Exceeding critical temperature limits in the Southern Ocean may cause the collapse of ice sheets and a sharp rise in sea levels
![480px-Antarctica_6400px_from_Blue_Marble[1]](https://wattsupwiththat.files.wordpress.com/2014/05/480px-antarctica_6400px_from_blue_marble1.jpg?quality=83)
From the ALFRED WEGENER INSTITUTE, HELMHOLTZ CENTRE FOR POLAR AND MARINE RESEARCH and modeled certainty department:
Future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West Antarctic Ice Sheet. The result would be a rise in the global sea level by several metres. A collapse of the West Antarctic Ice Sheet may have occurred during the last interglacial period 125,000 years ago, a period when the polar surface temperature was around two degrees Celsius higher than today. This is the result of a series of model simulations which the researchers of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) have published online in the journalGeophysical Research Letters.
The Antarctic and Greenland are covered by ice sheets, which together store more than two thirds of the world’s freshwater. As temperatures rise, ice masses melt; in consequence the global sea level rises and threatens the coastal regions. According to scientific findings, the Antarctic already today contributes to the annual sea level rise with 0.4 millimetres. However, the most recent world climate assessment report (IPCC 2013) pointed out that the development of the ice masses in the Antarctic is not yet sufficiently understood. Climate modellers of the Alfred Wegener Institute have therefore analysed the changes to the Antarctic Ice Sheet in the last interglacial period and applied their findings to future projections.
“Both, for the last interglacial period around 125,000 years ago and for the future our study identifies critical temperature limits in the Southern Ocean: If the ocean temperature rises by more than two degrees Celsius compared with today, the marine-based West Antarctic Ice Sheet will be irreversibly lost. This will then lead to a significant Antarctic contribution to the sea level rise of some three to five metres”, explains AWI climate scientist Johannes Sutter. This rise, however, will only occur if climate change continues as it has up to now. The researchers make these assessments based on model simulations.
“Given a business-as-usual scenario of global warming, the collapse of the West Antarctic could proceed very rapidly and the West Antarctic ice masses could completely disappear within the next 1,000 years”, says Johannes Sutter, the study’s main author, who has just completed his doctoral thesis on this topic. “The core objective of the study is to understand the dynamics of the West Antarctic during the last interglacial period and the associated rise in sea level. It has been a mystery until now how the estimated sea level rise of a total of about seven metres came about during the last interglacial period. Because other studies indicate that Greenland alone could not have done it”, Prof Gerrit Lohmann, the head of the research project, adds.
The new findings on the dynamics of the ice sheet allow conclusions to be drawn about how the ice sheet might behave in the wake of global warming. According to model calculations, the ice masses shrink in two phases. The first phase leads to a retreat of the ice shelves, ice masses that float on the ocean in the coastal area of the Antarctic stabilising the major glacier systems of the West Antarctic. If the ice shelves are lost, the ice masses and glaciers of the hinterland accelerate and the ice flow into the oceans increases. As a result, the sea level rises, the grounding line retreats, leading to a further floatation of the grounded ice masses with a progressing acceleration and retreat of the glaciers. These will achieve a stable intermediate state only once – put simply – a mountain ridge under the ice temporarily slows down the retreat of the ice masses.
If the ocean temperature continues to rise or if the grounding line of the inland ice reaches a steeply ascending subsurface, then the glaciers will continue to retreat even if the initial stable intermediate state has been reached. Ultimately, this leads to a complete collapse of the West Antarctic Ice Sheet. “Two maxima are also apparent in the reconstructions of the sea level rise in the last interglacial period. The behaviour of the West Antarctic in our newly developed model could be the mechanistic explanation for this”, says a delighted Johannes Sutter.
The climate scientists used two models in their study. A climate model that includes various Earth system components such as atmosphere, oceans and vegetation, and a dynamic ice sheet model that includes all basic components of an ice sheet (floating ice shelves, grounded inland ice on the subsurface, the movement of the grounding line). Two different simulations were used with the climate model for the last interglacial period to feed the ice sheet model with all the necessary climate information.
“One reason for the considerable uncertainties when it comes to projecting the development of the sea level is that the ice sheet does not simply rest on the continent in steady state, but rather can be subject to dramatic changes”, according to the AWI climate scientists, emphasising the challenges involved in making good estimates. “Some feedback processes, such as between the ice shelf areas and the ocean underneath, have not yet been incorporated into the climate models. We at the AWI as well as other international groups are working on this full steam.” Improving our understanding of the systematic interaction between climate and ice sheets is crucial in order to answer one of the central questions of current climate research and for future generations: How steeply and, above all, how quickly can the sea level rise in the future?
###
Original paper:
Johannes Sutter, Paul Gierz, Klaus Grosfeld, Malte Thoma, Gerrit Lohmann: Ocean temperature thresholds for Last Interglacial West Antarctic Ice Sheet collapse. Geophysical Research Letters 2016. DOI: 10.1002/2016GL067818
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“says Johannes Sutter, the study’s main author, who has just completed his doctoral thesis on this topic.”
What? Send in the “A” team to do the research if we are all going to die. I don’t want someone just out of college. But at least he has been well educated on how to make money in the climate game.
…then comes the biggest word in climate science: “may”. Everything is an educated guess with them, tantamount to using the SWAG system.
Don’t forget “Could” and “Might” and “Possibly”.
” Everything is an educated guess”
I assume that in climate “science” the term “educated” is a technical term and has a different meaning to what it does in common parlance.
Don’t forget “Could” and “Might” and “Possibly”. be something to do with active Volcano’s under the ice and nothing to do with the climate. hmmm!
Well he might actually be correct that warming of the Southern Oceans might cause the collapse of the Antarctic ice sheets. Just think of all that extra weight of snow deposits on the Antarctic continent, with catastrophically increased evaporation from warmed southern oceans; what a collapse that might trigger.
But there’s a snag there in his thesis. Rising greenhouse gases; we’re talking CO2 here and that pesky methane, likely might warm the atmosphere, but thermodynamics would seem to dictate that that can’t transfer heat to the oceans; most likely the verse vicea would happen.
Warming of the oceans is done; when or if it is done, by the radiant energy from the sun, that gets absorbed in those deep oceans. And increased GHGs especially H2O, tends to reduce the amount of solar energy that even gets down to those ocean surfaces.
G
I guess this grad student should consider applying for his post doc fellowship right away, as his thesis doesn’t seem to have any great industrial market appeal, or value, so he could be heading into the unemployable class.
george, I don’t think their model makes any sense, but your claim that the atmosphere does not heat the oceans misses the entire mechanism on how the atmospheric greenhouse effect works. The atmosphere is not directly heating the ocean, but does still result in it warming due to decreasing the net radiation up. The effect of absorbed back radiation acts like a partial radiation resistance, and this radiation resistance is one component (along with convection, evapotransporation, the increase in average location of radiation to space and the lapse rate) of the warming. The problem with their models are many, including an assumed CO2 sensitivity and a thousand year linear slow increase in temperature, which have no basis at all.
They said, “… the marine-based West Antarctic Ice Sheet will be irreversibly lost”. Irreversibly … absolutely never to return.
It might take 1,000 years to go away, but it would be IRREVERSIBLY lost.
So no, they cannot in any way be assumed to be correct in their absolutist guess..
I’ve debunked dozens of these studies. These environmental studies students never incorporate real physics into their models, therefore the cooling effect of melting the ice almost never figures in their models. They as a consequence have NO IDEA how much energy it takes to melt 2 million cubic km of ice.
a great comment
Leonard Weinstein: “…but does still result in it warming due to decreasing the net radiation up…”
??? From a miniscule increase in lapse rate? In the few atmospheric IR windows not fully saturated with water vapor?
Given the speed of light, just how does a miniscule increase in apse rate become “decreasing net radiation”?
George, how do you expect them to get all that higher thermo stuff when they cannot even get this right -” As temperatures rise, ice masses melt; in consequence the global sea level rises and threatens the coastal regions. ”
No, ice does not melt until the temperature is over 0 C or 32 F. Even sublimation is more dependent – Sublimation occurs more readily when certain weather conditions are present, such as low relative humidity and dry winds. Sublimation also occurs more at higher altitudes, where the air pressure is less than at lower altitudes. Energy, such as strong sunlight, is also needed.
http://water.usgs.gov/edu/watercyclesublimation.html
Temperature still not mentioned.
Bobl – energy per KM^3 – http://wattsupwiththat.com/2015/06/03/el-nino-strengthens-the-pause-lengthens/#comment-1953030
4.13 x 10^17 joules / KM^3. What does that number represent? That is the energy it takes to convert one cubic kilometer of continental ice from -30 oC to water at 4 oC
“””””….. but thermodynamics would seem to dictate that that can’t transfer heat to the oceans; ……”””””
“”””””….. but your claim that the atmosphere does not heat the oceans misses the entire mechanism on how the atmospheric greenhouse effect works. …..””””
As you can see Leonard, I made no such claim that you assert.
The second law (of thermodynamics) prohibits a net transfer of ” HEAT ENERGY(noun) ” from a colder body (the atmosphere) to a warmer body (the non gaseous surface).
Clearly conduction, convection, evaporation, are transporting HEAT (thermal mechanical energy) from the solar heated surface to the cooler upper reaches of the atmosphere, and thermal radiant energy from the surface is also contributing that via the molecular resonances of green house gases, such as CO2, O3, and H2O, which comprise a small part of the atmosphere.
A net upward transport of HEAT, and additional warming energy from GHG radiation absorption spectra of GHGs.
Those heated atmosphere components are elevated by convection and removed from contact with the surface, and can’t convey net HEAT energy downward to the hotter surface.
Any radiant emissions (EM radiation) from those upper colder atmospheric gases, however generated, can of course partially propagate to the surface (< 50%) since the upward colder less dense atmosphere favors escape, whereas the downward warmer denser air favors recapture by atmospheric GHGs. So downward LWIR radiant energy from the upper colder atmosphere can certainly reach the surface and be partially absorbed, but more than 70% of that reaches a water surface, and at wavelengths that are strongly absorbed in the top few microns of that surface where they largely just result in increased evaporation.
I agree downward radiation can reach the surface, but a net downward transport of HEAT ENERGY (noun) is not possible.
“The researchers make these assessments based on model simulations.”
Did they mean assumptions? As in ” ass – u – me “
Shock and thaw!
+1
So, in summary…It’s worse than the other models say it is, so send us more money now !!! Only we can save you ( IF you give us more money ) !!
More money for settled science…//
What’s not to like?
The warming didn’t help this guy.http://www.bbc.com/news/uk-35398552
A thousand years out? When history shows a very great tendency towards cycles of warm and cold? What mechanism are they presupposing to eliminate that tendency? OMG CO2!
Plant food, so threatening!
To hysterics only.
“Given a business-as-usual scenario of global warming, the collapse of the West Antarctic could proceed very rapidly and the West Antarctic ice masses could completely disappear within the next 1,000 years”, says Johannes Sutter.
That’s great Johannes but this, ah, global warming you refer to – would you, um, have any evidence in support of that at all? Also it would be nice if there was some evidence that any climate modelling has enjoyed any level of skill to speak of before we all get too terrified by these new modeled results. Oh, and it appears that Antarctica is in fact seeing increasing ice mass and sea ice extent but I suppose that is irrelevant to the model.
“We at the AWI as well as other international groups are working on this full steam”
How reassuring!
Oh…and did we ever say the science was settled…no, not us!! We think we need to spend much more time postponing the understanding….refuting the consensus….no….confirming the consensus…no, wait…there is no consensus!!!!! CSIRO? What is that????
‘The CSIRO’s chief has told the ABC the backlash from his decision to restructure the organisation has made him feel like an “early climate scientist in the ’70s fighting against the oil lobby” and that there is so much emotion in the debate it almost “sounds more like religion than science”.’
http://www.abc.net.au/news/2016-02-11/csiro-boss-larry-marshall-defends-controversial-shake-up/7157650
Eh, back in 1965 the leading Warmists of the day predicted sea levels could be 10 feet higher by the year 2000 with full collapse of the Antarctic and Greenland ice by 2200.
I guess the world has received an 800 year reprieve.
Mercer, John H. “West Antarctic ice sheet and CO 2 greenhouse effect- A threat of disaster.” Nature 271.5643 (1978): 321-325.
700 citations!
Full Steam? Isn’t that a deadly greenhouse gas too? You think he would choose his words more carefully.
How the hell does this drivel-laden collection of conjectures pass critical review? Not only is it incomprehensible, it is based on a sort of GIGO-squared guess from the last interglacial. One that was two degrees warmer without a single coal-fired power plant in sight. Astounding….all the more so because robots like Obama quote this shytte as fact.
“How the hell does this drivel-laden collection of conjectures pass critical review?”
A thoroughly brainwashed and sympathetic press that is stuck on a narrative that has been fed to them since grade school is how all of this drivel passes critical review. The AGW propaganda (among other things) infiltrated our children’s classrooms and minds while none of us were paying attention.
Even if this is correct, a problem that may occur in a 1000 years time should be prioritised accordingly.
We didn’t expect William the Conqueror to deal with the Luftwaffe.
We shouldn’t try and use our technological resources to deal with this problem.
We have problems and responsibilities of our own.
Excellent point.
MCourtney,
“We didn’t expect William the Conqueror to deal with the Luftwaffe.”
That has my vote for Best of Thread winner! I’ll be using that (with due credit to you).
I’d tweak the quip to, “William the Conquerer couldn’t be expected to have plans to deal with the RAF”.
I’d say that is even better than saying: ” The Gattling gun is not backwards compatible with the long bow ! ”
Yeah, a gold star for MC.
G
therealnormanrogers,
The Courtney family traces our heritage in these isles only as far back as the Conquest.
My loyalty to the defence of the White Cliffs can only, reasonably, date back to then.
Just superb MC!
>”We didn’t expect William the Conqueror to deal with the Luftwaffe.”
That is the best line I have read in a long time. Kudos!
Beautifully put! This point is one I would love to see out there and in use a lot because it sums up the issues so perfectly. How pitiful our current attempts must be when put in proper perspective! I’m placing this argument at the top of my list. Thank you and +1000 on your comment.
But what if we caused it? Is there no moral duty to ameliorate it?
What if we didn’t cause ‘it?’ Where is the moral duty to ameliorate something that will not happen, so ‘it’ was not caused by us? Amelioration, as you call it, is extremely damaging to real lives … based on science that seems to be not at all well understood.
Dan, we have many moral duties but we do not have infinite resources.
For the sake of argument let’s assume that we are causing this problem.
Can you imagine the disgust with which our morality will be judged if we prioritised preventing the WAIS form collapsing in 1000 years time over providing clean water for the poor today.]
“We could fix that problem for nothing with our freezing satellites we had to get half a millennium ago. Of course, you primitives in the 21st century couldn’t have known we would have that. But you still could have spent your resources on problems you did know about”.
AGW is like eugenics and slavery.
Morally justified in the minds of the adherents.
But Indefensible through the lens of history.
AGW is like eugenics and slavery.
Morally justified in the minds of the adherents.
But Indefensible through the lens of history.
Wow. That is a profoundly stupid statement MCourtney. You have become your father.
Dan
A statement, no doubt. Now, why do “you” think it is a stupid statement, and why should “I” believe your opinion is correct?
Tell you what authors, the West Antarctic ice sheet is very considerably more stable than your jobs when even idiots like Camoron, Obama and similar work out how you’ve been hoodwinking them with such garbage non-science for the last generation.
Obama is paid NOT to figure that out.
“It is difficult to get a man to understand something if his salary depends upon his not understanding it.”
Upton Sinclair, 1878-1968
So, is the claim now there will be no exit from our current interglacial back to a full ice age again?
When they prove there is no ice age coming I’ll start to worry about CAGW.
After reading that l’m going to go to home depot and buy a bigger sump pump for the basement.
Feature not a bug. Real glaciation would be a much bigger problem than rising oceans. 15,000 years ago the place I am sitting at 40°N and 245m above msl, was covered by about 1500 m of ice.
It seems like it’s not the SUVs that is causing instability in West-Antarctica after all:
http://realclimatescience.com/2016/02/west-antarctic-fraud/
This is a link to a free access article in the Chicago Tribune that has more detail. http://archives.chicagotribune.com/1977/01/09/page/1/article/flood-threat-from-polar-ice
last section places this in context.
“Dr. George Denton, another University of Main glacial expert, recently has found evidence that the Ross shelf is rapidly disintegrating. …at one time the shelf extended all the way across the Ross Sea…and…was so thick that it rested on the sea floor.
Within the last 6,000 years, the shelf has shrunk and no longer rests on the sea bottom: it is now floating….The dome of the shelf was at least 1,300 feet higher about 30,000 years ago.”
So the context is that the West Antarctic ice has been decreasing for 30,000 years. Last time I checked, there was no evidence of SUVs that long ago.
“… during the last interglacial period 125,000 years ago, a period when the polar surface temperature was around two degrees Celsius higher than today…:
———————
Oh those poor souls, laying waste to Marcott 2013 (yet again.)
Are you saying that 125,000 years ago, the Antarctic highlands, only got down to -92 deg. C, instead of the -94 deg. C that they get down to today ??
g
Yes.
But it gets even worse… applying the climate science logic of ocean “acidification”, the highland ice would have been more liquid at -92 degrees than at -94 degrees and that’s where it’s heading again!
Ocean warming from increased CO2………mechanism and measurements , please …..
and model ” data ” does not mean shineola …
If it happened naturally during the previous interglacial, I see no reason why it could not happen even naturally during this interglacial. I think the best approach is to prepare to adapt.
The scientists in question talk about ‘collapse’. While in the geological sense, collapse might well describe something that lasts a millennium, linking this to AGW making up a CAGW scenario is kind of bullshit.
And no, I’m not a de-nier. The WAIS really ‘could’ collapse during the next 1000 years. And human GHGs ‘could’ play a role. But what comes to conclusions drawn by random green readers, GHGs are not the central problem, the central problem is we don’t know even how the interglacials would work without humans around. These scientists, I hope, have done good work in revealing the uncertainties around. It is just that coming to publicity means staying on message.
And apparently I can’t spell ‘thought’.
“f it happened naturally during the previous interglacial”
It probably didn’t. That “6-9 meters” figure is a factoid, i e something repeated so often that everybody thinks it is an established fact, while there is actually little real evidence for it and a great deal against it.
There are a fair number of stranded, last interglacial, reefs on what are thought to be “stable platforms”, e.g. Bahamas, Florida, Seychelles that are 6 to 8 meters above current sea level. It’s possible that there is no such thing as a stable platform, but it’s also possible that they exist and sea level really was 20ft or more above current the last time the planet was warm.
It’d probably be a good idea to allow for considerable sea level rise in the next ten centuries or so. Probably doesn’t matter where you put parking lots and marinas, but transportation tunnels, bridge approaches etc, might best be well up above current sea level, or at least hardenable if it turns out there is a problem.
Both the Bahamas and Florida are in the forebulge zone of the Laurentide Ice-sheet, and therefore useless to establish interglacial sea-levels.
It is extremely difficult, if not impossible to find a coast that has been stable at meter-level since the last interglacial, read this paper (and data in thre appendix):
https://perso.univ-rennes1.fr/laurent.husson/PAP/pedojaetal14.pdf
Henderson Island in the South Pacific? An atoll in the last interglacial.
To be fair, Marcott only covered the past 10,000 years, but the paper is used to prop up the “warmest year ever recorded” meme, which becomes ridiculous in light of evidence that the earth has undergone many eras warmer than present
@ur momisugly mods: this comment was supposed to be attached to my comment at 6:51am. Not sure why it didn’t-
[We’re not sure either. Sometimes WordPress does inexplicable things. -mod]
Only one slight problem!
Southern Ocean SSTs have been plumetting for the last 20 yrs
Paul: Indeed! I was just about to post exactly the same comment and chart 🙂
Ah, but the terrible heat is hiding deep in the ocean and undermining the ice!
Yes, seriously. This is actually the official “party line”.
My fellow Paul: Wait a minute, that chart isn’t even based on a climate model! Typical den*alist tactic, using data before NOAA has taken it to the “adjustment” room in the basement. Since we KNOW it’s warming, (it’s physics) showing this obviously biased data should get you thrown in jail (or at least to the “attitude adjustment” room. Bartender, another sarc. please.
I say we send these chaps to live in the center of Antarctica since it is going to melt. Give them all fishing poles so they can go catch their dinners there. They are NOT allowed to eat any Emperor Penguins!
Does “business as usual warming” mean RCP 8.5?
The weirdest thing about this constant yammering about imminent WAIS (West Antarctic Ice Sheet) collapse is that it is based on two premises that are never questioned:
1. The WAIS collapsed during the last interglacial.
2. Sea-level during the last interglacial was 6-9 meters higher than now.
However there is no real evidence at all for 1) and very little for 2).
We know for certain that West Antarctica did not deglaciate completely during the last interglacial since there is conclusive evidence for very extensive glaciation at that time in at least three widely separated areas (Marie Byrd Land, Ohio Range and Ellsworth Range). There is on the other hand not a shred of evidence that West Antarctica was ice free during the last interglacial. On the contrary oxygen isotope data from last interglacial ice om Mt Moulton indicates temperatures only marginally warmer than today and the ANDRILL-1B core indicates that the shelf ice in the Ross Sea was not appreciably smaller than today. Also there is not a trace of young marine deposits anywhere inland in West (or East) Antarctica.
But Antarctica isn’t warming.
But it will, it will, the models say so!
Exactly!! The Southern Ocean might need to stop cooling first – you would think – in any rational world. And two degrees in 125,000 years; for f%ck sake, what weren’t they thinking!
There is some ’trixy’ wording though:
Another case of the models that bear no relationship to reality proving what ever we want them to, please give us more of your tax money and be VERY FRIGHTENED, THE SKY IS FALLING!!
http://woodfortrees.org/graph/hadsst3sh/mean:120/from:1907.75
Since 1907, the southern oceans have warmed by ~0.8 °C. So, we have 275 years to prepare for the Gorebotic version of a Noachian Deluge.
Oddly enough, they were warming more rapidly before 1940 when atmospheric CO2 was “safely” below 350 ppm.
…the southern oceans have warmed by – 0.8 °C.
Which brings to mind George Orwell:
“Choco rations have been increased to 25 grams per week, up from 30 grams per week.”
(From the novel ‘1984’)
db, actually David’s post looks like a tilde.
lee,
You’re right, I should have looked closer.
Yet another climate model geofantasy! Did the authors bother to check their results against reality? Did the West Antarctic ice sheet collapse during the last interglacial (the basis for their model)? There is no evidence that the West Antarctic ice sheet has ever collapsed, even when temperatures there were higher than at present..
About a year ago, I looked into the situation and found that most of the West Antarctic ice sheet is thicker than the depth of its base below sea level, so it isn’t going to float and collapse suddenly, Geothermal heat is unusually high beneath the small part of the ice sheet that makes up the two small outlet glaciers cited as ‘collapsing’ (they aren’t), so it looks like that’s the reason for small increases in local calving of the two outlet glaciers. It certainly doesn’t have anything to do with global warming–satellite measurements show no warming in Antarctica in 37 years and surface temperature measurements at the South Pole and Vostock show no increase in temperature since 1957. As Paul Homewood points out in his post above, Southern Ocean SST has been declining for the past 20 years, not warming.
Consider what happened at the end of the Last Ice Age when gigantic ice sheets coving much of the northern latitudes melted under temperatures rising at rates of ~20 F per century. Sea level rose at rates of about a meter per century. The West Antarctic Ice Sheet makes up less than 10% of Antarctic ice, a puny amount relative to the huge ice sheets that melted suddenly at the end of the Pleistocene.
So much for yet another failed model study.
..These ” scientists ” seem to live on a different planet ( or maybe a virtual reality world )
Well all of the GCMs don’t model ANY real rotating planet, that actually is bathed continuously on its sunlit side by a TSI beam at an annual average rate of 1362-6 W/m^2, instead of a flat planet with a stationary sun above, that is at an annual average distance of 186 million miles, so it only generates a 341 W/m^2 average annual TSI, which isn’t enough to bring a BB equivalent temperature above 5 deg. C with a 0% planet albedo, or above 255 K with a 30% planet albedo, such as earth has.
The earth’s actual sunlit side insolation, with a 30% albedo, is heading for a BB equilibrium Temperature of 360 K at that sunlit region during the daylight hours.
Lucky for us, night falls, before it gets there.
G
…Ummm, that’s what I said !! LOL
Vostok has warmed at 0.16 deg C / decade since 1957, according to the Russians who run the place.
They should all get the hell out of there, before they all end up falling into the lake.
g
Future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West Antarctic Ice Sheet.
And I thought the local sub-aerial volcanoes had something to do with it.
It is correct that during the Eemian interglacial, sea level reached 6-7 meters higher than at present. This took about 3000 years, so was meltwater not ice sheet collapse. See Kopp 2009 in Nature for details. The main paper concluding otherwise, OLeary 2013 in Nature Geoscience, comprises a clear cut case of academic misconduct, specifically misrepresenting data. Essay By Land or by Sea. So these model results are BS.
If you believe AR1 thru AR5, and really, I see no reason not to, thermal expansion also plays a substantial role in 20th century sea level rise. That could easily continue even with the Sea Surface Temperature not changing much at all if surface warmth slowly works its way downward. It appears to me that the IPCC sea level folks still don’t have their sea level rise budget completely worked out. Neither do they seem to anxious to address the still substantial mismatch between tidal gauge and satellite measurements. Or maybe they do address it in AR5 and I missed it. AR5 is written in a rather opaque style.
SLR has two components: icesheet water, and thermosteric rise. The so called closure problem is that observed SLR dos not equal estimates of the two components. Depending on who does the calculation, off by 1/3 to 1/2. Essay PseudoPrecision goes into details.
With the mean annual temperature of the interior of Antarctica at −57 °C (−70.6 °F), I’m curious where all the melting is expected to come from. This temperature would have to increase by over 55°C to melt. Even the most aggressive models don’t show this level of warming.
They didn’t claim it melts there, they said it collapses, which refers to ice flowing down to sea, where it then can melt. If Eemian interglacial has SL 7m higher, I see absolutely no reason why it would not happen again. But it takes more than centuries.
And they might be wrong. It could be it won’t happen. We don’t have a full picture of this yet.
Look they say interglacial could be even 2K warmer naturally. And they didn’t take Zwally paper into account. We are still far from an unprecedented interglacial.
The men will be beaten for ‘giving ammunition to deniers’.
If the msl rises by 7m we will have to move to higher ground or build higher sea walls. OTOH, if it is over 1000 years, that means we will have to deal with a rise of 7 mm/yr. We ought to be able to do that at a slow walk. All structures that are now in place will be fully depreciated within 50 years so the loss of permanent capital due to ocean rises of about 350mm over that time period should be zero.
http://wattsupwiththat.com/2016/01/29/study-suggests-a-sea-level-climate-feedback-loop-in-the-mid-ocean-ridge-system-regulates-ice-ages/
Using this as a model…
Warm air is less dense than cold air, so perhaps the warmer lighter air isn’t putting as much pressure on the volcanoes under the ice sheets, causing more glacial melting, causing more ice to slide into the sea.
It makes as much sense as most of the arguments Warmists use to turn an upward trend of atmospheric CO2 into certain climate doom.
The melting is bottom up, and it’s always going on. What they’re suggesting is faster flow, with melting exceeding precipitation. Worst case: a thousand years to deal with what Long Beach had to deal with in 50. –AGF
They do the typical Warmist trick of saying that 2 degrees of atmospheric warming (which would still not raise Antarctic temps above freezing) will result in 2 degrees of ocean warming