From the Potsdam Institute for Climate Impact Research (PIK), home of Schnellenhuber.
Uncorking East Antarctica yields unstoppable sea-level rise
The melting of a rather small ice volume on East Antarctica’s shore could trigger a persistent ice discharge into the ocean, resulting in unstoppable sea-level rise for thousands of years to come. This is shown in a study now published in Nature Climate Change by scientists from the Potsdam Institute for Climate Impact Research (PIK). The findings are based on computer simulations of the Antarctic ice flow using improved data of the ground profile underneath the ice sheet.
“East Antarctica’s Wilkes Basin is like a bottle on a slant,” says lead-author Matthias Mengel, “once uncorked, it empties out.” The basin is the largest region of marine ice on rocky ground in East Antarctica. Currently a rim of ice at the coast holds the ice behind in place: like a cork holding back the content of a bottle. While the air over Antarctica remains cold, warming oceans can cause ice loss on the coast. Ice melting could make this relatively small cork disappear – once lost, this would trigger a long term sea-level rise of 300-400 centimeters. “The full sea-level rise would ultimately be up to 80 times bigger than the initial melting of the ice cork,” says co-author Anders Levermann.
“Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk,” says Levermann, who is head of PIK’s research area Global Adaptation Strategies and a lead-author of the sea-level change chapter of the most recent scientific assessment report by the Intergovernmental Panel on Climate Change, IPCC. This report, published in late September, projects Antarctica’s total sea level contribution to be up to 16 centimeters within this century. “If half of that ice loss occurred in the ice-cork region, then the discharge would begin. We have probably overestimated the stability of East Antarctica so far,” says Levermann.
Emitting greenhouse-gases could start uncontrollable ice-melt
Melting would make the grounding line retreat – this is where the ice on the continent meets the sea and starts to float. The rocky ground beneath the ice forms a huge inland sloping valley below sea-level. When the grounding line retreats from its current position on a ridge into the valley, the rim of the ice facing the ocean becomes higher than before. More ice is then pushed into the sea, eventually breaking off and melting. And the warmer it gets, the faster this happens.
Complete ice discharge from the affected region in East Antarctica takes five thousand to ten thousand years in the simulations. However, once started, the discharge would slowly but relentlessly continue until the whole basin is empty, even if climate warming stopped. “This is the underlying issue here”, says Matthias Mengel. “By emitting more and more greenhouse gases we might trigger responses now that we may not be able to stop in the future.” Such extensive sea level rise would change the face of planet Earth – coastal cities such as Mumbai, Tokyo or New York are likely to be at risk.
Article: Mengel, M., Levermann, A. (2014): Ice plug prevents irreversible discharge from East Antarctica. Nature Climate Change (online) [DOI: 10.1038/NCLIMATE2226]
Weblink to the article: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2226.html
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Meanwhile…back in reality
Antarctic Sea Ice Blows Away Records In April
By Paul Homewood
Antarctic sea ice continues to set new records, with extent in April at the highest since measurements began in 1979.
http://nsidc.org/data/seaice_index/index.html
Ice extent has also been above last year’s already high levels for most of this year.
http://nsidc.org/data/seaice_index/index.html
Meanwhile, both GISS surface and UAH satellite datasets show the Antarctic has been much colder than usual recently.
Full story:
I think they’re on to something. I can easily see an over abundance of southern icebergs rapidly headed north crashing into coral reefs, causing untold damage to litoral marine populations. Who cares about innundating coastal communities resulting from their melted remnants?
Okay. I’ll bite. For a study like this, one would need to know what the ground heat flux profile was under the glacier in question. I’ll assume they have drilled a few test cores to measure this, testing their assumptions.
“Now, if something isn’t done in the next couple thousand years ….”
These people are certainly making some preposterous assumptions about the greenhouse gas situation way beyond the next couple of decades.
Do they really believe we’ll be driving gasoline powered cars 1000 years from now? Or even 100 years from now? If so, why?
Why don’t we just build a REALLY big cork? Hey, I can be just as dumbass. Any day.
I can only hope that when the authors read the final draft of their paper – they laughed their collective asses off.
As far as I can see in the article the claim in the title to this thread was not made, despite the quotation marks:
Claim: ‘Emitting greenhouse-gases could start uncontrollable ice-melt’
Taking the extremes of this horrifying extinction event forecast, sea level (might) rise at a rate of 0.03 to 0.08 centimeters per year. Clearly, we (may) be doomed.
Melting would make the grounding line retreat – this is where the ice on the continent meets the sea and starts to float.
I wonder if he means like in the 19th century.
http://www.warwickhughes.com/climate/Iceberg.htm
In 1893 (after arriving in Nelson in September 92), the iron sailing ship “Margaret Galbraith” was homeward bound around Cape Horn. Mr. N.H. Burgess the 2nd Officer reported that from three days north of the Falklands to about one weeks sailing north of the Falklands they were “among the ice,” which culminated with a days sailing past a single giant berg “40 to 50 miles long,” The account suggest the ship may have been only making 3 to 5 knots around this time, certainly at night one would expect them to throttle back. They had a close call on first encountering the ice north of the Falklands.
It may be partly by chance that the length of this iceberg was reported because the sailing people seemed more impressed by the height of ice encountered than the extent of any particular piece. The 40 to 50 mile long berg mentioned above was reported as being 1000 ft asl at the NE end.
The 1000 ton plus iron sailing ship “Himalaya”, on a 109 day voyage from Liverpool to Wellington, departed 9, November 1894 and arrived 25, February, 1895. The captain reported seeing several icebergs off the Cape (of Good Hope) and then, “.. that from the Cape to the Crozets was a most trying time as icebergs were in sight for a distance of two thousand miles.”
Another reference to icebergs further north than “normal” is found in Basil Lubbock’s book, The Log of the “Cutty Sark”.
Starting on page 282 after recounting episodes on a voyage around Cape Horn in February when Cutty Sark encountered a large ice field (including icebergs ~20 miles long) starting north of the Falkland Islands at 50 degrees north.
there are enough weasel words in this to allow skipping of at least one year of law school….
The cork to the Wilkes Basin is where Godzilla lay frozen. If that cork melts it would change the face of planet earth.
The press release is a bit dumbed down.
This is actually an old theory. The idea is that the mass balance of an ice sheet depends on the difference between the accumulation of snow on top, and the surface area of the melt surface at the edges. If the two are constant, then the ice will either expand or contract at a fixed rate without ever stopping. They’re not constant, of course. As the ice sheet expands, its surface area increases, and therefore so does the snow accumulation. At the same time, the perimeter of the sheet expands and the height of the melt surface varies with the depth of water it is flowing into. If the water is getting deeper as you go further out from the shore, then the melt front increases rapidly in surface area and eventually grows to match the snow accumulation. If the water gets shallower as you move out from the shore, and the perimeter doesn’t change fast enough to compensate (a lot of models assume a constant width), then the situation becomes unstable, and either increases without stopping or decreases without stopping, until the geography at the edge changes.
And since there is a ridge out to sea off the Antarctic coast, it means that if the ice grounding line passes it there is the potential for the mass balance to become unstable. It depends on a bunch of other stuff, though. It assumes the precipitation on top of the ice sheet stays constant, that the horizontal length of the ice front is fixed, that the flow is uniform both spatially and over time, and no doubt some other stuff.
All this study appears to have done is put a new survey of the sea bed into a model and estimate how far the retreat would go. 3-4 m over 5000 years is about 1 mm/year, so I don’t think it’s anything to worry about, on its own. (Actually, it rather supports the anti-alarmist case, so we arguably ought to be applauding it…) And I think if Tokyo, New York, and Mumbai are still there in 5,000 years time, we’ll be doing rather well.
This has all turned into competitive science. My apocalypse is worse than your apocalypse. Well, at least it won’t wash out my golf game, I still have another 5,000 years to work on my swing.
http://www.coolantarctica.com/Bases/modern_antarctic_bases3.htm
The South Pole suffers less ice accumulation (60-80mm / 3″ per annum) than many places in Antarctica, but nonetheless there is constant addition to the level and no melt so buildings become buried over time. Wind blown snow forms drifts and tails around buildings, so the build-up can be significantly greater than the accumulation alone would imply.
cont……
The legs also allow for the whole building to be raised up to two more stories to stay clear of the snow surface in the future
Steve from Rockwood
May 5, 2014 at 10:15 am
says;
‘The cork to the Wilkes Basin is where Godzilla lay frozen. If that cork melts it would change the face of planet earth.’
Does that mean Godzilla really does exist? And, to counter that mythical creature, we should then go to an unelected, unaccountable, ravenous bureaucracy? And let that genie out of the bottle?
I don’t see the connection between the two parts of this post. In the first, they are not saying that warming in the Antarctic will trigger the flow of ice. Just as well as there is little evidence of warming. They say the trigger will be sea level rise, of which there is ample evidence for hundreds of years, though at a very slow rate.
Now back to the reality based world of observations.
Plus this
Another fact-filled article from the Journal of Geofantasy! The catastrophic demise of the East Antarctic ice sheet is not going to happen for a host of reasons, but two important ones should be enough.
1. The Antarctic ice sheet has not undergone this kind of demise since it first appeared in the Miocene, 15 million years ago. Throughout most of the Antarctic ice sheet history, global CO2 levels were 1000-2000 ppm (compared to present 400 ppm), so the miniscule rise of CO2 from ~300 to 400 ppm is an increase of only 0.010 % (peanuts compared to what it has been). So even doubling, tripling, quadrupling, or quintupling of CO2 would still be below the levels of most of the ice sheets history and the ice sheet survived those quite nicely.
2. An important reason why the Antarctic ice sheet isn’t melting (it’s actually growing!), is that Antarctica is encircled by clockwise atmospheric circulation around the entire continent that isolates it from the rest of the world. Take a look at http://earth.nullschool.net/#current/wind/surface/level/orthographic=-131.98,49.74,378
to see this circulation going on today.
So all the models in the world aren’t going to change the reality of the situation and are nothing but fantasy nonsense!
Back again to reality, just today we have report in that Antarctica sea ice hits a new record for this time of the year. It’s getting worse all the time as the evidence floods in. We will soon be submerged I tells ya. The end is nigh.
http://notalotofpeopleknowthat.wordpress.com/2014/05/04/antarctic-sea-ice-blows-away-records-in-april/
Der Speigel
http://notrickszone.com/2014/05/02/spiegel-on-antaractic-sea-ice-never-before-has-there-been-so-much-ice-at-this-time-of-year-since-meaurements-began/
I absolutely don;t understand why we publish any crap from Schellenhuber.
He get’s bonuses paid for all every article published on WUWT.
Just think how many forests we will have to grow and cut down to make a giant cork to solve this in the next 5,000 years! Worldwide employment and we can institute a global “cork tax”!
What could have caused this?
[Advanced apologies if I have made any typing errors as it is from an image.]
That’ll be another big steaming crock of the old ‘man-made global warming’ hooey, then.
I wish these chiefs would wind their neck in, it’s gotten really old and annoying.
Mind you, it’s not as annoying as the crapola about the 86% fall in snowpack in CA supposedly being the result of AGW.
These charlatans should be brought to book.
}:o(
” could start”
The entire alarm stands or falls on those two words. Even under the high emissions scenario, they are not sure that the ice “cork” would melt or that, once melted, the “bottle” would empty. And not just empty, but “start” to empty.
So much social and economic upheaval that is being justified on the basis of two simple words that are unprovable to be wrong or right. Amazing state the world is in: there is more actual threat deserving immediate action in an afternoon soap opera than in CAGW.
The effects of blocking the polar vortex in the vicinity of the magnetic pole are already visible in circulation over the southern polar circle.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_sh/500gz_anomalies_sh.gif
http://earth.nullschool.net/#current/wind/isobaric/10hPa/orthographic=123.63,-56.05,418
More snow, more ice, more melt, it’s getting crazy.