+ years, there has been no Antarctic warming. The trends are negative. Find another reason for the calving of an ice island. It’s not AGW.
    SoPol Negative Trend:
    http://tinypic.com/fullsize.php?pic=ehrp3&s=3&capwidth=false
    SoPol Land Negative Trend:
    http://tinypic.com/fullsize.php?pic=35bxmy1&s=3&capwidth=false
    SoPol Ocean Negative Trend:
    http://tinypic.com/fullsize.php?pic=2nle1yp&s=3&capwidth=false
    Graphs are of MSU data

  10. Bob Tisdale says:

    There’s also an oceanic connection between El Nino oscillations and the Southern Ocean.
    http://www.jpl.nasa.gov/releases/2002/release_2002_54.html
    Full paper here.
    http://neptune.gsfc.nasa.gov/publications/pdf/pubs2002/2_Southern_Ocean_Climate.pdf
    Regards

  11. Joe says:

    Yes, Bob. I know. The leading experts in the field are wrong. You’ve caught them in a lie. Great job — not!

    The Peninsula has been warming. So has the water.

  12. Nylo says:

    Congrats Joe, you found a 5% of the Anctartica that is warming. How unlucky that the other 95% is cooling, and when averaged, the cooling trend prevails. Sea ice extension in the south continues to reach positive records year after year. In spite of AGW.

    This fixation with the Peninsula thing is a classic example of cherry-picking and is what climatic science shouldn’t be about.

  13. Earl Killian says:

    Paul K, it does not comfort me that you are for replacing fossil fuels if you are going to suggest that CO2 is a symptom, when in fact the overwhelming evidence is that it is the root of the problem. Again, I ask on what basis you dispute the science that CO2 is a greenhouse gas?

  14. Earl Killian says:

    http://www.realclimate.org/index.php/archives/2006/07/peter-doran-and-how-misleading-talking-points-propagate/
    is titled “Peter Doran and how misleading talking points propagate”. Apparently they are still propagating.
    “Peter Doran, the lead author on a oft-cited, but less-often read, Nature study on Antarctic climate in 2002 had an Op-Ed in the NY Times today decrying the misuse of his team’s results in the on-going climate science ‘debate’. … But like so many results in this field, it has become a politicized ‘talking point’, shorn of its context, that is mis-quoted and mis-used by many who should (and often do) know better. Doran complained about the media coverage of his paper at the time, and with the passage of time, the distortion has predictably increased. Give it another few years, maybe we’ll be having congressional hearings about it…”

    Please see also
    http://www.realclimate.org/index.php/archives/2004/12/antarctic-cooling-global-warming/
    http://www.realclimate.org/index.php/archives/2006/03/catastrophic-sea-level-rise-more-evidence-from-the-ice-sheets/
    http://www.realclimate.org/index.php/archives/2008/02/antarctica-is-cold/

  15. Peter Foley says:

    Doesn’t a small part of the ice have to calve every summer to prevent the build up of the ice pack– Otherwise we have a ‘tipping point’ of runaway ice build up. Notice how the area numbers seem to grow through miracle of ice spreading over the sea to puff up the spin. The numbers needed are the fraction of annual ice-fall(snow) volume to ice loss. If much greater or lower then one–start paying attention. In other words- move on to the next spun event folks, another normal event of ice movement isn’t proof of AGW.

  16. David B. Benson says:

    Peter Foley & Nylo — The Antarctic Peninsula has definitely been warming over the last several decades. The Polar Vortex, the permanent wind around the Antarctic, has moved further south, leaving more of the Antarctic Penensula exposed to heating influences. Not so for all the area still to the south of the Polar Vortex, where it rarely even snows..

    That’s how I undersand it.

  17. Paul K says:

    Earl Killian,
    Of course CO2 is a greenhouse gas, never said it wasn’t. The question is the effect. The climate catastrophe predicted here depends on assumed positive forcings and feedbacks greatly multiplying the effect of CO2 alone. These assumptions have not been confirmed. I accept the IPCC as authoritative. The IPCC gives 85% confidence to its 3C +/- 1.5C sensitivity to doubled CO2. Why should anyone have 100% confidence in the even higher sensitivity which Joe claims is the case?

  18. Earl Killian says:

    Paul K, perhaps I misunderstood your symptom vs. effect comment then, but I still can’t figure out what it means. Leaving that behind, I am not aware of Joe claiming that the IPCC’s estimate of climate sensitivity is wrong. There are two points I know he raises on the IPCC report.

    One is the IPCC comments on sea level rise. The IPCC report says that if we ignore dynamic processes, the temperature increase will have a certain effect on sea level. The IPCC ignores dynamic processes because they cannot figure out an accurate way to predict something that chaotic. However, ignoring them is also a problem because they appear to be the primary effect at work. So unfortunately they have a prediction that is of the form “If A then B” where A is very likely false. That makes the IPCC prediction in this case essentially useless, although technically true.

    The second thing is that the IPCC is explicitly estimating the short-term climate sensitivity. This is how Earth responds to changes over decades. This is the fast-feedback or Charney sensitivity. James Hansen is also concerned about the long-term sensitivity. That is much more difficult to answer with climate models. Some of the relevant feedbacks are not in the models (a NCAR GCM scientist told me this), e.g. permafrost thawing. Hansen therefore turns to the paleo record to estimate both the Charney sensitivity and the long-term sensitivity. Hansen’s conclusion is the Charney sensitivity is essentially what is in the GCMs, and the long-term sensitivity is approximately twice that. I believe Joe agrees on this, but you’ll have to ask him to know for sure.

    So I think rather than disputing the IPCC, Joe is trying to investigate areas in which the IPCC is reluctant to tread. It is no wonder they are reluctant; even when they get it right, they are accused. Imagine if they actually got something wrong…

  19. Peter Wood says:

    Looks like Antarctica will have “seven Manhattans” less albedo quite soon.

  20. paulm says:

    Joe,
    Can we get an article/blog about tipping points and what are the options depending on where were at. I think there is much confusion amongst the lay person on what the situation is and what happens when we go past one – are there appropriate responses? We need to formulate long term plans depending on each point…

  21. Joe says:

    Paulm — I’ll see what I can do.