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?
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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
We know that the modelled “business-as-usual” scenario drastically overstates the likely warming.
Even assuming this projection is right this is a problem for my 25*great-(at least!)grandchildren.
This likelihood is further into the future than William the Conqueror’s invasion of Enlgland is in the past!
When are these fools going to develop a sense of proportion?
I’m confused. Doesn’t “marine-based” mean ice that is already floating in the ocean? Melting of marine based ice does not raise sea level.
Rick, the two great WAIS ice shelves, Ronne and Ross, have a floating shelf portion, but the majority is grounded. The grounded portions could raise sea level if they shrank. But they aren’t.
Yes, but I don’t see where sea surface temperature rise (even if it actually happens) would do more than melt some of the sea ice. Since the year round temperature in Antarctica is well more than a couple degrees C below the freezing point, what causes the land ice to melt? Or is it all being held in place by the sea ice and will suddenly (over a period of 1000 yrs?) slide off into the Southern Ocean? Seems like pure speculation to me.
The ice melts iff it flows to the sea. Rising sea level will help that flow to some extent, but I would not bet on that happening too easily.
Well it actually lowers sea level, because most of that floating ice and its surface area is underneath the water, so the latent heat required to unfreeze all that ice, must come from the ocean water it is floating in, and not from the atmosphere. Melting one gram of floating ice can cool 80 grams of water by one deg. C, and since salt water has increasing density all the way down to its freezing point (no Temperature of maximum density) than the cooled ocean waters must shrink.
Of course it might also cool 800 grams of sea water by just 0.1 deg. C or it might cool 10 grams of sea water by 8 deg. C
This is really a one dimensional problem, if it is happening over a large surface area, so if the longitudinal coefficient of expansion of sea water is constant over that Temperature region, then the amount of sea level drop is quite independent of the distribution of that latent heat sourcing.
Cooling 10 times as thick a water column by one tenth of the Temperature delta produces exactly the same loss in sea level.
So melting sea floating ice causes the sea surface level to fall.
When I pointed this simple incontrovertible fact out, in a letter to ” Physics Today, ” a prominent AGW warmista responded that I was all wet (in effect), and my conjecture was nonsense.
I wrote that letter in response to a book review by a chap named (I think) Morrison, who I also believe is now deceased. He was reviewing a book; ” The Discovery of Global Warming. ” by an author named Spencer Weart.
It was Weart who pooh poohed my assertion that the sea level must fall, when floating sea ice melts.
It so happens, that he recently, in the same journal Physics Today, authored a rather lame response to another letter writer, who had also commented on another work by Weart. I think it is either the Jan or Feb 2016 issue of PT.
G
George, hasn’t that ice also already displaced its volume in the ocean and, and being 10% less dense than water, it would shrink the volume of the ocean, too.
Gary, I get where you are going, but I think maybe that isn’t so.
Let’s put any “cooling” of the ocean water aside for the moment, and just consider the floating ice.
9/10 or 10/11 of the ice is below the water. The remainder is up above the surface.
BUT …. 100% of the water in that floating ice just fits perfectly into the volume of the ice below the surface, once it liquefies.
So the ” hole ” in the ocean is just big enough to take ALL of the water in the floating ice.
That is simply the Archimedes principle.
But it is the cooling of a huge volume of sea water to supply the latent heat of melting the ice (80 calories per gram) that shrinks the ocean water and lowers the sea level due to the fact that sea water shrinks (increases in density) as the Temperature is lowered, all the way down to its freezing point (for sea water with even much lower salinity than ordinary ocean water.
So it is not like FRESH WATER that has a maximum density at 4 deg. C
G
I like Anthony’s quip “modeled certainty department”. That is exactly how it is. And there will be kudos and prizes to whoever can programme the supercomputers so that they come out with the desired answers. That is a sad state of affairs for a science foundation – and how ironic that this one is The Alfred Wegener Institute. He was ridiculed all his life for holding on to his sensible theory opposing the consensus of all scientific “experts”.
“…during the last interglacial period 125,000 years ago, a period when the polar surface temperature was around two degrees Celsius higher than today…”
——————————————————
WHAT???
Didn’t the worlds top scientists just tell us that 2015 was warmer than any time in the past 2 million years?
You guys need to get together and make sure your stories aren’t contradicting each other.
Be sure they will be told to do so.
“might behave in the wake of global warming. ”
What global warming?
Oh my, three to five meters in as little as a thousand years, assuming of course the interglacial doesn’t end before that. Isn’t that as fast as 3 to 5 mm per year sea level rise? Armed with this fearful prophecy I’ll be running out to buy some new waders.
Sutter’s study’s conclusion is predicated on the incorrect assumption that CO2 caused the recent warming and hence assumed the warming will continue (ignoring the observational fact the planet has not warmed for more than 18 years).
The theoretic estimated surface warming, I repeat surface warming due to a doubling of atmospheric CO2 is almost completely offset by the reduction in the lapse rate that occurs due to increased convection. Convection (hot air rises which causes cold air to fall hence changing the lapse rate) is a physical fact not a theory. The reduction in the lapse rate reduces surface warming for a doubling of atmospheric from 1.2C to less than 0.3C (by a more than a factor of four).
Hansen and his buddies ‘no feedback’ 1 dimensional CO2 forcing calculation that determined 3.7 watts/meter^2 increased warming due to a doubling of atmospheric CO2 assumed no change in the lapse rate and did the calculation for a dry atmosphere.
As the planet is 70% covered with water there is a great deal of water vapor in the atmosphere. It is a physical fact not a theory that the absorption spectrums of water and CO2 overlap so there is almost no significant increase in atmospheric warming due to an increase in CO2 from current levels if the water vapor content of the atmosphere region in question is more than 10% of saturated.
A 1986 peer reviewed paper noted the 1 dimensional feedback surface forcing for a doubling of atmospheric CO2 would be reduced by a factor of four, if the calculation was redone using a conservative back of the envelop minimum estimate of the water vapor (the calculations were purposely incorrect, as if the calculation was done correctly there is no CAGW there is no AGW CO2 problem), rather than assume ludicrously that the atmosphere is dry for the 1 dimensional calculations.
The reduction in lapse rate and the reduction in the forcing due to the fact that there is water vapor in the atmosphere and the absorption of water vapor and CO2 overlap reduces the surface warming without ‘feedbacks’ for a doubling of atmospheric CO2 by a factor of 16 to around 0.075C, less than 0.1C. As surface warming less than 0.1C is so small, the without feedbacks warming for a doubling of atmospheric CO2 is the same as the with feedbacks warming.
The general circulation models (GCM) which some refer to as 3 dimensional modeling, have a 100 parameters in them which can be subjectively adjusted. The GCMs can hence be adjusted to provide any warming or cooling that is desirable by the model.
In the pale record there is a massive increase in dust deposited on the Greenland ice sheet that coincides with the cyclic abrupt cooling events. The origin of the dust is the Mongolian desert which requires that there to be a massive increase in the speed of the jet stream, to enable the dust to be transported from the Mongolian desert to the Greenland ice sheet. Note the increase in dust on the Greenland ice sheet has happened again and again. The paleo climate researchers use the change in ice core conductivity due to the increase dust to find the abrupt climate change events.
There has been suddenly an unexplained increase in the jet stream speed (See warmists news release Yahoo for example). Of course the cult of CAGW nincompoops asserted that the increase in jet stream speed is due to global warming which is ludicrous (why did the jet stream suddenly increase now, what is the mechanism). The increase in jet stream speed is due to the solar cycle changes and is the reason (in addition to an increase in cloud cover 40 to 60 degree latitude ) why the North Atlantic ocean was in sections in the region 40 to 60 degrees latitude 10C cooling than present.
http://www.agu.org/pubs/crossref/2003/2003GL017115.shtml
http://wattsupwiththat.files.wordpress.com/2012/09/davis-and-taylor-wuwt-submission.pdf
In the 1990’s paleoclimatologists’ discovered evidence in the Greenland ice sheet core data that the periodic 200yr, 500yr, 1500yr, 8000yr, etc. climate changes (up to 20C drop in the Greenland ice sheet temperature) were rapid not gradual events. For example, the Greenland ice core data shows that the Younger Dryas cooling event occurred in a 5 year period (Younger Dryas is the name for a climate change from the current interglacial Holocene, warm period back to the Wisconsin glacial, cold period that occurred 12,800 yrs ago).
The Greenland ice core finding was not expected (the old consensus belief was that climate changes were gradual) and many at first stated the planet’s climate could not possibly change that rapidly. (The doubter’s suggested that the ice core data was flawed.) A second Greenland ice core was drilled. The second set of ice core data corroborated that the changes were very, very, rapid.
As the planet resists rather than amplifies forcing changes the massive rapid temperature changes in the paleo record require a massive forcing function. It massive forcing function is solar cycle changes. The sun can from time to time be transformed into an angry beast.
The planet is going to abruptly cool, due to the interruption to the solar cycle. The solar cycle is not slowing down, it has been interrupted. The increase jet stream speed has started. The cooling has started.
The warm blob off of the US west coast is almost gone.
http://www.ospo.noaa.gov/data/sst/anomaly/2016/anomnight.2.8.2016.gif
WA
Very interesting about the Mongolian dust layers in Greenland ice and evidence for periodic rapid cooling. I was with you entirely up till the comment about a big change needing a big forcing. The climate system is not passive but driven by powerful internal nonlinear oscillations with a fractal signature (frequent small changes, log-infrequent log-big changes).
Nonlinear oscillators can be externally periodically forced. The solar cycle and changes therefore is never strong enough to change climate by brute force. But it could easily by providing even weak periodic forcing, entrain it to regular large excursions following a solar pacing.
Quite a change in under 2 weeks…
http://www.ospo.noaa.gov/data/sst/anomaly/2016/anomnight.1.4.2016.gif
I was under the impression most if not all the Antarctic ice sheet is afloat.
Correct me if I’m wrong. This is a media phd, not science. lol
Apologies. West Antarctic ice sheet.
Your wrong. But large parts of the glacier are below sea level, so once water lifts the ice afloat, if can float away.
Most of WAIS is above sea level. There are grounded portions of Ross and Ronne ice shelves that are grounded below. Ronne is pinned by the substantial island that bifurcates it. Ross is pinned by numerous rocky seamounts. The ice can and does creep around these impediments. But muchb slower than a glacier would. The ice for both is renewed higher in the respective catchment basins. Zwally’s ice mass analysis suggests Ronne is gaining and Ross is roughly stable. WAIS ice mass loss is mainly PIG and Thwaites sea facing glaciers in the Amundsen Embayment. Details in essay Tipping Points.
Most of the ice is above, but most of the area or at least a very substantial part sits on seabed. If we believe Wikipedia.
Darn page link. Open the link in a new tab, that works.
No worries. In a thousand years we’ll all be up in the floating cloud cities if we are here at all.
“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). ”
Since climate models are almost all too warm(many are MUCH too warm)…….using incorrect assumptions about CO2, water vapor, the water cycle, clouds and so on, one has too ASSUME that they were wrong before they even started to apply their incorrect assumptions.
Saying you are assuming “a business as usual” future in a computer model and then making predictions on what will happen in 1000 years is pretty silly. First of all if the fossil fuel usage and air pollution rates in China and other developing countries continues to rise as it has for another hundred years I don’t think there will be anyone left in those countries to worry about sea levels.
If they made predictions just 500 years ago on what the year 2000 would be like assuming “a business as usual” future they would have said there would be a severe shortage of leeches available for medical “barbers”, a shortage of pigeons for communication, a shortage of mules for cargo shipping, of ink and pens for transcript copying. Imagine the rate technological advancement that we’ve had over the last 50 years continuing (or more likely increasing) for another 500 years. We have no idea what the world will be using for energy sources in 500 years.
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
What!!! and CO2 levels were much lower than today! So how did that happen?
Arrhenius wasn’t born then, silly Mike.
They used not one, but two climate models, and not one, but two simulations to “feed the ice sheet model with all the necessary climate information.” Gosh, can’t argue with that. Their thoroughness is unimpeachable. /sarc
When in doubt doom it, which also happens to correspond with reporters’ and editors’ creed.
…Fools that do not learn from the past are destined to repeat the same mistakes in the future !
So what about this continental drift ‘thingy’? How long before Antarctica wanders off and bumps into Oz or Nicaragua? Who needs a model for that? It’s obvious what will happen. Pooof! Instant defrost! The peaks of the Rocky Mountains will be a Pacific Ocean island chain. Tibet will have miles and miles of resort dotted, sandy, oceans beaches. The straits of Gibraltar will cease to be an easily defensible “choke point”. The Nile Delta will be on Somalia’s Mediterranean coast. We’re all doomed. Those rare pockets of humanity that survive will be plagued by an influx of homeless chattering, guano dropping penguins. I’m warning you! Time is running out. Act now! Write your congressman or congresswoman or congressperson or congressentity. Tell them to fully fund anti-drift research. Send your tax deductible donations to Driftpeace and save our future.
Oow! I bit my tongue. How did it end up over there in my cheek?
@ur momisugly George Grant, 12.14 pm. But it makes for a great screenplay, off to Hollywood if I were you!
As a couple of people have already mentioned, volcanic activity well below the ice may account for the West Antarctica ice melt. In East Antarctica there is virtually no ice melt. It makes sense local factors rather than global warming account for the difference.
Here is a map showing the volcanoes of Antarctica – all in the West A.
and
https://source.wustl.edu/2013/11/volcano-discovered-smoldering-under-a-kilometer-of-ice-in-west-antarctica/
Scroll down to the map showing what happens under there.
The recently discovered volcano under a km of ice isn’t shown here. Who knows how many there are.
Ho-hum! Another day, another model.
If it gets really hot in the Antarctic, maybe monkeys will emigrate to that continent. They could make friends with the penguins. Bananas could grow down there if it was hot enough, and the monkeys might eat them. Maybe the monkeys could teach the penguins to eat bananas. A descendant of Donald Trump could open some hotels and casinos down there, and they probably would feature boxing events broadcast around the world via satellite. But monkey boxers would not fight penguin boxers, on account of them being friends.
I don’t see this as a great investment opportunity because of this:
I don’t think we could even do GMO bananas down there.
…. but live polar bear/penguin action might be a good sell.
I’ve been saying that for years.
When, oh, when is some crazy entrepreneur going to take a breeding pair of polar bears and drop them off at a penguin colony in Antarctica. Obviously we would have to film the hilarious results for youtube.
Just imagine the schizophrenic reaction from environmentalists – “the carnage must be stopped – but wait – we’re supposed to love and support polar bears – but wait – the carnage must be stopped…”.
Hopefully after witnessing this, their heads would explode!!!!
IF it gets hotter ice will melt .
Give this man a PhD !
…. hold on a sec though. Another man who just got a PhD showed that CO2 causes cooling in Antarctica. What happens then ??
Take away his PhD.
“How steeply and, above all, how quickly can the sea level rise in the future? …”.
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Questions questions questions.
Will the Earth be struck by a massive asteroid?
Will there be a massive Atlantic landslide causing a Megatsunami?
Will there be a global viral pandemic?
Will Bernie become POTUS?
It seems the overall model is
man + techonology => atmospheric CO2 increase
=> atmospheric temperature increase
=> water temperature increase
=> all floating ice melts
=> all land ice slides into water and melts
=> catastrophic sea level rise
=> PHD + funding
Is there anything I’ve missed?
WOW 5mm per year and that is a doomsday prediction.
That is almost as funny as a meeting with the local council over our beach houses that are under threat from rising sea level and they wanted to stop any future development. We pointed out we wouldn’t be alive and so really didn’t care. Then they started with the crazy notion that the rate and tax payers were going to have to foot the bill. We walked them thru the process which is the same as building on an area subject to erosion for a beach house and the cost and risk is born totally by the land purchaser.
Our council saw sense and we just sign paperwork saying we know the proposed house is at risk from sea level rise and off you go and build. You have warned us what happens from here isn’t your problem. I have heard of a few councils seeking to impose draconian planning laws based on projected sea level changes and I would hope people have the sense to appeal them.