Loss of West Antarctic Glaciers Appears Unstoppable, Posing Long-Term Risks from Rising Seas to Millions

By Tom Yulsman | May 13, 2014 1:04 pm
unstoppable

A screenshot from an interactive tool showing what Boston would look like with the 10 feet of sea level rise that would occur if the entire West Antarctic Ice Sheet were to disintegrate. (Source: Climate Central)

See a correction and update below. May 13 7:15 p.m. MDT |

If you read ImaGeo regularly, you may have seen my post a couple of weeks ago describing evidence that part of the West Antarctic Ice Sheet may be breaking up.

Yesterday, two additional studies were made public. One was led by Eric Rignot, a glaciologist at the University of California, Irvine, who had this to say at a NASA press conference: “Today we present observational evidence that a large sector of the West Antarctic ice sheet has gone into irreversible retreat. It has passed the point of no return.”

The likely cause: human-caused warming of the climate system. Update: I’m doing further reporting on this for a future post. Among other things, I’m looking at the role that natural variation of the climate system, and other factors, may be playing. More on that soon. |

The paper by Rignot and his colleagues, which examines the behavior of six West Antarctic glaciers that empty into a large indentation in the coast called the Amundsen Sea Embayment, has been accepted for publication in the journal Geophysical Research Letters. (Click here for a press release about the paper from the American Geophysical Union, publisher of the journal.)

Ian Joughin, a glaciologist at the University of Washington’s Applied Physics Laboratory, was lead author on the second study, which will appear in the May 16th issue of the journal Science. “There’s been a lot of speculation about the stability of marine ice sheets, and many scientists suspected that this kind of behavior is under way,” he says. “This study provides a more quantitative idea of the rates at which the collapse could take place.”

The sort of (but not really) good news: Joughin’s study suggests that while the early stages of what it refers to as “collapse” may have begun, the rapid stage of collapse would not begin until at least 200 years from now, and possibly more than a thousand years down the road, depending on the warming assumptions made. full disappearance of one of the six glaciers, the Thwaites Glacier, could take at least 200 years.

My colleague Andrew Revkin argues that given this time frame, use of the word “collapse” in this context, as some news outlets have done (for example, here), is a bit “overwrought.” I get the point: On a human timescale, 200 years or more for the start of rapid disintegration is a very long time indeed.

But on a geologic timescale, it is the blink of an eye. And that’s important to keep in mind too — that in a blazing flash, geologically speaking, we humans are managing to remake the life support systems of our entire planet. This is why I think today’s news will may eventually be seen as having historic significance.

Another key fact to keep in mind about the study by Joughin and his colleagues: Thwaites is a linchpin for the rest of the West Antarctic Ice Sheet, and its disappearance would likely trigger most if not all of the ice sheet to break up over a long period and flow into the sea.

That would raise sea level by more than 10 feet. The screenshot at the top of this post, from an excellent interactive mapping tool at Climate Central, shows what Boston would look like if the water were to come up that much.

Here’s what south Florida would look like like:

unstoppable

A screenshot from an interactive mapping tool by Climate Central shows what South Florida would look like with 10 feet of sea level rise. (Source: Climate Central)

In the United States, almost 5 million people live within just four feet of sea level today, according to the recently released National Climate Assessment.

Globally, hundreds of millions of people live in areas that would be inundated by 10 feet of sea level rise.

To understand how that amount of sea level rise could occur, check out the video above. It does good job of visualizing how the apparently unstoppable destabilization of a large portion of the West Antarctic Ice Sheet is now unfolding.

Taken together, the two new research papers, and the one I wrote about earlier, add up to this sobering picture:

  • The glaciers that drain West Antarctica are speeding up faster than expected, dumping ever increasing amounts of ice into the ocean, thereby raising sea level. (This was the subject of the research I wrote a couple of weeks ago.)
  • Warming waters circulating beneath the glaciers are thinning the ice. This is causing their grounding lines —  the points where they first lose contact with land as they flow out into the sea — to retreat inland. This, in turn, allows more water to circulate beneath the glaciers, contributing to thinning, and so on in a self-reinforcing process. (This comes from the paper by Rignot et al.)
  • Analysis of the bedrock beneath the glaciers shows there are no topographic features upstream of these grounding lines — no rocky hills, bumps, etc. — that could slow the glaciers and the retreat of their grounding lines. (Also from the Rignot paper.)
  • Lastly, Joughin and his colleagues used a combination of observations and modeling to show how long this self-reinforcing process would take to cause the Thwaites Glacier to drain into the ocean.
unstoppable

Photograph of the edge of the Thwaites Ice Shelf taken from a DC-8 aircraft on Oct. 16, 2012 as part of NASA’s Operation Ice Bridge project. The blue areas visible on the shelf edge are areas of denser, compressed ice. (Source: NASA Earth Observatory. Photograph by Jim Yungel)

Whether you believe yesterday’s news will be eventually be regarded as an historic moment or not, it is yet another clear sign that human-caused changes to the planet once regarded as theoretical are now very real.

And we should also be aware that the underlying geology and ice dynamics of the West Antarctic Ice Sheet are not unique. Yesterday I interviewed Jeremie Mouginot, a glaciologist at the University of California-Irvine and a co-author of the paper by Eric Rignot. He pointed out that while the much larger East Antarctic Ice Sheet is relatively stable right now and showing no signs of what’s happening in West Antarctica, “the same kind of behavior could eventually happen there.” 

Should that ice sheet become unglued, the challenge humanity would face from sea level rise would be unimaginably larger. Yes, we’d have a lot of time to plan for it. But do we really want to respond to the climate change impacts that are unfolding all around us simply by adapting?

I’m thinking of my kids as I write the following words: That would be tragically irresponsible.

  • FleetAngel

    Did we see this coming – the answer is a resounding YES!!!! As I have indicated before, we are past the tipping point and our children and grandchildren will have to live with the consequences of our excesses. Will we leave a legacy of a better world for them, the answer is a resounding NO. Lets see, a conservative estimate of a three to four foot rise in sea level by the end of the century means that New Orleans (where I live) will be a dead city and underwater in about another 75 years. A sobering thought, the billions spent on our new flood control systems will all have been for naught. If by chance we have another Katrina in the interregnum, the city will never have a chance to recover.

    • John Wyscaver

      If the city hadn’t been built in a bowl in the first place there really wouldn’t be a problem. Mother nature will work itself out. She always does, whether its with our help or not. The sea will always rise & fall & so will land masses. The thing people get but don’t want to hear is the earth is alive. Where just small creatures who don’t know better. Compared to us the earth is delicate & should be handled with care. That goes without saying but this whole ice melting thing, ice melts big surprise. The climate shifts reactions happen. but that doesn’t mean it was all from us. What be built will be destroyed one way or another. But the upside is what gets destroyed we rebuild & replace. So in a way your city won’t necessarily be destroyed & die but but will be rebuilt & shine once more. With that being said I know of a bunch of places there & in others down south & along the east coast that are in disarray & need to be tron down & rebuilt. So its not up to a governing body to get the job done but willing individuals with the proper skill set & others willing to learn that will get the job done.

    • disqus_atlq8Zmtsd

      Maybe if New Orleans weren’t already below sea level….

      • bobgeezer

        Duhh! What could possibly be wrong with building a major city below sea level?

        And they can’t even bury their dead properly.

        Whatever the reason or the cause, these are real problems and must be faced now: blaming them on anyone is just a political gambit to divert current attention from the long run problem, which is, of course, human emissions without regard to environmental consequences: a characteristic of Human Evolution for a millennium or more.

        • disqus_atlq8Zmtsd

          Agent Smith: A virus. Human beings are a disease, a cancer of this planet. You’re a plague

          • bobgeezer

            You’re right.

          • bobgeezer

            We humans are the plague – not me personally.

            We have destroyed 90% of living species since we arrived about 200,000 years ago. NOT the 99.9 % of all species since the beginning of all life on Earth: but 90% of the surviving species as of 200,000 years ago – a finger-snap in evolutionary History: and caused by the ascent of humans: that’s Us, Folks!

            Read “The Sixth Extinction” for proof.

  • http://blogs.discovermagazine.com Longmire

    Maybe in 50 years or so someone will find a way to melt the ice transport it further inland then let nature refreeze it, or even better yet evaporate it and transport it (within encapsulated clouds of course) to drought stricken land. Even if humans cant figure out solutions to our ever present demise our savior AI certainly will.

  • Ferdinand Marcos 2.0

    Good.

  • Fixer1

    The likely cause: human-caused warming of the climate system…this is what is utter BS. Sure the ice caps are melting, no denial there but the likely cause, us humans? Who was responsible then for the melting ice after all the previous ice ages? Man wasn’t even around then. Do some real scientific reporting and leave out the intended guilt tripping. It’s not working, is it?

    • bobgeezer

      I believe the primary cause is human caused emissions, BUT . . this post presents a very good question: what was responsible for prior Ice Age dissolutions? Maybe I’m wrong?

  • Buddy199

    Interesting but there are a lot of hypotheticals that have to be clarified before we hit the panic button. Either way, China and India are not going to stop their economic development because of something that might happen 200 to 1,000 years from now.

    • bwana

      How about the USA not being the world’s energy HOG!?

  • wangweilin

    No mention of the undersea volcanoes in the area.

  • Alan

    The rise in sea level will be only a minor part of the greater issue of more powerful storms, longer droughts, and a change in the overall flow of the jet streams resulting in drastically upended micro climates. Moving our coastal cities is one thing, but our much larger farming areas are going to have to be relocated too. In many cases, there won’t be anywhere to move them. 200 years isn’t enough time to allow forests to move. Soylent Green anyone?

  • bwana

    Humans are a lot like “deer in the headlights”. We’ll wait until the last moment to move… after it is too late!!

  • bobgeezer

    Let’s all forget who’s “to blame” and recognize that it’s here right now and will kill us all in a few decades. . . who cares about blame? IT IS HAPPENING – and it will kill us.

    Anyone have any intelligent ideas about preventing it? (Other than moving to Mars!)

    how about a solution in the average lifetime of the person participating in this exchange? a decade or two at the most? I’m 77; I don’t have 40 years, and frankly, I don’t care about solutions 100 years from now. No one has concern for people 3 or 4 generations beyond themselves – not really.

    Forget blame: solutions “now” or keep quiet.

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ImaGeo

ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.

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