Research casts alarming light on decline of West Antarctic glaciers

Dec 9, 2014

David L. Griffin

By Chris Mooney and Joby Warrick

For two decades, scientists have kept a close watch on a vast, icebound corner of West Antarctica that is undergoing a historic thaw. Climate experts have predicted that, centuries from now, the region’s mile-thick ice sheet could collapse and raise sea levels as much as 11 feet.

Now, new evidence is causing concern that the collapse could happen faster than anyone thought. New scientific studies this week have shed light on the speed and the mechanics of West Antarctic melting, documenting an acceleration that, if it continues, could have major effects on coastal cities worldwide.

Twin papers this week show that the rate of ice loss from West Antarctica is increasing — with the acceleration particularly pronounced in the past decade — and also why this is happening: Warmer ocean waters are pushing up from below and bathing the base of the ice sheet.

The findings add to a growing body of evidence suggesting that the effects of climate change are outpacing scientific predictions, driven in part, scientists say, by soaring levels of greenhouse gases in the atmosphere.

It often has been speculated that West Antarctica may be the most unstable of the world’s great ice sheets, a group that also includes the still-larger Greenland and the massive East Antarctica. And research published in May suggested that for the oceanfront glaciers of West Antarctica, held in place by moorings at the seafloor, a point of no return already may have been reached.


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19 comments on “Research casts alarming light on decline of West Antarctic glaciers

  • At the risk of being accused of double posting, to which I will plead guilty, I put this up on the “World’s hottest year yet thread, but by the time I did so, it would have been below the radar of most. It is more timely here, the italics are my original post, and the general link leads in turn to others more detailed.

    For interest on the topic in general, and a little more grist for the deniers to worry about, although the “I’ve made up my mind, don’t confuse me with facts,” school of logic appears to apply, I ran across this at the World Maritime News website. WMN and the marine community in general are hardly in denial, and are actively planning for the day the the NW passage and the Russian Northern passage are routinely open.

    The headline is: “West Antarctic Melt Rate tripled in past decade.”

    http://worldmaritimenews.com/archives/145693/west-antarctic-melt-rate-tripled-in-last-decade/?utm_source=emark&utm_medium=email&utm_campaign=Daily%20update%20World%20Maritime%20News%2C%202014-12-05&uid=2948



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  • It is too bad everyone has a self-defrosting fridge nowadays. Back in the 1950s, everyone was aware of the way when you manually defrosted a fridge, nothing seemed to happen much for a long while, then suddenly the ice would start falling off in great hunks.



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  • Roedy Dec 10, 2014 at 12:29 am

    It is too bad everyone has a self-defrosting fridge nowadays. Back in the 1950s, everyone was aware of the way when you manually defrosted a fridge, nothing seemed to happen much for a long while, then suddenly the ice would start falling off in great hunks.

    Not only that, but when you switch on a kettle it does not immediately belch steam!



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  • It said Australia’s conservative government had kept its election promises to reverse a number of climate policies.

    No surprises there, mind you, these are pretty much the only election promises that it has kept. For interested Australians, and others, Sally MacManus (google “tracking Abbott’s wreckage,”) has an ongoing list of broken promises (a long list) and general calumnies, right wing rhetoric, porkies, (abbreviated rhyming slang) and utter absurdities.

    Witness the Minister of Finance who said that a rise in fuel tax would not affect the poor because “They don’t have cars.”

    My daughters in Canada tell me that the arch conservative and god bothering Stephen Harper is also marching in lock step with the Murdoch press, Abbott, and the similarly intellectually challenged in the GOP. It is difficult to see the end of fundamentalism, our own in the West, as well as that in the East.

    Looking for a common denominator? In all current cases it is religion, being used for it’s own ends, and to justify greater restriction on free will for those who do not stay in step.



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  • 8
    inquisador says:

    And you can accelerate the pace of defrosting with the use of a hand-held hairdryer, in the same way that rising global air temperatures may work on the ice shelves.



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  • This isn’t the best analogy. The WAIS isn’t actually melting much, and atmospheric warming doesn’t have much of a direct influence. What’s happening is that basal melting due warm ocean currents is reducing the friction between the glacier and the seabed, making the glacier flow more quickly into the sea. This is what’s causing the rapid thinning at, for example, Pine Island Glacier. It’s flow, not surface melting.
    A better analogy would be pouring warm water into the gap where the freezer ice meets the freezer wall. This will help to melt the ice at the join and the block of ice would fall off sooner.



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  • What is the volume of water contained in this ice shelf? The surface area of the world ocean is on the order of 360 million square kilometers. So, to raise global sea levels by 11 feet (0.0033528 km), you would need something on the order of 1.2 million cubic kilometers of water. Does this ice shelf contain that much water?



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  • Sean Dec 11, 2014 at 5:18 pm

    What is the volume of water contained in this ice shelf? The surface area of the world ocean is on the order of 360 million square kilometers. So, to raise global sea levels by 11 feet (0.0033528 km), you would need something on the order of 1.2 million cubic kilometers of water. Does this ice shelf contain that much water?

    The National Geographic looked at all the ice sheets:-

    http://news.nationalgeographic.com/news/2013/09/130913-rising-seas-cover-september-statue-liberty-climate-change-global-warming/

    .On the September cover, the Statue of Liberty stands in water up to her midsection, where the label “NO ICE” marks how high the sea would rise on the American icon if all the ice on Earth melted.

    The cover story, “Rising Seas,” looks ahead to 2100 and the effects that higher sea levels caused by climate change might have on our coastlines.

    The world’s ice won’t have come close to disappearing by 2100. According to some scientists, that won’t happen for at least 5,000 years, and we’d have to burn through the planet’s supply of coal, oil, and gas to make it happen.

    But for the image on the cover (and for the pull-out poster accompanying the story), we wanted to explore what the world would look like if all the ice melted. Bill Marr, the magazine’s creative director, decided that the best way to illustrate this extreme scenario would be to use a recognizable point of reference: the Statue of Liberty. Nick Kaloterakis was recruited to create the art.

    The first question, of course, was how high the seas would rise on an ice-free planet. That answer was straightforward enough. Philippe Huybrechts of Vrije Universiteit Brussel projected a total sea-level rise of 216 feet (66 meters) should the entire cryosphere melt, including the behemoth East Antarctic ice sheet.



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  • Thank you for the information. I was curious because the article didn’t mention just how much water was trapped in the ice shelf.



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  • It is estimated that the volume of the Antarctic ice sheet is about 25.4 million km3, and the WAIS contains just under 10% of this, or 2.2 million km3.[1] The weight of the ice has caused the underlying rock to sink by between 0.5 and 1 kilometres[2] in a process known as isostatic depression.

    The isostatic depression carries with it it’s own risk that is the alarming consequence of the loss of the coastal ice shelves.

    They prevent the incursion of oceanic water under the continental ice cap, depressed as it is well below sea level. If they are lost, and oceanic water does intrude under the ice cap, it will lift the land ice by simple hydrostatic pressure, increasing the gradient of the slope it moves down. It will slide faster, and the volume flowing into the ocean annually will increase.

    PS, anyone, help, how does one get the quoted content in the large blue italic font? I seem unable to do it.



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  • JC Sheepdog Dec 12, 2014 at 2:42 am

    PS, anyone, help, how does one get the quoted content in the large
    blue italic font? I seem unable to do it.

    Either highlight it, and click on the symbol between the globe and the { } on the tool-bar, or type > at the start of the lines. You can highlight subsections and click on the B symbol to emphasise further sub-ections.

    Leave blank line spaces before adding other text.



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  • Sean Dec 11, 2014 at 6:26 pm

    Thank you for the information. I was curious because the article didn’t mention just how much water was trapped in the ice shelf.

    These ice shelves are snagged at particular points, so the issue is that warm ocean currents can flow under them and melt them from below, allowing ice they are holding back on sloping land to slide into the sea. Great masses of this can then drift off northwards and melt.
    Much of the West Antarctic ice-cap is below sea-level, so West Antarctic could become a group of islands, with ocean currents flowing around them.



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  • And at the other pole. How come all the deniers are oddly mute when reports like these get published, again, from Maritime Reporter:

    Arctic Temperatures Still Rising

    A new report led by the U.S. National Oceanic and Atmospheric Administration (NOAA) shows that Arctic air temperatures continue to rise at more than twice the rate of global air temperatures, a phenomenon known as Arctic amplification.

    Increasing air and sea surface temperatures, declining reflectivity at the surface of the Greenland ice sheet, shrinking spring snow cover on land and summer ice on the ocean, and declining populations and health of some polar bear populations are among the observations released in the Arctic Report Card 2014.
    http://worldmaritimenews.com/archives/147929/arctic-temperatures-still-rising/?utm_source=emark&utm_medium=email&utm_campaign=Daily%20update%20World%20Maritime%20News%2C%202014-12-19&uid=2948



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  • Satellite mapping continues to develop, producing more and more detailed data.

    http://www.bbc.co.uk/news/science-environment-30399073

    .Nasa’s Orbiting Carbon Observatory (OCO-2) has returned its first global maps of the greenhouse gas CO2..

    The satellite was sent up in July to help pinpoint the key locations on the Earth’s surface where carbon dioxide is being emitted and absorbed.

    This should help scientists better understand how human activities are influencing the climate.

    The new maps contain only a few weeks of data in October and November, but demonstrate the promise of the mission.

    Clearly evident within the charts is the banding effect that describes how emitted gases are mixed by winds along latitudes rather than across them.

    Also apparent are the higher concentrations over South America and southern Africa. These are likely the result of biomass burning in these regions.

    It is possible to see spikes, too, on the eastern seaboard of the US and over China. These probably include the additional emissions of CO2 that come from industrialisation.



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