Antarctic Ice shelf collapse – "worse than we thought"

Researchers Provide Detailed Picture of Ice Loss Following Collapse of Antarctic Ice Shelves

An international team of researchers has combined data from multiple sources to provide the clearest account yet of how much glacial ice surges into the sea following the collapse of Antarctic ice shelves.

The work by researchers at the University of Maryland, Baltimore County (UMBC), the Laboratoire d’Etudes en Géophysique et Océanographie Spatiales, Centre National de la Recherche Scientifique at the University of Toulouse, France, and the University of Colorado’s National Snow and Ice Data Center, Boulder, Colo., details recent ice losses while promising to sharpen future predictions of further ice loss and sea level rise likely to result from ongoing changes along the Antarctic Peninsula.

disintegration of Larsen B ice shelf The Larsen B ice shelf began disintegrating around Jan. 31, 2002. Its eventual collapse into the Weddell Sea remains the largest in a series of Larsen ice shelf losses in recent decades, and a team of international scientists has now documented the continued glacier ice loss in the years following the dramatic event. NASA’s MODerate Imaging Spectroradiometer (MODIS) captured this image on Feb. 17, 2002. (Credit: MODIS, NASA’s Earth Observatory) › Larger image

“Not only do you get an initial loss of glacial ice when adjacent ice shelves collapse, but you get continued ice losses for many years — even decades — to come,” says Christopher Shuman, a researcher at UMBC’s Joint Center for Earth Systems Technology (JCET) at NASA’s Goddard Space Flight Center, Greenbelt, Md. Shuman is lead author of the study published online July 25 in the Journal of Glaciology. “This further demonstrates how important ice shelves are to Antarctic glaciers.”

An ice shelf is a thick floating tongue of ice, fed by a tributary glacier, extending into the sea off a land mass. Previous research showed that the recent collapse of several ice shelves in Antarctica led to acceleration of the glaciers that feed into them. Combining satellite data from NASA and the French space agency CNES, along with measurements collected during aircraft missions similar to ongoing NASA IceBridge flights, Shuman, Etienne Berthier, of the University of Toulouse, and Ted Scambos, of the University of Colorado, produced detailed ice loss maps from 2001 to 2009 for the main tributary glaciers of the Larsen A and B ice shelves, which collapsed in 1995 and 2002, respectively.

'flyover' view of the Larsen Ice Shelf The Landsat Image Mosaic of Antarctica (LIMA) provides this “flyover” view of the Larsen Ice Shelf’s long reach out into the Weddell Sea. (Credit: LIMA)

› Larger image

“The approach we took drew on the strengths of each data source to produce the most complete picture yet of how these glaciers are changing,” Berthier said, noting that the study relied on easy access to remote sensing information provided by NASA and CNES. The team used data from NASA sources including the MODerate Imaging Spectroradiometer (MODIS) instruments and the Ice, Cloud and land Elevation Satellite (ICESat).

The analysis reveals rapid elevation decreases of more than 500 feet for some glaciers, and it puts the total ice loss from 2001 to 2006 squarely between the widely varying and less certain estimates produced using an approach that relies on assumptions about a glacier’s mass budget.

The authors’ analysis shows ice loss in the study area of at least 11.2 gigatons (11.2 billion tons) per year from 2001 to 2006. Their ongoing work shows ice loss from 2006 to 2010 was almost as large, averaging 10.2 gigatons (10.2 billion tons) per year.

An animation showing ice edge changes for the Larsen B ice shelf and its adjacent tributary glaciers can be viewed at http://svs.gsfc.nasa.gov/goto?3803.


Related Links

› Larsen B Ice Front Changes 2001-2009 (NASA SVS)

› Animation of Larsen B collapse (NASA Earth Observatory)

› Before and after Larsen A comparison (NASA SVS)


Goddard Release No. 11-046

=========================================================

UPDATE: The press liaison at NSDIC wrote to complain about  the “worse than we thought” title.

Dear Mr. Watts,

We noted that you republished a NASA/NSIDC press release regarding a new Journal of Glaciology paper. In the headline of your post, the phrase “worse than we thought” is in quotation marks. This makes it appear as if it is a quote from the press release, and a statement by the researchers. We request that you remove the quotation marks so that it is clearer that this is your headline.

NASA and NSIDC scientists are always willing to grant interviews to journalists if you have questions about their research.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Katherine Leitzell Science Communications National Snow and Ice Data Center Cooperative Institute for Research in Environmental Sciences 449 University of Colorado Boulder, CO 80309

I replied:

Dear Ms. Leitzell

The “worse than we thought” is a cliché that reverberates through the climate science community and is well understood by my readers. It is a satirical statement, intending to convey the oft repeated science by press release position that climate change is an escalating series of alarming press releases, each worse that the other.

Quotation marks also serve to delineate a satirical statement, and is often visualized in person by the person taking two fingers (index and middle) and bending them. It has also been described as being a snowclone in the vein of.

X is  “worse than we thought”.

Thus, since satire is protected by free speech, and this is a fair use application of a publicly funded study and press release, the headline stands. I will however make a footnote at the bottom of the story stating that NSIDC has complained, and the title are my satirical words. You should know that the press release is not being well received. http://tomnelson.blogspot.com/2011/07/antarctic-ice-allegedly-declining-at.html

Thank you for your consideration.

Anthony Watts

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Now it occurs to me that any protuding out far enough will break off eventually. What was expected? For it to just carry on growing indefinitely?

Adriana Ortiz

Just wait another 2 weeks we can really rub it in the AGW’s. Of course only trust Scandinavians when it comes to NH ice extent.
http://ocean.dmi.dk/arctic/icecover.uk.php
Looks like RC is putting its foot in mouth again LOL!
So Antarctica is melting????
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.recent.antarctic.png
Pleeuuuuzzz!
Even pro AGW CT can’t hide it

TomRude

FACT: The largest known ice island measured 31,000 km2 (335 km x 97 km) broke away from the Filchner Shelf in 1956 and was reported by the USS Glacier on November 12, 1956.
Larsen B-15 by comparison is 295 x 37 km.
EOM

As of today, 26 July, the area of Antractic Sea Ice is at its 1979 to 2000 average. If it’s losing it at the Larsen Ice Shelf then it must be gaining it elsewhere.

So, how much was the extent of the arctic ice in 1000AD?
If we don’t have an answer, then how do we know that the current state of affairs is not the natural astate of affairs?
GHG’s have nothing to do with it.
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming

SteveSadlov

Likely related to the nearby subduction zone.

But Global Warming is going to cause increased precipitation, which will cause the glaciers to flow faster, which will cause larger ice-shelves to build up and subsequently break off, which will raise the seas even more! I mean, everybody knows that the snow atop the glaciers isn’t from the ocean, right? The ocean isn’t made of snow!

This has been playing again on Cable (we’re doomed):
Last Days On Earth 10/12 History Channel (guess what is the #1 threat?)

So the ice loss has decreased by nearly 10 per cent in the period to 2010, compared with 2001 to 2006.
And that would be a problem how?

R. Gates

Accelerating Ice mass loss in both Antarctica and Greenland is undeniable. The only question is as to cause:
1) Natural cyclic behavior
2) Anthropogenic Warming
3) A combination of 1 & 2

Wayne Delbeke

Stark Dickflüssig says:
July 26, 2011 at 9:39 am
///////////////////////////////////////////////////////////
Increased precipitation indeed. So now that we have cubits and cubits of water lying in farmers fields all over North America replenishing ground water for the first time in 5 years, how much are the oceans going to drop leaving ports unaccessible? /sarc off

IIRC, the amount of ice loss they are estimating currently is equivalent to less than 1% of normal summer ice loss every year…

klem

11 billion tons sounds like alot but it is equal to 11 cubic kms of ice. The antarctic is coverd by 3 million cubic kms of ice. 11 kms is absolutly insignificant.
No matter how many gazzillion tons of ice has melted, the warmers always try to makee it sound so huge, but in reality the annual ice melt is nothing. It is so small, no wonder they have a hard time agreeing with the measurements.
Cheers.

klem

Excuse me, I made an error. Antarctica is covered by 30 million cubic kms of ice, sorry about that. The 11 cubic kms of melted ice is ever more insignificant than I had realized.

Latitude

Well, what made it get so dang big in the first place………duh

Greg from Spokane, Wa

Stark Dickflüssig says:
July 26, 2011 at 9:39 am
But Global Warming is going to cause increased precipitation… The ocean isn’t made of snow!
=========================
Heh. Thanks, I needed that. 🙂

Accelerating Ice mass loss in both Antarctica and Greenland is undemonstrated. The only question is as to cause:
1) Natural cyclic[al] behavio[u]r
2) Our models suck but they’re still right
3) A combination of 1 & 2
4) A combination of 1, 3, & 4
5) A combination of 4 and 2
6) All of the above except 1

Al Gored

OK. So what is this?
Science 22 July 2011:
Vol. 333 no. 6041 p. 401
DOI: 10.1126/science.333.6041.401
Antarctic Ice’s Future Still Mired in Its Murky Past
Richard A. Kerr
Summary
“A new reanalysis by two NASA scientists of the three standard ice-monitoring techniques slashes the estimated loss from East Antarctica, challenging the large, headline-grabbing losses reported lately for the continent as a whole. Although not the final word, the new study shows that researchers still have a lot to learn about the vast East Antarctic Ice Sheet.”
http://www.sciencemag.org/content/333/6041/401.summary?ref=topst

MikeEE

R. Gates
Accelerating Ice mass loss in both Antarctica and Greenland is undeniable.

Really? That’s news to all of us. Where is your evidence?

PajamaMan
Mike Jowsey

Watching NASA’s animation of the “collapse of the Larsen-B ice shelf”, this looks like cherry-picking. All the ice in the Bay looks to my untrained eye to be normal pack ice which comes and goes seasonally during the period of the animation 2001-2009. However, in 2001 there was a bit more of the sea ice and in 2009 a bit less. And this is a very localised event, not representative of Antarctica as a whole.
By the way, R Gates – Accelerating Ice mass loss in both Antarctica and Greenland is undeniable.
Check the stats before hyperventilating too much: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png
http://nsidc.org/data/seaice_index/images/daily_images/S_daily_extent_hires.png

So where are they rising sea levels, then?

Brian H

My advanced Toothpaste Model of sea ice represents the land ice as an open-topped cylinder containing and accumulating slow-flowing cold ice, and the bottom flange as an extrusion outlet where warmer faster-flowing ice gets squoze out. The faster it’s coming out, the higher the level of the cylinder’s ice must be.
So more calving proves there’s more land ice.
Q.E.D.
🙂

Athelstan.

Calving in the Antarctic…………. is news?
I mean we’ve had this ‘conversation’ before, the maritime influence! BUT, the freezing interior is getting colder… no weather stations and etc.
You know the type of stuff…….http://wattsupwiththat.com/2009/04/17/the-antarctic-wilkins-ice-shelf-collapse-media-recycles-photos-and-storylines-from-previous-years/
Shock horror and guess who’s come to tea? – NSIDC….glory be!

anticlimactic

I read some time ago that Larson B was a huge body of ice floating on water with a local anticyclone above it. I assume the air pressure was flexing this brittle material until it fractured and broke off. The removal of this ‘dam’ meant that glaciers would rapidly shed ice which was no longer blocked.
The ice shelf did not melt. It is not an unusual occurrence, in fact any large body of ice floating on water will eventually fracture without any ‘warming’.
Interesting, but no big story really.

dtbronzich

Watching a Glacier is just like watching the rapids of a great river, just in slow motion. If ice didn’t calf off from time to time, the ice would eventually close off the straits of Magellan.
Physically, this isn’t very different from loading up one end of a cheap paper plate with too much potato salad, eventually, something’s got to give. This is my usual philosophical answer, it does not require “proof”, it is open to ridicule, but understand that it is Philosophy, and is based purely upon observation, not modeling.

TedK

“Not only do you get an initial loss of glacial ice when adjacent ice shelves collapse, but you get continued ice losses for many years — even decades — to come,” says Christopher Shuman

And they know this how? Because of a 10 year (one decade) picture collage?

“Previous research showed that the recent collapse of several ice shelves in Antarctica led to acceleration of the glaciers that feed into them”

All right, so the glaciers accelerate… Prove the connection is solely based on the ice shelf breakup and not just seasonal AND prove it is unusual. Sure is not done in the press release..

“The authors’ analysis shows ice loss in the study area of at least 11.2 gigatons (11.2 billion tons) per year from 2001 to 2006. Their ongoing work shows ice loss from 2006 to 2010 was almost as large, averaging 10.2 gigatons (10.2 billion tons) per year”

My first thought, Enough data for a yearly estimated average, to be corrected over the next few decades/millenia. Not enough info to show these breakups are unusual. My second thought, from the summary it sure seems like they are convinced that entire ice shelf is glacier derived. So is this supposed ice loss calculated directly from glacier movement or is it just a supposition based on the shelf area breakups? Once again, the press releases trumpet alarums e.g. the ominous yet typically hollow “decades to come”, but give us very little detail depth.

Mark Wagner CPA

so far I’ve got:
Pajamaman 2
Rgates 0

mwhite

Antarctic Ice shelf collapse – “worse than we thought”
AGAIN!!!!!!!!!!!!!!!!!!!!!!!!!

Steve from Rockwood

Given an ice shelf is created by a growing ice sheet as it expands beyond the landmass and into the water (am I wrong here?) then would we not expect more ice shelf breakage as the ice sheet grows and expands. I think we should be worried only if these events (breaking ice sheets) ceased. This would be followed by a measurable reduction in the ice sheet thickness (no more expansion) and finally by measurable increases in the RATE of sea level rise.
Also, why the link between ice shelf calving and sea level rise when the shelf is in water already?
Finally:
“Previous research showed that the recent collapse of several ice shelves in Antarctica led to acceleration of the glaciers that feed into them.”
Isn’t this bass ackwards? Shouldn’t glacier acceleration lead to the collapse of more ice shelves as these are pushed further out into the sea?
I would fail a climate science test every time.

mwhite
Roger Knights

This paper is getting the Jeer Review it deserves.

Hector M.

Ice loss in West Antarctica has been occurring recently, but this does not mean that Antarctica as a whole is losing ice in net terms. Increased precipitation (which is supposed to increase with global warming) leads to faster ice formation on the whole continent, especially the vast central and eastern regions, amply making up for any losses in West Antarctica and the Antarctic Peninsula. The IPCC projects a net ice gain over Antarctica during the 21st century, thus detracting water from the sea and reducing the rate of sea level rise. Recent papers (such as Vaughan 2008 and his precedent papers: see refs below) review literature and present results that do not support the so-called Mercer hypothesis that West Antarctica ice shelf calving (and associated acceleration of land-based ice flow into the sea) has any relationship with global warming or SST.
References to Vaughan’s papers:
Vaughan, David G., & J.R. Spouge, 2002. Risk estimation of collapse of the West Antarctic ice sheet. Climatic Change 52:65-91.
Vaughan, David G., 2005. How does the Antarctic ice sheet affect sea level rise? Science, 308 (5730): 1877-1878. DOI: 10.1126/science.1114670.
Vaughan, David G., 2006. Recent trends in melting conditions on the Antarctic Peninsula and their implications for ice-sheet mass balance and sea level. Arctic, Antarctic, and Alpine Research, 38 (1):147-152.
Vaughan, David G., 2008. West Antarctic Ice Sheet collapse – the fall and rise of a paradigm. Climatic Change 91(1-2):65-79.

Hector M.

Steve,
“Isn’t this [backwards]? Shouldn’t glacier acceleration lead to the collapse of more ice shelves as these are pushed further out into the sea?”
From another apprentice in this matter:
Most of the West Antarctic land-grounded ice sheet is a marine ice sheet, resting on a continental bed located below sea level, and kept in its place (in part) by the surrounding (floating) ice shelves. The idea of a melting West Antarctica (originating with Mercer two or three decades ago) is that global warming would cause the shelves to melt; and that once the shelves dissolve into the sea, this would release the marine ice sheet from its bed and cause further acceleration of grounded ice towards the sea, with possibly positive feedback i.e. increasing rate of melting. This hypothesis appears to have no grounds, and is not happening, according to existing literature (see my previous comment).

Brian H

When glaciers and ice sheets shrink, they do NOT do so by calving. They melt away from the face, and leave debris behind, and puddles like the Great Lakes.
More calving = more core ice sheet buildup.

R. Gates

PajamaMan et. al.,
Yes, ice has been accumulating in the INTERIOR of Greenland, and of course, long term ice core studies show that this is to be expected during periods of warmer temperatures:
See: http://rabbithole2.com/presentation/images2/ice_core/alley2000.gif
Warmer Oceans=more evaporation=heavier snowfall in winter
But taken as a whole, Greenland and Antarctica are losing ice faster than it is accumulating:
http://www.bloomberg.com/news/2011-03-09/ice-loss-accelerates-in-greenland-antarctica-nasa-study-finds.html
http://www.sciencedaily.com/releases/2011/01/110121144011.htm
http://www.theage.com.au/environment/climate-change/us-finds-massive-melt-at-greenland-ice-sheet-20110629-1gr2l.html
http://www.physorg.com/news/2011-01-greenland-ice-sheet-video.html
______
Mike Jowsey,
You need to understand the difference between sea ice and the continental glacial ice we’re referring to.
July 26, 2011 at 10:37 am

Douglas DC

Now wha thappens when you put ice into a drink- it cools the liquid.
now what could possibly happen if a big freakin’ piece of ice hits the
water?
Jes’ askin’

anticlimactic

If Klems figures are correct then 10.2 gigatons would represent a loss of Antarctic ice of 0.000034% per year.
Not the most apocalyptic scenario!

More gloom and doom anti-science as a foundation to demand more gloom and doom tax payer research to produce more gloom and doom what difference does it make research. Maybe when palm trees are growing on Antartica, and large hotels are racking in the cash via tourism, the gloomerdoomers can predict massive growing inescapable glaciers, once thought to be a thing of the past; poised to whipe us all from existance.
The only consistancy is the over study of the last ten to 100 years. My farming grandparents know more about the climate than most climatologists, who suddenly are abundant and still can’t predict the weather, let alone climate change.

Steve from Rockwood

@Hector M. Thanks for the comments and the references. A little more reading ahead for me!

Owen

Oh Gawd, yet another ‘the world is ending’ story. The never ending fear mongering is insane.

Hector M.

RGates,
it appears indeed that Greenland has been losing ice in net terms, at least in a few years around 2000, but not Antarctica. And the latter is not predicted to lose ice in net terms during the coming century or so. See the IPCC AR4 report, and related (more recent) literature.

Matt G

Melting ice causes the pressure of the glacier to decrease, so the flow towards the sea or away from the center slows down. Gaining ice increases the pressure of the glacier, so the flow towards the sea or away from the center speeds up. During winter when the glacier is locked up in sea ice the pressure increases in areas with further snow. The locked up sea ice can hold this further pressure over time until whats holding it up begins to become weak. This depends on especially how much the build up of snow mass is and how thick/large the sea ice is. During the summer when sea ice regularly retreats, the forces holding up this glacier become weak. This enables carving and/or collapses of the glacier as it weakens and/or becomes prone to warmer ocean water the further out it spreads over the years.
Retreating glaciers like observed in the Alps during the 19th century, were at the time advancing towards villages and people were getting very concerned. Warming occurred around the mid-19th century, the glaciers stopped advancing and were in fact retreating with patches of ice and debris remaining. Calving of ice only occurs when the glacier is advancing and this can fracture or break when the temperatures are well below zero centrigrade. Antarctica is not losing any ice that is not far from it’s coast. The West Antarctica shelve is well out from the coast and most of it in the sea. The calving/collapsing of parts of this glacier can’t rise sea levels while it is occuring already in the sea. The entire Antarctic continent in a radius excluding the Penisula, always remains below zero centrigrade even during Summer. (some areas get even more snow build up)
Winter temperatures are extremely cold at this time of year even on the coasts.
http://www.uni-koeln.de/math-nat-fak/geomet/meteo/winfos/synNNWWantarctis.gif

Dave

From an engineering perspective, I think ice shelves fail due to “fatigue” with the driving force being the tides. Ice shelves float on the open ocean yet they are at some point fixed to land. Thus, parts of it go up and down with the tide while other parts are immobile. This induces a lot of stress with the magnitude dependent upon how much moves up and down (i.e. how much of the shelf floats). This bending back and forth damages the ice over time and at some point it fractures, much like a paper clip that has been bent back and forth too many times. Seems kind of simple…

Chuck Nolan

BigBadBear says:
July 26, 2011 at 9:17 am
Now it occurs to me that any protuding out far enough will break off eventually. What was expected? For it to just carry on growing indefinitely?
————
No, I hope not and I’m glad to see it stop before it reaches the Arctic.

Kelvin Vaughan

dtbronzich says:
July 26, 2011 at 10:52 am
Watching a Glacier is just like watching the rapids of a great river, just in slow motion. If ice didn’t calf off from time to time, the ice would eventually close off the straits of Magellan.
Physically, this isn’t very different from loading up one end of a cheap paper plate with too much potato salad, eventually, something’s got to give. This is my usual philosophical answer, it does not require “proof”, it is open to ridicule, but understand that it is Philosophy, and is based purely upon observation, not modeling.
Ah you have discovered there ia a tipping point.

There seems to be quite the enthusiam that AGW is dead when this is ice mass balance in the negative from just one small part of Antartica. A 11.2 gt loss changing to 10.2 gt loss per year just off of the larsen ice shelf area is still substantial.
http://www.skepticalscience.com/antarctica-gaining-ice-intermediate.htm
The whole of Antartica is loosing between 100 to 300 gt per year. Most of it coming west Antartica.
http://en.wikipedia.org/wiki/Larsen_Ice_Shelf
The speed of Crane Glacier increased threefold after the collapse of the Larsen B and this is likely to be due to the removal of a buttressing effect of the ice shelf.[14] Recent data collected by an international team of investigators through satellite-based radar measurements suggests that the overall ice-sheet mass balance in Antarctica is increasingly negative.[15]
I can understand that you believe the warmists are wrong, there is a lot of evidence that the ice all over the world is in negative mass balance. That kind of evidence would support the instrumental temperature record.
http://en.wikipedia.org/wiki/Instrumental_temperature_record#Warmest_Decades
Adding more co2 to atmosphere is ignoring what you don’t want to look at. A warmer world.

Dave Wendt

One gigatonne of ice is about one cubic kilometer of ice, which, as others have pointed out, makes the numbers on ice loss look relatively insignificant in relation to the volumes of ice in Antarctica. However the real telling comparison is to the volume of the world’s oceans which is generally given as approx. 1.5 BiILLION km3. Given the 3800m avg depth of the the oceans, the extra vol. generated by the claimed losses would amount to a couple of tenths of a millimeter of GMSL.

John Trigge

As with most discussions regarding climate, we have all descended into school-yard taunts of “my scientists can beat up your scientists”, ‘Oh, yeah?”, etc, etc, etc with no chance of finding common ground or an agreed position.

Gneiss

Hector M writes,
“Recent papers (such as Vaughan 2008 and his precedent papers: see refs below) review literature and present results that do not support the so-called Mercer hypothesis that West Antarctica ice shelf calving (and associated acceleration of land-based ice flow into the sea) has any relationship with global warming or SST.”
Vaughn does “not support the so-called Mercer hypothesis”? Perhaps we read differently. From the most recent paper that you cite (Vaughn 2008), emphasis added:
West Antarctic Ice Sheet collapse – the fall and rise of a paradigm
David G. Vaughan, Climatic Change 2008
“Abstract
It is now almost 30 years since John Mercer (1978) first presented the idea that climate change could eventually cause a rapid deglaciation, or “collapse,” of a large part of the West Antarctic ice sheet (WAIS), raising world sea levels by 5 m and causing untold economic and social impacts. This idea, apparently simple and scientifically plausible, created a vision of the future, sufficiently alarming that it became a paradigm for a generation of researchers and provided an icon for the green movement. Through the 1990s, however, a lack of observational evidence for ongoing retreat in WAIS and improved understanding of the complex dynamics of ice streams meant that estimates of likelihood of collapse seemed to be diminishing. In the last few years, however, satellite studies over the relatively inaccessible Amundsen Sea sector of West Antarctica have shown clear evidence of ice sheet retreat showing all the features that might have been predicted for emergent collapse. These studies are re-invigorating the paradigm, albeit in a modified form, and debate about the future stability of WAIS. Since much of WAIS appears to be unchanging, it may, no longer be reasonable to suggest there is an imminent threat of a 5-m rise in sea level resulting from complete collapse of the West Antarctic ice sheet, but there is strong evidence that the Amundsen Sea embayment is changing rapidly. This area alone, contains the potential to raise sea level by around 1.5 m, but more importantly it seems likely that it could alter rapidly enough to make a significant addition to the rate of sea-level rise over coming two centuries. Furthermore, a plausible connection between contemporary climate change and the fate of the ice sheet appears to be developing.