Satellite data stunner: “Our data suggest that EAST Antarctica is losing mass…. Antarctica may soon be contributing significantly more to global sea-level rise.”

Posted on

"Satellite data stunner: “Our data suggest that EAST Antarctica is losing mass…. Antarctica may soon be contributing significantly more to global sea-level rise.”"

The East Antarctic ice sheet has been losing mass for the last three years, according to an analysis of data from a gravity-measuring satellite mission.

That’s from the BBC storyNature Geoscience just published the study online, “Accelerated Antarctic ice loss from satellite gravity measurements.”  It begins, “Accurate quantification of Antarctic ice-sheet mass balance and its contribution to global sea-level rise remains challenging, because in situ measurements over both space and time are sparse,” and it concludes:

Our results suggest that over the WAIS [West Antarctic ice sheet] (especially the ASE [Amundsen Sea Embayment]) there is accelerated ice loss since around 2005 and/or 2006, with the EAIS showing correlated changes of the same sign in this period, attributed to increased ice loss over EAIS coastal regions in recent years. Using a simple linear projection for the period 2006-2009, Antarctic ice loss rate can be as large as -220plusminus89 Gt yr-1. These new GRACE estimates, on average, are consistent with recent InSAR fluxes4 but, in contrast to previous estimates, they indicate that as a whole, Antarctica may soon be contributing significantly more to global sea-level rise.

East Antarctic ice - graphicThe accelerated ice loss in WAIS is not a surprise to CP readers — see Nature: “Dynamic thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized.” Nor is the rapid loss at the ASE — the big blue blot in the figure [click to enlarge] — see 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.”

But ice loss in the East Antarctic ice sheet is definitely unexpected — the study leader Jianli Chen from the Centre for Space Research at the University of Texas in Austin told the BBC, “We felt surprised to see this change in East Antarctica.”

And it’s especially worrisome because EAIS contains vastly more ice than Greenland or WAIS:

The data comes from Nasa’s Gravity Recovery and Climate Experiment (Grace) mission.

Grace has previously shown that the smaller West Antarctic and Greenland ice sheets are losing mass.

These two bodies of ice contain enough water to raise sea levels by about six to seven metres (20ft) each if they melted completely.

Melting the East Antarctic sheet would raise sea levels by much more — about 50-60m.

But scientists have generally discounted the possibility of it happening because the region is so cold.

Not any more.

The media and others keep repeating the IPCC’s outdated sea level rise projections, which were based on data that is now several years old, even thoughmany recent studies (see below) suggest the IPCC has significantly underestimated likely SLR this century on our current emissions path.

Artist's impression of Grace satellite in orbitThe whole BBC piece is worth reading to understand the “tricky issue” involved in measuring Antarctic ice loss; the Grace satellite is depicted in the image.  And Australian reporter Jennifer Macey has an excellent interview with Nathan Bindoff, professor in physical oceanography at the Antarctic Climate Ecosystems Cooperative research centre in Hobart, that sheds light on the new study:

BINDOFF: Every new estimate of the contribution of Antarctica to sea level rise has actually grown over the last four to five years and what that’s really telling us is, that our state of knowledge about Antarctica isn’t as good as we would like and it’s becoming clearer to us that there is a very significant risk of quite large sea level contributions into the future….

MACEY: Professor Nathan Bindoff says the new research shows that region is more sensitive to a changing climate than previously thought.  And he says the 2007 IPCC report has underestimated the extent of future sea level rise caused by thinning ice in Antarctica.

NATHAN BINDOFF: And as we actually observe Antarctica literally shrinking in front of us, we understand that our estimates of that 22 centimetres from the ice sheets, Antarctica and a Greenland is almost certainly an underestimate.

And so the new numbers that people are extrapolating from these measurements, so it is a bit of an extrapolation, that what they’re saying is that there could be something like a metre to 1.5 metres for all of the contributions to sea level by 2100.

That is, unfortunately, becoming the mainstream projection in the scientific literature — see Startling new sea level rise research: “Most likely” 0.8 to 2.0 meters by 2100. While that 2008 study is often seen as definitive, it projects under 15 cm (6 inches) of SLR from Antarctica in its 0.8 m case and 62 cm (2 feet) in its 2.0 m case.  Yet WAIS alone could exceed that, see “Q: How much can West Antarctica plausibly contribute to sea level rise by 2100?” [A:  3 to 5 feet].

A 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).

And don’t forget this 2009 study — Nature sea level rise shocker: Coral fossils suggest “catastrophic increase of more than 5 centimetres per year over a 50-year stretch is possible.” Lead author warns, “This could happen again.” And this one, too — High Water: Greenland ice sheet melting faster than expected and could raise East Coast sea levels an extra 20 inches by 2100 “” to more than 6 feet.”

Did I mention the time to act is now!

http://climateprogress.org/wp-content/uploads/2009/11/EAS.gif

Tags:

« »

16 Responses to Satellite data stunner: “Our data suggest that EAST Antarctica is losing mass…. Antarctica may soon be contributing significantly more to global sea-level rise.”

  1. Steve Bloom says:

    Minor nit: I don’t think there was a general view that Pfeffer et al was definitive even when it was first published.

  2. MarkB says:

    There have definitely been enough studies now that should raise the mean IPCC estimate and range for sea level rise over this century.

    While the West Antarctic ice sheet is clearly unstable and contributing to sea level rise, the East Antarctic has generally been considered to be stable, with some estimates indicating it’s growing slightly due to increased precipitation (although not enough to offset the big losses in the west). This study is in contrast to the current mainstream view, and also in contrast with what some models indicate will happen over this century in that region, so some healthy skeptism is a good idea. The situation will have to be monitored closely.

  3. BBHY says:

    The news just keeps getting worse and worse almost daily.

    And yet, a recent article on climate on HuffPo is absolutely filled with comments about global cooling and matter-of-fact statements about how Antarctic ice is growing.

    The climate reality and the climate understanding of much of the public are diverging so much they are a full 180 degrees apart.

  4. ken levenson says:

    A few thoughts:

    1. Time to get temperature readings for Antarctica because it is warming!
    2. With Antarctica warming, aren’t current global warming assumptions low? (Imagine if it is warming anything like the arctic!)
    3. Why are ocean rise projections always revised up in a linear manner?! If less than a meter was projected 5 years ago and 1.5 meters was projected two years ago and up to 5 feet was projected in the last year – each time extrapolating seemingly in a linear way – when do we realize that the melting is not linear but growing geometrically???? While an extreme take-away, it seems that a more likely scenario given the acceleration we are seeing AT THIS EARLY STAGE, we’ll be projecting 10 feet in another year, 20 feet a year after that and 40 feet a few years later still….how soon will it seem perfectly reasonable that we could get 50 feet rise by 2100?
    4. At this point my bet is on 25 feet by 2100. (8 from Greenland, 10 from WAIS and 7 from EAIS) Depressing.

  5. Lou Grinzo says:

    Once again, we’re dealing with two critical information gaps:

    1. The gap between reality and what scientists know. This is NOT in any way meant to be a criticism of climate scientists, merely a recognition that we set a lot of things in motion before science was up to speed, so we’re now scrambling to close that gap. And the steady thrum of “it’s worse than we thought” stories should tell us that not only are we behind the curve, but we don’t even know how far behind we are.

    2. The gap between what scientists know and what law makers and voters/consumers know. Ask yourself how many of your non-environment geek friends know about even 1% of the things we talk about online, and how much a regular visit to the usual sites would change their consumption and voting patterns.

    It will take one heck of an effort to keep us from suffering immense climate impacts thanks to nothing more than ignorance.

  6. Wonhyo says:

    In 2001 research, the major ice masses were expected to remain stable for over 100 years. As JR points out in another article, scientists tend to understate climate change in their publications. Is it any surprise that that the reality is much more urgent?

    We need to target zero carbon emissions, now. Then we need to work out sucking existing GHGs out of the atmosphere. If we ramped up to a WWII scale effort, I don’t see why would couldn’t reach near-zero emissions by 2020. In the meantime, with a massive, global reforestation effort, we can start sucking GHGs out of the atmosphere.

    We need to get on this.

  7. Wonhyo says:

    “Satellite data stunner”?

    Any regular reader of CP (or any other informative climate science publication) should not be stunned at all about the EAIS melting. It would be naive faith in ignorance to assume that this mass of ice would remain, in isolation of all the warming and melting going on around it.

    We need to be targeting much deeper cuts in GHG emissions and embarking on a WWII scale of commitment to minimize further climate change.

  8. WAG says:

    I can predict how deniers will spin this:

    “Antarctic ice loss happening faster than expected? Yet more evidence the models are wrong!”

  9. johne says:

    When reading this and wondering what can be done to avoid the wars coming when massive populations have to relocate (think Bangladesh), and the costs of protecting California, New York, Holland etc, I am tempted to revisit the calculations from the Sahara Forest/Desertec and Seawater Foundation projects. Massive amounts of seawater are diverted into man-made canals, evaporated and condensed as fresh water for farming, and some filling the great depressions in the Sahara, Ethiopia and Eritrea (and even the Saltern in the US), and the Dead Sea. Such projects have the ingredients for sustained development – fresh water, power and food. Yes, there are lots of questions but what’s the alternative?

  10. mauri pelto says:

    The output of icebergs from Antarctica making its presence felt further north. http://www.straitstimes.com/BreakingNews/TechandScience/Story/STIStory_457985.html

  11. SecularAnimist says:

    I think it will be the “Hell” that gets us before the “High Water”.

    By the time that major coastal cities are being lost to rising seas, civilization as we know it will have long since succumbed to world-wide famine resulting from the global collapse of agriculture in the face of prolonged, intense, continent-wide mega-droughts — not to mention the imminent disappearance of the fresh water supplies for hundreds of millions of people.

  12. David Lewis says:

    Hansen, discussing how it was the last time Earth was a bit warmer than now:

    “the last time the world was 3 C warmer was a few million years ago during the middle Pleistocene and sea level then was 25 + or – 10 meters higher than it is now and that’s 80 feet and that’s something that obviously we don’t want to be headed in that direction”

    Hansen, on ice sheet disintegration: ”

    if we look at the last time an ice sheet disintegrated which was the Laurentide ice sheet in central Canada 14,700 years ago, and sea level then during meltwater pulse 1A, sea level went up 20 meters in 400 years so that’s 1 meter every twenty years so when an ice sheet disintegrates it can disintegrate very rapidly…”

    Hansen, on the ability of science to predict sea level rise due to disintegrating ice sheets:

    “this is a very nonlinear problem and maybe there’s going to be a big response even in a hundred years but we just can’t evaluate it”

  13. Barry says:

    Global ice meltdown is now occurring at the rate of 10 tons of ice lost for each 1 ton of ghg we emit.

    At least that is what my rough calculations show. The study says 220 Gt of ice loss per year from Antarctica. That is close to the level I’ve seen for Greenland annual ice loss too. Add a bit for mountain glaciers losses and the total is well over 400Gt per year.

    At that rate, each tank of gas is paired with a free ton or two of pristine sparkly fresh melt water. A jet-setting holiday can easily pack 50 or 100 tons of “ice-to-go” in with each passenger’s swimsuit.

    Hard to contemplate how much more damage we apparently need to inflict before we Americans and Canadians decide to do something meaningful about our almost 20 tons of ghg per person per year.

  14. Steve Bloom says:

    IMHO that’s a very effective way to look at things, Barry. Thanks.

  15. From Peru says:

    JR:What happened to my comment?

  16. PizKesch says:

    It seems to me that one gets even worse numbers from looking at the historical record.

    What are the chances of abrupt (centuries) climate change such as outlined in Kienast, 2003: “About 14,000 years ago sea levels rose 20m in 400 years. 1m every 20 years on average.”

    James Hansen in “Target Atmospheric CO2: Where Should Humanity Aim?”
    seems to say that at 450ppm CO2, the equilibrium response would be an ice-free planet. How long would this take?