Antarctic Ice shelf collapse – "worse than we thought"

More from Vaughn 2008 not rejecting the “so-called Mercer hypothesis”:
“Indeed, all of the elements of the positive-feedback cycle that would, according to Mercer, lead inexorably to collapse, have now been observed on Pine Island Glacier: thinning of the ice shelf, inland migration of the grounding line, acceleration of the main trunk of the glacier, and thinning rates on the interior basins. In short, if 30 years ago Mercer and his colleagues had described the changes they would have expected as diagnostic of emergent collapse, this is the list that they might have written. Furthermore, the recently observed changes are occurring in the area of WAIS – precisely the area considered to be most vulnerable to collapse. Mercer himself noted that unlike, the Weddell and Ross sea sectors which drain through ~500-km wide ice shelves, the Amundsen Sea sector has only narrow ice shelves that might provide less buffering against collapse. Also, the Amundsen Sea sector rests on a deep bed and comparatively little thinning would be required cause widespread floating of previously grounded ice sheet. The Amundsen Sea sector was, perhaps over-dramatically, described by Hughes (1981), as “the weak underbelly of West Antarctica”. At least from the presently available observational evidence, an emergent collapse of this portion of WAIS seems distinctly more likely, than it did just 5 years ago when IPCC began their last (the third) assessment.”

Consider the estimated 10 Gtonnes of Antarctic glacial ice loss per year. That sounds like a lot, doesn’t it? Well, it is. But take it in context. As klem pointed out earlier, that translates to 10 cubic km of meltwater. Spread that meltwater over the 360 million square km of ocean. All things being equal, those 10 Gtonnes per year would cause a rise in sea level of 0.3 cm — about 0.1 inch — per *century*.
It’s far less than the loss in Greenland glaciers, which has been estimated at 200 to 300 Gtonnes per year. And even that doesn’t add up to much sea level rise.

two things:
if you squeeze an ice cube with a c clamp it will melt faster and deform with additional pressure until it fractures.
there is an occurance where if a piece of metal has a tiny bit of the protective covering removed a bit of corrosion forms and moves away by the circumstances (for the engineers among us see fretting corrosion) this continues until the circumstances are changed or until a pocket is formed where the corrosion bits have gone away.
just for grits i wonder if there are large pockets between the lower surface of the ice and the ground that the glaciers are resting on that have “gone away” and are throwing the learned calculations off.
C

Assuming ice shelf breakup leads to faster glacial flow and a new ice shelf, then won’t the glacial flow decelerate again when the new shelf has formed? Presumably “all this has happened before and will happen again”, as they put it on TV’s “Battlestar Galactica” (the 21st Century version).
So this story is basically a big yawn.

Pretty impressive ice-making machine down there – keeps overflowing – someone should turn the compressor down a fraz so not so much unnecessary spillage occurs – who knows, those expensive tourist boats might end up doing a Titanic, and Greenpeace might be able to hide behind one to sneak up on Japanese fishing vessels.

Adriana Ortiz writes,
“Just wait another 2 weeks we can really rub it in the AGW’s.”
Help me out here, what do you predict that DMI graph will show in 2 weeks, so you can “really rub it in AGW’s”?
I don’t understand your other comments either, care to explain? I’ve looked at all the same graphs but apparently saw different things.
“Of course only trust Scandinavians when it comes to NH ice extent.”
Looks like RC is putting its foot in mouth again LOL!
So Antarctica is melting????
Pleeuuuuzzz!
Even pro AGW CT can’t hide i”
Personally, I predicted months ago on WUWT a NH extent minimum of 4.6. I’m still comfortable with that, What’s your guess?

John Trigge writes,
“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.”
Where do you see that on this thread? It seemed relatively civilized, with newer studies getting cited to supercede older, as happens in science.

R. Gates – thank you for adding nothing to my understanding, just a snide comment. Typical of a troll. You link to a bunch of alarmist press clippings, not peer-reviewed papers. The first has a couple of interesting points:

They warned their 2100 figure can’t be considered a projection because of “considerable uncertainty in future acceleration of ice sheet mass loss.”

Because the study covers less than 2 decades of data it is not at all surprising that this caveat is appended.

“That ice sheets will dominate future sea level rise is not surprising — they hold a lot more ice mass than mountain glaciers,” said Rignot, also a researcher at the University of California, Irvine. “What is surprising is this increased contribution by the ice sheets is already happening.”

So why is the rate of sea level rise decelerating? In his recent paper, P.J. Watson includes the following in his conclusion (emphasis mine):

The longest continuous Australasian records, Fremantle and Auckland, situated on the western and eastern periphery of the Oceania region, respectively, exhibit remarkably similar trends in the relative 20-year moving average water level time series after 1920. Both time series show a rise in mean sea level of approximately 120 mm between 1920 and 2000 with strong correlation (R2 ≥ 0.93) to fitted second-order polynomial trendlines that reflect a tendency toward a general slowing in the rise of mean sea level (or deceleration) over time on the order of 0.02–0.04 mm/y2. The Fort Denison water level time series after 1940 similarly reflects a decelerating trend in sea level rise at a rate of 0.04 mm/y2 based on a strongly correlated fit (R2 = 0.974) to the second-order polynomial function.
This decelerating trend was also evident in the detailed analysis of 25 U.S. tide gauge records longer than 80 years in length (Dean and Houston, pers. comm.) and a general 20th century deceleration, driven predominantly by the negative inflexions around 1960 evident in many global records, are well noted in the literature (Douglas, 1992; Holgate, 2007; Woodworth, 1990; Woodworth, Menédez, and Gehrels, pers. comm.).

@- Mike Jowsey says:
July 26, 2011 at 6:23 pm
“So why is the rate of sea level rise decelerating? In his recent paper, P.J. Watson includes the following in his conclusion (emphasis mine):”…
It might be unwise to give too much credence to the Watson paper. As others have already pointed out it has problems with the use of a 20yr moving average up to 2000. This largely removes any signal of acceleration after 1980 making the data inadequate for comparison with the satellite data which shows an acceleration since then.
Looking at the raw data from both the Watson and Houston & Dean papers shows a common pattern. A clear rise from ~1900 to 1950s, then stasis followed by another rise from the late 1970s.
This pattern of rise/flat/rise seems strangely familiar – it is of course a parallel with the temperature record. This is surely unsurprising, there is an obvious physical link between temperature and ocean volume both by expansion and melting land ice. All the mathturbation trying to match the data to complex mathematical functions – second order quadratics? It seems a little pointless when the best correlation is with the temperature record.

Let me get this straight.
NASA. The National Aeronautical & Space Association.
The Goddard Space Flight Center.
In a day when we mothball space shuttles, rather than build more….what the HELL does NASA and the GSFC have any business (and at the taxpayer’s expense) studying sea ice and glaciers?
Oh….right….they are trying to prove “Ice Shelf Collapses of My Grandchildren”. I get it now.
Will the old NASA and GFSC please stand up??
Chris
Norfolk, VA, USA

renewable guy says:
July 26, 2011 at 2:14 pm
Adding more co2 to atmosphere is ignoring what you don’t want to look at. A warmer world.
Oops, except for example, the existence of inconvenient facts such as the at least two divergences of atmospheric temperatures and atmospheric CO2 concentrations, the first being the increasing atmospheric temperatures starting well before the rise of CO2 concentrations, as per usual according to the ice core data, and the latest being the rise of CO2 concentrations without any increase in atmospheric temperatures over at least the past 15 yrs..
In other words, renewable man, using CO2 concentrations as a proxy for atmospheric temperatures turns out to be about as reliable as using Briffa’s and Mann’s tree rings.
Then there’s also the mere fact that the CO2=CAGW hypotheses have not yielded an empircally confirmed prediction yet, to say the least – with instead even the opposite empirical phenomenon having often occurred instead – nor indeed the production of any new climate, or now even weather event in need of any explanation via an invocation of the CO2=CAGW GCM “physics”.
Only according to Climate Science’s CO2=CAGW “method” can a complete abscence of evidence along with the existence of directly contradictory evidence be things which don’t throw its own “hypotheses” into at least the categorey of being of insignificant use, if not even extremely dubious as compared to the realities according to real scientific method and principle science – things which you don’t want to look at, renewable man.

Gates is DFAA – Desperate For Any Apocalypse
Far-fetched doesn’t begin to describe this bunch, pathetically rooting everywhere for any alleged ‘evidence’ that will convert the taxpaying sheep to True Believers.
Just remember Mr. R., Al Gore lies and Eagles Die, the new Sacrifical Lambs of Eco Death-Worship.
Windmills use 5 times the per-Watt load of cement, steel, and rare-earths than nuclear reactors, and they kill far more people every year than Chernobyl. They’ll never last long enough for energy-payback.
Damnable windmills annually slaughter more birds and bats than DDT or oil slicks ever dreamed of doing in a thousand years. Aren’t you Warmistas proud?
Big Climate has squandered over $100 Billion, robbed from innocent taxpayers, and all we got was slick propaganda-lies and gulled kindergardners.
You babble endlessly about hypothetical ‘tipping points’ while not even one actual tipping point in Earth’s past has ever been computer-modeled.
These same Lefties blindly promote social policies that have triggered a plethora of disastrous societal tipping points – illegitimacy, govt-dependance, fatherless gang members, job-destruction, capital flight, and a hyper-beaucracy that reaches out to stifle children’s lemonade-stands.
Amercia is nearly choked to death already, perhaps past salvaging.
The likes of Gates are willfully blind to to the social tsunamis unleashed by the vile Left, as they hopefully gaze blankly upon their hypothetical climate fantasies to rescue their mad statism.
We all feel sorry for you, dude. Get a life.