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.
Actually the main fault with this scenario is that it requires that the MWP-1A was to large extent due to a collapse of the Antarctic Ice-cap rather than the Laurentide and/or Eurasian ice-caps. The big problem with this is that MWP-1A was so big 14-20 meters of sea-level in just 500 years, while the total Antarctic contribution to sea-level rise since the glacial maximum 18,000 years ago to the present day is only about 20 meters.
So however you turn and twist, most of that meltwater was from the northern hemisphere. Some of it was certainly from Antarctica, because the sea-level rise would by itself have caused the edge of the Antarctic ice to retreat. The Antarctic ice at that time was at the edge of the continental shelf almost everywhere, and such an ice-edge isn’t stable when water depth is >500 meters, so any sea-level rise will cause increased calving and ice-edge retreat. No need for fancy “layering” of sea water, or anything else, simple knowledge about the mechanical strength of glacial ice is enough. However this simple explanation is politically useless since there is no large amount of Northern-hemisphere ice available to destabilize ice edges in Antarctica today (Greenland is small fry, and has an inherently stable icecap). Hence the need for a more complicated mechanism that can be catastrophically modelled.
The climate scientists used Meltwater Pulse 1A as their assumption.
How did they not have the basic understanding of the event that tty outlined here?
Do they sit in a room and ask themselves just how much fantasy can we make up and get away with it? They must have done exactly that.
Hence the need for sophistication in said model.
Climate models are confirmed not to reflect reality. They do not show “the pause” for instance.
I think that the main reason for that is that the “sophisticated” climate models are not even able to reflect the simple lapse rate in the atmosphere – and therefore miss the energy budget of the atmosphere.
So what is being done is to use simple weather models to model climate. Climate is about long term energy balance, not local weather the next 2-3 days, so they use innapropriate models on the principle… ahmmm what principle?
Tell me somebody I am wrong and these “scientists” do not make such “mistakes”?
So these models which fail the energy budget of the atmosphere are used for further studies in conjunction with other models?
I’m still trying to get this story straight. Global warming concentrates warm air over the Antarctic land, so the ice melts. So the air is warmer than 0C. The resulting water pours into the sea, where it sits on top of a layer of heavier, warmer, salt water. The warmer water doesn’t warm up the fresh water. And the warm air stops at the shoreline. Antarctica Is surrounded by air cold enough to freeze the fresh water. But this cold air does not spread inland under the warm air.
Is that what is supposed to be happening?
What’s happening is sea ice extent has grown in line with it getting colder.
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“Study Finds Antarctic Sea Ice Increases When It Gets Colder”
August 17, 2013
http://notalotofpeopleknowthat.wordpress.com/2013/08/17/study-finds-antarctic-sea-ice-increases-when-it-gets-colder/
Another thing these modellers forgot to tell you is this. Extreme snowfalls observed will offset some of their
hypothesizedmodeled collapse. I vaguely recall that the IPCC has projected enhanced snowfalls over Antarctica. I maybe wrong, will try and check.Here it is.
Jimbo;
reread the article we are discussing here, the Antarctic is warming, it says so right in the article it has to be true stop with the evidence crap!
sophisticated ice sheet and climate models and verified , sophisticated or not gigo is still gigo especial when there is motivation to get the ‘right results . But sooner or later it was clear they would have to come up with ‘some-way’ that a growing Antarctic is a problem rather they pretend it was not an actually reality.
I’ll bet this is another peer reviewed article so i must make sense!
How do people like these sleep a night when they know that they are spreading falsehoods and alarmism?
Then add in the press as this is how they get the public’s attention/circulation. They will no doubt represent the 500 years as “could happen tomorrow”.
Lets see what the seals say-
http://news.agu.org/press-release/elephant-seals-help-uncover-slower-than-expected-antarctic-melting/
“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.”
So they are using a model based on a model. Yep, it’s models all the way down.
Kind of like zero + zero = zero. And yet they really believe the more zeroes added together the more significant the result.
When did the primary function of science become administrative and bureaucratic as in clueless?
so how again are they able to measure water layers from 14,000 years ago ? I’m calling BS …
“The reason for the layering is that global warming in parts of Antarctica …”. Really, global warming in only parts of Antarctica? Does anyone ever read these papers before publishing to eliminate idiotic statements like this? When I was an auditor, if I had written something this stupid that made it into an issued audit report, I’d have been roasted alive by my superiors.
I don’t know, but it would seem to me that the increase in sea ice would increase the amount of cold water at the surface, which would then sink, causing more mixing and an increase in the ocean current circulation. I think what we are going to see is a massive La Nina period when all that cold water starts welling up in the central pacific, causing global temps to cool even more.
But like I said, I’m just guessing.
No mention of increased albedo.
No no noooooo!
The cold water CAN’T sink. It’s being held in place by the WARM water below it!
I thought the cold water was fresh and therefore less dense than the warm salt water under it. No one has told me why the warm water doesn’t warm up the cold water, but I’m guessing some major sorcery is involved.
That pulse, 14k years ago, did it correspond to the melting of the Laurentide Ice Sheet?
We know it was there, and now it isnt, that ice must have caused a big rise in sea levels when it melted. Could the melting of this ice sheet explain the data here?
If so, it suggests that the ice sheet melted very rapidly? Why would that happen so quickly?
Were there any other ice sheets of this thickness so far south at the time just before the melt?
Shouldn’t they be renamed the “Australian Research System Excellence and Wisdom In Theorising Science” (sarc tag not necessary, surely).
To accomodate US spellings/usages, they would need the alternate “Australian Science System Wisdom In Theorising Service”.
Just saying…
To get their results the researchers used sophisticated ice sheet and climate models = Magic Eight Ball autographed by Jean Dixon
“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.”
I see. So “parts of Antarctica” is pretty vague. If he means Western Antarctica then he has some splainin to do to get that fresh water thousands of kms away to the other side of the continent without it mixing. I expect the models can manage it, though.
And that is the problem. They will admit anything except give into the cold.
“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.”
One more thing. If the ice really is melting at a fantastic rate underwater and melting Antarctica from below then are we measuring that? Is the ice sheet retreating underwater?
Sophisticated ice sheet and climate models mean they used 20 lines of code instead of 10. 🙂
Chevy, “But, Emily, the temperature isn’t going up.”
Gilda, “Oh, never mind.”
I’m surprised the report didn’t include an estimate of the proportion of the world’s population which lived within 10 metres of sea level 14000 years ago. Imagine the social upheval which would have resulted in having to move back so unexpectedly.
Yeah, Noah’s flood perhaps?
GJiven the time-frame of 14,000 years ago, the paper is talking about the Bolling Oscilation, wherein it is estimated that the global temperature rose by 12 C in about a century – how is that for unprecedented warming? First let them explain how this happened without much less CO2 in the atmosphere than there is at present. Well, the Melankovitch cycles can explain it. But did they mention what happened after the Bolling Oscilation? Nope, but what did happen, and rather quickly, was a massive cooling that made the “ice age” return for another few thousand years.
Only one thing is certain from this paper, these are times of desparation and despair in Australian climate science. Their grant funding is far more likely to collapse before any Antarctic glacier does.
It t’was 2 or 3 years ago or so that I conjoined these two (2) proxy graphs so that I could better see the relationship between the two.
Thus, please note on the following that Meltwater Pulse 1A occurred almost 4,000 years prior to the Holocene Climate Optimum, ….. and thus it is my opinion that surface temperatures had to have been extremely “warm” during that 700+- years period for enough glacial ice to melt resulting in a 30 meter increase in sea level.
Maybe a lot “warmer” than during the height of the Climate Optimum simply because of the “melting properties” of large volumes of solid ice.
Post Glacial Sea Level Rise and Holocene Temperature Variations
http://i1019.photobucket.com/albums/af315/SamC_40/HoloceneInterglacialmeltwatertemperatureMediumWebview.jpg
It’s worse than that…
https://www.facebook.com/topic/Antarctica/104098646292810?source=whfrt&position=3&trqid=6065626731714258710
I cannot find any other source.
I ‘m getting sick and tired of the garbage being produced by this group.. As my mentor used to say “they wouldn’t know the difference between sh*t and clay”.
More ice because of warming fails the Occam’s [razor] test
But it passes the politically correct total bollocks test.
Please show us the evidence for deep water cooling (again conveniently where measurement is hardest) and decreased salinity.
Decreased salinity can also be due to accelerated cold water formation and downwelling which pulls down the salt, BTW.