While we have record high sea ice in Antarctica, the Australian research council is figuring that a collapse of Antarctic ice is imminent, followed by 3-4 meters of sea-level rise. It’s all based on a model that they took back in time to 14,000 years ago to model “meltwater pulse 1A” seen in the graph below. The only problem is, we aren’t coming out of an ice age.
From the “Australian Research Council’s Centre of Excellence for Climate System Science”:
Current changes in the ocean around Antarctica are disturbingly close to conditions 14,000 years ago that new research shows may have led to the rapid melting of Antarctic ice and an abrupt 3-4 metre rise in global sea level.
The research published in Nature Communications found that in the past, when ocean temperatures around Antarctica became more layered – with a warm layer of water below a cold surface layer – ice sheets and glaciers melted much faster than when the cool and warm layers mixed more easily.
This defined layering of temperatures is exactly what is happening now around the Antarctic.
“The reason for the layering is that global warming in parts of Antarctica is causing land-based ice to melt, adding massive amounts of freshwater to the ocean surface,” said ARC Centre of Excellence for Climate System Science researcher Prof Matthew England an author of the paper.
“At the same time as the surface is cooling, the deeper ocean is warming, which has already accelerated the decline of glaciers on Pine Island and Totten. It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet.”
The modelling shows the last time this occurred, 14,000 years ago, the Antarctic alone contributed 3-4 metres to global sea levels in just a few centuries.
“Our model simulations provide a new mechanism that reconciles geological evidence of past global sea level rise,” said researcher UNSW ARC Future Fellow Dr Chris Fogwill.
“The results demonstrate that while Antarctic ice sheets are remote, they may play a far bigger role in driving past and importantly future sea level rise than we previously suspected.”
The accelerating melting of land ice into the sea makes the surface of the ocean around Antarctica colder, less salty and more easily frozen, leading to extensive sea ice in some areas. It is one of the reasons ascribed to the increasing trend in sea ice around Antarctica.
To get their results the researchers used sophisticated ice sheet and climate models and verified their results with independent geological observations from the oceans off Antarctica. The geological data clearly showed that when the waters around the Antarctic became more stratified, the ice sheets melted much more quickly.
“The big question is whether the ice sheet will react to these changing ocean conditions as rapidly as it did 14,000 years ago,” said lead author Dr Nick Golledge, a senior research fellow at Victoria’s Antarctic Research Centre.
“With 10 per cent of the world’s population, or 700 million people, living less than 10 metres above present sea level, an additional three metres of sea level rise from the Antarctic alone will have a profound impact on us all.”
Paper: Antarctic contribution to meltwater pulse 1A from reduced Southern Ocean overturning.
Abstract
During the last glacial termination, the upwelling strength of the southern polar limb of the Atlantic Meridional Overturning Circulation varied, changing the ventilation and stratification of the high-latitude Southern Ocean. During the same period, at least two phases of abrupt global sea-level rise—meltwater pulses—took place. Although the timing and magnitude of these events have become better constrained, a causal link between ocean stratification, the meltwater pulses and accelerated ice loss from Antarctica has not been proven. Here we simulate Antarctic ice sheet evolution over the last 25 kyr using a data-constrained ice-sheet model forced by changes in Southern Ocean temperature from an Earth system model. Results reveal several episodes of accelerated ice-sheet recession, the largest being coincident with meltwater pulse 1A. This resulted from reduced Southern Ocean overturning following Heinrich Event 1, when warmer subsurface water thermally eroded grounded marine-based ice and instigated a positive feedback that further accelerated ice-sheet retreat.
Occam’s razor I meant. Android word processing sucks.
I don’t quite understand. Are they claiming that the ice sheet floating on fresh water will melt and that this will raise the level of the ocean? Somebody had better go back and take physics again, if so, right after they withdraw the paper in abject humiliation.
If they claim that the ice sheet on the ocean will melt (triggering basically no increase in sea level because the ice is floating already) and that this will suddenly warm the nearby land and melt the kilometers-thick ice sheets on Antarctica proper from the top down, that’s a lot more complex of an assertion and I’d have to see some serious backing for it. Even if the freshwater ice melted suddenly (where all ocean ice is freshwater ice, BTW, because salt water is concentrated, melts through it, and leaves behind freshwater ice) in order for the inland waters to warm, the surface waters have to warm, and once they warm, they will cool. All they can really hope for is a sudden change in albedo or a sudden and permanent change in global atmospheric circulation patterns to be driven by the change in ice coverage, and in truth we have no idea what will happen as everything is different now relative to 14,000 years ago. Different point in the orbital cycle, different atmospheric composition, different positions of the continents and above all, different distribution of ocean and land ice everywhere. What they really should be asking is why “sudden” melts and freezes appear in the climate record at all. This is qualitatively understandable from chaos/catastrophe theory — folded hysteretic surfaces of local stability reaching a critical point and “suddenly” falling over to another sheet — but quantitatively predicting a transition to a still warmer state is pure conjecture, in particular the conjecture that there is a still warmer sheet out there to fall through to or a critical point on the sheet we are on.
Since the “sheets” of local stability in climate dynamics probably have ten or twenty important dimensions (at least), with attractor orbits in at least this number of dimensions being projected down to just a few, I very much doubt that there is much merit to this claim. It could be true, sure! Or, the growing Antarctic sea ice could be a symptom of a global cooling due to slow but stead orbital changes, or due to the changing state of the sun, or it could be pure oscillation and variation of atmospheric circulation patterns utterly beyond our control or influence. The Earth could be getting ready to cool, to warm suddenly, to remain about the same. These things are all true, all of the time. That’s the thing about chaotic systems, after all. Difficult to predict.
The worst thing about the report above is it is utterly impossible to refute, or even address. No one can prove it false, and the events it “predicts” could take place a century from now and they’d still claim — if they were alive — to have predicted it even if the causes proved to be completely different. Yes, we can imagine a series of events that would lead to sudden SLR, thank you. Yes, since we know damn-all about the actual state of the planet a century ago, we know even less about its state 14,000 years ago and what we don’t know has error bars large enough for you to be able to claim that some variables are similar now to then, even though the actual state of the globe is vastly, overwhelmingly different.
Meh!
rgb
I chased up the link and , unusually for a paywalled paper, it gives a list of the cited refs , 2 of which were free access. One of them was the BEDMAP2 summary of ground icesheet thickness and underlying bed topography which is of interest in its own right , but not obviously relevant to what I had been looking for – the geological data that they claim underpins their model of warm water underbelly melting 14000 yrs BP .
There is a lot of information on that meltwater event and to the role of insolation and post glacial degassing of CO2 but you need academic credentials to get further than the abstracts.
I simply could not ascertain what geological data they could find for an event that occurred 14000 yrs ago in an open ocean involving ice on water.
I’m sure everyone when going through grade school remembers the science experiment where the teacher put an ice cube in a cup, and then filled the cup to the brim. The teacher would ask the students what would happen when the ice melted. Would the cup overflow? Sea ice melt does not cause sea levels to rise; melting land ice does.
“With 10 per cent of the world’s population, or 700 million people, living less than 10 metres above present sea level, an additional three metres of sea level rise from the Antarctic alone will have a profound impact on us all.”
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“Metres” ??? Is this how they spell meters? Anyhow, the problem I have with such bombastic claims (i.e. “imminent”, “disturbingly close”, “3-4 meters”, “profound impact”, …), as well as their coverage by the MSM, is that they are only intended to cast doom and gloom onto uninformed public. Most laymen reading this get a first (and lasting) impression that it will be like some giant tsunami that will wash them away while asleep in the middle of the night. The fact that such changes in ocean levels happen over long periods of time on the human’s time scale (100’s or 1000’s of years) is usually obscured somewhere deep in the article, if anywhere.
The fact that these “changes” of SL rise are not happening period,, will likely not be conveyed.
I see a hockey stick in that graph. Anyone else see it? You have to lie on your side, then look at it using a mirror. But it’s there. We’re doomed.
Fine. Nice tale. I’ve heard it before, but strangely, not one person has ever showed measurements even hinting it is true.
So, show me the measurements:
Antarctic sea ice area = 100% coverage = 16.6 million sq kilometers a few days ago.
15% ice coverage = 20.0 million sq kiloeters.
Antarctic sea ice area has been steadily increasing every season of the year, every year since 1992.
Antarctic sea ice has been increasing rapidly since 2011 at a rate of 500,000 sq kilometers per year.
Antarctica has enjoyed a frightening sea ice anomaly as large as 2.0 million sq kilometers back in June, has had an anomaly the past weeks of 1.4 to 1.6 million sq kilometers.
What WAS the previous salt water salinity for the region every year since 1992?
What is the salinity now? For the entire 20,000,000 kilometers?
How deep is this supposed fresh water run off diluting the seawater? 10 meters? 50 meters? 100 meters? 1 meter?
How many trillion tons of seawater was required to dilute the seawater so far so WHAT temperature of air is now freezing more seawater faster? Again, show me the measurements.
The actual measured average air temperature for Antarctica has been decreasing since 1992 … WHAT CAUSED THE LAND-ICE TO MELT when are temperatures are actually measured across the continent as going down?
How much fresh water is required to “dilute” 20 million sq kilometers of sea ice?
Oh! Right. Land winds have been blowing the Antarctic sea ice away from the continent, so more sea ice forms near the continent mass, so the edges keep extending.
Try another one: Actual Antarctic winds do NOT always blow that direction (away from the pole, only certain area. Sea winds around the continent swirl and eddy in large circles. And, there are NO measurements establishing the claim either: Merely your hype and exaggerations based on a “assumed knowledge” that the “global air above Antarctica is “hotter” … But it is NOT hotter. The whole premise is false.
There is a myth that sea ice does not contain salt.
It does. Here is an x-ray micro-tomograph (29 micron pixel) of sea ice:
http://i1374.photobucket.com/albums/ag415/ozymandius2/sea_ice_rtd_0320_zpse00cb3e7.png
The white lines are salt trapped inside the ice (the dark spaces are air bubbles).
So when sea ice melts it does not change local salinity by much.
Actually it does, the salt is progressively forced out of the ice, the older the ice the lower the salinity. Multiyear ice can be melted for drinking water.
http://nsidc.org/cryosphere/seaice/characteristics/brine_salinity.html
Thanks, good to know. How much Antarctic sea ice is multi-year?
More to the point, how much of the expanding new Antarctic sea ice is multi-year?
I have the impression its quite a small fraction – maybe I’m wrong.
Easy to calculate:
Antarctic Sea ice area at minimum (in mid-February) has been increasing for many years: It has been 2.5 Million sq km’s the past 2 years. So, a few days ago during the all-time record high Antarctic sea ice of 16.6 mMkm^2 means no more than 15% of the Antarctic sea ice could be multi-year.
Earlier, when the planet was colder and the Antarctic sea ice was measured oscillating between a low of 1.75 Mkm^2 and a maximum of only 15.5 Mkm^2, at most, only 11.3 % of Antarctic sea ice could be multi-year ice.
Published references use a 10% value for multi-year Antarctic sea ice.
Notice the difference between Arctic and Antarctic multi-year sea ice: The Arctic multi-year ice is piled up by the wind against the northern Canadian coast and between the Canadian coastal islands. 3, 4, and even 5 year ice is commonly measured. The Antarctic multi-year ice is isolated in little coves and bays all around the continent where it was pushed by the prevailing winds BACK TOWARDS the coastal rocks!
This behavior is exactly opposite what the “consensus excuse” when it claims offshore winds blow the sea ice away from shore and cause more sea ice to form. Also, the steady increase since 1992 in Antarctic sea ice anomaloy occurs across all seasons and all years. If land-ice meltwater were causing the Antarctic sea ice anomaly by diluting the oceans around the Antarctic continent, then Antarctic sea ice anomaly would differ (slow) as the distance between the Antarctic sea ice edge and the coastal glaciers changed during the year. It has NOT changed.
(Anarctic glaciers) “…may play a far bigger role in driving past and importantly future sea level rise than we previously suspected.”
Give me a break! Along with Greenland, what other sources did you previously suspect? The CAGW cliched language used by all the Team is a measure of the absence of thought in these papers.
““The big question is whether the ice sheet will react to these changing ocean conditions as rapidly as it did 14,000 years ago,” said lead author Dr Nick Golledge …”
Dr. Nick, this is not the big question! A bigger one is, “how the heck do you know that it reacted at all to these highly contentious conditions 14,000 years ago. You are completely out of phase with the cycle. We are closer to going into a new glacial max than just coming out of one!!! Geology hand waving 101 taught at your self-styled ‘Centre of Excellence’ notwithstanding. You Aussie clime stalkers are showing the hysterical signs of imminent Fundalectomies. Chris Turney, who terminated his own career when, as a swashbuckler on the Ship of Fools, he was looking for signs of global warming in Antarctica and needed to be rescued from freezing in for the winter, is now impotently raising alarm that, with the effect of global warming, the Antarctic Ice is going to dump the emperor penguins onto the shores of Tasmania and NZ or some such…I didn’t bother to read that paper, although I was able to surmise it because it was going to be worse than “previously expected”.
Here is a bulletin for you guys. You know the game is up and I feel for your desperation, but odds are you guys are going to be getting a lot of cooling weather from Antarctica not “previously expected”. If you push the global warming causation too far, then you emasculate it. It can be ascribed to the glacial maxima, the interglacials and everything in between, then where are you? That’s even a bigger question.
Now the antartic ice loss is affecting gravity itself!
http://www.sciencealert.com.au/news/20140210-26272.html
Dirk Pitt: While I agree with everyone here that these tossers at the UNSW and the Centre of Excellence-yadda-yadda are a little off this planet (what colour is the sky in their world?), you display mental insularity as well. The measurement unit in the metric system (SI) is described as “metre”, in French; and the French developed the first stage of the SI.
“Meter” is an American version. Other countries use other terms based on their own languages. When Australia adopted the SI back in the early 1970s, we also decided to use, in the main, these French spellings.
Your comment is a perfect example of insularity.
Back in your box …
“The research published in Nature Communications found that in the past, when ocean temperatures around Antarctica became more layered – with a warm layer of water below a cold surface layer – ice sheets and glaciers melted much faster than when the cool and warm layers mixed more easily.”
They reversed cause and effect. The layering of water is the effect. Melting of ice sheets and glaciers is the cause. Cold surface layer will not melt more ice. More ice water will cool the surface layer.
“The big question is whether the ice sheet will react to these changing ocean conditions as rapidly as it did 14,000 years ago,” said lead author Dr Nick Golledge, a senior research fellow at Victoria’s Antarctic Research Centre.
No because the glacial period is over 11,700 years ago. The ice sheets are gone except in Antarctica and Greenland. Have seen lately the kilometer-thick ice sheet in New York?
I particularly like the scare stories the warmists like to spin with sea level change. I wonder how many of them lie awake at night lamenting on the foot or so of sea level rise that resulted in displaced people and land loss over the last 150 years or so. The horror.
“I wonder how many of them lie awake at night lamenting “
Well, well:
http://notrickszone.com/2013/10/31/green-psychologists-confirm-climate-alarmists-are-making-themselves-mentally-sick-doomer-depression/
“It turns out the alarmists, with all their climate doom and gloom, have only succeeded in spreading depression among themsleves and those around them.”
Corroborated proof is the last thing they want. Thank you very much, now here’s your redundant cheque.