From the POTSDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH (PIK)
The warmer the higher: Sea-level rise from Filchner-Ronne ice in Antarctica
The more ice is melted of the Antarctic Filchner-Ronne shelf, the more ice flows into the ocean and the more the region contributes to global sea-level rise. While this might seem obvious, it is no matter of course for the huge ice masses of Antarctica: parts of the ice continent are characterized by instabilities that, once triggered, can lead to persistent ice discharge into the ocean even without a further increase of warming – resulting in unstoppable long-term sea-level rise. In the Filchner-Ronne region however, ice-loss will likely not show such behavior, scientists from the Potsdam Institute for Climate Impact Research now found. Published in Nature Climate Change, their study shows that in this area the ice flow into the ocean increases just constantly with the heat provided by the ocean over time.
“While for other parts of Antarctica unstoppable long-term ice loss might be provoked by a single warming pulse, caused by nature itself or human action, ice loss in the Filchner-Ronne region increases directly with ocean warming,” lead author Matthias Mengel explains. “This is good news, because it is in our hands to determine how much the region contributes to the global sea-level rise.” Ocean warming results from greenhouse gases in the atmosphere, produced by humankind’s unabated burning of coal, oil and gas. Importantly, however, the oceans might not respond linearly to atmospheric warming, and not in the same way in all parts of the world. This includes the risk that ocean temperatures first lag behind, and then rise rapidly.
“Good news” yet only compared to other parts of the ice continent
The Filchner-Ronne shelf covers an area bigger than Germany; its grounded-ice tributaries store water equivalent to a total of several meters of sea-level rise. “Our calculations show that this relatively small part of the Antarctic ice sheet within just 200 years of unabated climate change could contribute up to 40 centimeters to global sea-level rise,” says Mengel. “This kind of sea-level rise alone could already be enough to bring coastal cities like Hamburg into serious difficulties.”
“At present, most Antarctic ice shelves are surrounded by cold water masses near the freezing point,” co-author Anders Levermann says. “The topography around the ice continent acts as a barrier for heat and salt exchange with the northern warmer and saltier water masses, creating a cold water wall around the continent.” Projections of the breakdown of this front in ocean simulations for the Filchner-Ronne region under atmospheric warming raised concerns that such ocean instability might lead to unstoppable future ice loss also from this part of Antarctica, as is projected to occur in the Wilkes Basin region, for instance. “We found that this is not the case for the Filchner-Ronne shelf – which luckily means that we can still very well limit the ice loss in this area by limiting greenhouse gas emissions.”
Different mechanisms in different regions
Sea-level rise poses a challenge to coastal regions worldwide. While today sea-level rise is mainly caused by thermal expansion of the warming oceans, and by the melting of mountain glaciers, the major contributors to long-term future sea-level rise are expected to be Greenland and Antarctica with their vast ice sheets. The causes of ice loss differ greatly between the two. While on Greenland ice melting at the surface plays a large role, the Antarctic ice sheet loses almost all its ice through ice flow into the ocean. The simulation of the Antarctic ice flow is complex because the flow can become unstable. Ice shelves, the floating extensions of the ice sheet, can act as a break to the ice flow and inhibit instability. Warming oceans around Antarctica that melt the ice shelves therefore increase the risk of high sea-level rise.
The Parallel Ice Sheet Model, as used by the authors, resolves unstable grounding line retreat and simulates the flow of both the ice sheet and the ice shelves. It can therefore help to answer urgent questions as to the extent of Antarctica’s sea-level risks.
“It is more difficult to determine the risk that comes with global warming in parts of Antarctica that are considered unstable, and less difficult for the Filchner-Ronne region that responds linearly to global warming,” concludes Levermann. “One thing is clear: the more warming we cause by burning coal, gas and oil, the more expensive it will be for coastal regions to adapt.”
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Article: Mengel, M., Feldmann, J., Levermann, A. (2015): Linear sea-level response of Antarctic tributaries to strong projected ocean warming underneath the Filchner-Ronne ice shelf.Nature Climate Change (Advance Online Publication) [DOI: 10.1038/nclimate2808]
Link to the article once it is published: http://dx.doi.org/10.1038/nclimate2808
Link to a previous study on the Wilkes Bassin ice plug: https://www.pik-potsdam.de/news/press-releases/archive/2014/uncorking-east-antarctica-yields-unstoppable-sea-level-rise?set_language=en
The following paper explains why there will not be a runaway break up on the Antarctic and the Greenland icesheets.
http://www.principia-scientific.org/why-the-greenland-and-antarctic-ice-sheets-are-not-collapsing.html?utm_campaign=aug-20-2015&utm_medium=email&utm_source=newsletter
Not sure with where to post this, But I support this guy:
Excellent.
At this point in time, anyone who repeatedly cites “the 97% of scientists support global warming” talking point is either too completely ignorant of the facts to be given a voice in public affairs, or is a blatantly lying propagandist.
LOL! Slogans versus Fact. Shot down in flames.
So that subglacial ash sheet the size of Wales near PIG was the imagining of the British Antarctic Survey? Whole place has the look of a cordillera to me…But, no, it’s your SUV or your plane ride causing all the melting.
I remember fondly the days when you could discuss vulcanism outside the context of explaining away the LIA or any other inconvenient coolings.
“Importantly, however, the oceans might not respond linearly to atmospheric warming, and not in the same way in all parts of the world. This includes the risk that ocean temperatures first lag behind, and then rise rapidly”
Presumably the “lag behind” refers to ocean temperature increases lagging behind atmospheric temperature increases….if and when the atmosphere is warming.
The surfaces of the world’s oceans are in constant intimate contact, constantly mixed with the atmosphere. How could an increase in atmospheric temperature not be almost immediately transferred to the oceans ?
Why would the oceans decide not to warm up immediately, then decide they’d lingered bit and better catch up? And what would the difference be between water in the North Pacific and the South Atlantic that it would decide to warm differently [and presumably cool differently if that became necessary]?
“Why would the oceans decide not to warm up immediately, then decide they’d lingered bit and better catch up?”.
This has to do with the vast heat capacity of the oceans. The oceans have a heat capacity that is 1000 times greater than the atmosphere. According to the blog WUWT here:
http://wattsupwiththat.com/2011/04/06/energy-content-the-heat-is-on-atmosphere-vs-ocean/
What that also means is that if you were able to experimentally warm the atmosphere by 1 degree over, let’s say, ten days, and hold it at that temperature (Using all the world’s nuclear weapons, perhaps). Then the additional heat (energy) that was transferred to the ocean during that period would not raise the average temperature of the oceans significantly. Not even measurably in the long run.
I’m not sure what the rate of flow of heat from the atmosphere into the oceans is. If I get the time then I will look up this topic, out of curiosity.
BUT, the point that I am making is that the heat capacity is so big that changes are inevitably going to take a long time. i.e. a sudden change in atmospheric temps will take a long time to be matched by an equivalent adjustment in the ocean temperature. That much should be intuitively obvious.
But, I may find time soon to look up the estimated heat transfer rate.
(For simplicity and clarity I have ignored consideration the additional complexity, that the oceans also transfer heat with the ocean bottom on which they sit. And, I have also ignored the effects of fish farting!!)
Just reading P I K is enough to trigger switchoff before you even get to M O D E L.
These guys seem to live in a universe where thermal processes are always governed by positive feedbacks and instability. Everything is always on the verge of tipping, runaway or in this article “uncorking”.
Thermal changes in the atmosphere are going to “snowball” into bigger changes. (ironically)
To paraphrase Farage’s abuse of the EU bureaucrats, “just what planet are they on?”
What is interesting to consider about all the thermal events experienced in life and engineering, is that they are all dominated by negative feedbacks. Mostly annoyingly so.
And so, whether you are trying to heat your home in winter or trying bring water to the temperature at which you can make a cup of tea, you have to keep hurling energy into the process. And as soon as you stop hurling energy in, the process reverts.
At no point has anyone found a way to make these processes “tip” or “runaway” or “snowball” or “uncork”, so that you can have free central heating or free cups of tea.
I got stung at the end of the nineties when I watched some BBC propaganda that told me about runaway warming from methane releases, ice albedo changes, water vapour etc.
Part of me must have been attracted to believing in an oncoming apocalypse (diminshment of personal responsibility perhaps), because my experiences of everything else, so far, in my life had shown me that thermal systems are not unstable in this manner.
Later, of course, I discovered that I had simply been bullshitted and all that I was told was motivated speculation.
But isn’t it interesting that the entire debate revolves around this conception of stability/instability and negative/positive feedbacks?
So, I now tend to see the modern climate as some marbles in a wok. If you tilt the wok then the marbles move, a little.
But, the whole of the alarmist community seems to prefer to see the climate as marbles ON a wok.
And they are always in danger of completely losing their marbles.
Clarification, I meant ON a wok, that is upside down, of course!! An upturned wok world.
How could sea level rise or fall be anything other than “unstoppable”?
Well, it could also be “unprecedented” or “significant” *grin*
“…says Mengel. “This kind of sea-level rise alone could already be enough to bring coastal cities like Hamburg into serious difficulties.””
I couldn’t find any reason on line why Hamburg was particularly ‘threatened’. Nothing on the docks looks like it was built more than 200 years ago. The sea level rise is not accelerating, it is tapering off. In 200 years time Hamburg will be mostly rebuilt except maybe the Cathedral of St Michael’s which is beautiful and not near the water.
The sea level in Hamburg was 140 metres higher a few millions years ago. I supposed they have to move their tusk huts back from the beach.
IPCC 1990: “No convincing evidence that sea level rise accelerated in the 20th century” – See more at: http://notrickszone.com/2014/01/23/german-review-sea-level-rise-way-below-projections-no-hard-basis-for-claims-of-accelerating-rise/#sthash.2fE87O1y.dpuf
!!Mythos trigger Warning!!
Best it stay cold, lest the dreaded Shoggoths awaken.Just sayin’
A public service announcement from the Office of Elder Thing Affairs Antarctica.
You may return now to your consensus Reality Safe Spaces.
The Antartic did not glaciate until 34 million years ago. At that time, CO2 levels were about 900ppm. According to the bullshit Greenhouse Effect theory this should never have happened. Why did an ice cap form there? The answer is in the continental drift of Africa, South America and Australia northwards as Antartica moved over the pole. As those continents moved north, the Deep Ocean Conveyor was now able to move cold water along the entire coastline of the southern continent, initiating a glaciation….even while there was still no Artic Ice Cap, which did not form until 3 million years ago, when the North and South Americas met and cut off the Panama Current.
400,000 years after the loss of the Panama Current and the glaciation of the Artic, the Quaternary Ice Age began. This can also be explained by the shift in ocean currents according to the new alignment of the land masses. The fresher water flowing in the Artic Ocean through the Bering Sea, which was much larger then, froze. As the ice accumulated, it reflected more sunlight into space, cooling the planet even more. When enough ice accumulates, the Bering Sea is drained by lowering sea levels and cuts off the flow of fresh water into the Artic.
As Greenland and Europe moved farther from each other, a current was created that is now the AMOC. Here, warm salty water was moved into the Artic from the tropics which melted the ice and made the sea levels rise. This in turn flooded the Bering Sea and as the Greenland ice melts, it changes the salinity of the AMOC until fresh water dominates agains and the AMOC system shuts down, stopping the warm water from going so far north and allowing the fresh water to freeze again.
This happens in cycles. Originally about 45,000 years between cooling and warming, now about 100,000 years of cooling followed by a short 15-20,000 years of warm, which we are in now. This change in periodicity can be adequately explained by the constant narrowing of the Bering Sea and the growing gap between Greenland and Europe. Eventually the flow of fresh water will be cut off and the AMOC will be continuous, triggering the end of the current Ice Age.
So this is why the world is warming. That massive Artic ice cap has melted, reducing albedo and reflecting very little sunlight back into space. Once the currents change, as they have without fail for the last 2.6 million years, the ice will return, the albedo will increase, and it will get cold again. This will happen soon, probably within the next one or two thousand years.
It has nothing to do with CO2 levels or man. This is a massive planetary process involving continental drift and ocean currents that’s been going on since man first started learning to bang rocks together to make crude tools. No legislation, government pronoucements or non-profits groups demanding we all stop eating meat and drive electric cars is going to stop it. Only a fool thinks they can tell a planet what to do.