Antarctica could raise sea level faster than previously thought

Aug 14, 2014
Image: National Science Foundation

Ice discharge from Antarctica could contribute up to 37 centimeters to the global sea level rise within this century, a new study shows. For the first time, an international team of scientists provide a comprehensive estimate on the full range of Antarctica's potential contribution to global sea level rise based on physical computer simulations. Led by the Potsdam Institute for Climate Impact Research, the study combines a whole set of state-of-the-art climate models and observational data with various ice models.

The results reproduce Antarctica's recent contribution to sea level rise as observed by satellites in the last two decades and show that the ice continent could become the largest contributor to sea level rise much sooner than previously thought.

"If greenhouse gases continue to rise as before, ice discharge from Antarctica could raise the global ocean by an additional 1 to 37 centimeters in this century already," says lead author Anders Levermann. "Now this is a big range – which is exactly why we call it a risk: Science needs to be clear about the uncertainty, so that decision makers at the coast and in coastal megacities like Shanghai or New York can consider the potential implications in their planning processes," says Levermann.

Antarctica Currently Contributes Less Than 10 Percent to Global Sea Level Rise

The scientists analyzed how rising global mean temperatures resulted in a warming of the ocean around Antarctica, thus influencing the melting of the Antarctic ice shelves. While Antarctica currently contributes less than 10 percent to rise and is a minor contributor compared to the thermal expansion of the warming oceans and melting mountain glaciers, it is Greenland and especially the Antarctic ice sheets with their huge volume of ice that are expected to be the major contributors to future long-term sea level rise. The marine ice sheets in West Antarctica alone have the potential to elevate sea level by several meters - over several centuries.

According to the study, the computed projections for this century's sea level contribution are significantly higher than the latest IPCC projections on the upper end. Even in a scenario of strict climate policies limiting global warming in line with the 2°C target, the contribution of Antarctica to global covers a range of 0 to 23 centimeters.

A Critical Input to Future Projections

"Rising sea level is widely regarded as a current and ongoing result of climate change that directly affects hundreds of millions of coastal dwellers around the world and indirectly affects billions more that share its financial costs," says co-author Robert Bindschadler from the NASA Goddard Space Flight Center. "This paper is a critical input to projections of possible future contributions of diminishing ice sheets to sea level by a rigorous consideration of uncertainty of not only the results of models themselves but also the climate and ocean forcing driving the ice sheet models. Billions of Dollars, Euros, Yuan etc. are at stake and wise and cost-effective decision makers require this type of useful information from the scientific experts."

While the study signifies an important step towards a better understanding of Antarctica in a changing climate and its influence on within the 21st century, major modeling challenges still remain: Datasets of Antarctic bedrock topography, for instance, are still inadequate and some physical processes of interaction between ice and ocean cannot be sufficiently simulated yet.

Notably, the study's results are limited to this century only, while all 19 of the used comprehensive climate models indicate that the impacts of atmospheric warming on Antarctic ice shelf cavities will hit with a time delay of several decades. "Earlier research indicated that Antarctica would become important in the long term," says Levermann. "But pulling together all the evidence it seems that Antarctica could become the dominant cause of rise much sooner."

Explore further: Uncorking East Antarctica yields unstoppable sea-level rise

More information: Levermann, A., Winkelmann, R., Nowicki, S., Fastook, J.L., Frieler, K., Greve, R., Hellmer, H.H., Martin, M.A., Meinshausen, M., Mengel, M., Payne, A.J., Pollard, D., Sato, T., Timmermann, R., Wang, W.L., Bindschadler, R.A. (2014): Projecting Antarctic ice discharge using response functions from SeaRISE ice-sheet models. Earth System Dynamics, 5, 271-293. DOI: 10.5194/esd-5-271-2014

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User comments : 19

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antigoracle
1.5 / 5 (16) Aug 14, 2014
Oh, imagine the desperation of the AGW Cult to propagate this lie. The ocean is warm enough to melt the ice shelves but not the growing sea ice.
runrig
4.5 / 5 (17) Aug 14, 2014
Oh, imagine the desperation of the AGW Cult to propagate this lie. The ocean is warm enough to melt the ice shelves but not the growing sea ice.


Another swot required I see for an Anti spam post. Just the usual folks .... nothing to see, so move along please.

No, instrument/satellite data show the ocean around Antarctica warming and also sea-ice pushing out further from the coast.
Now folks - would you expect warmer water and air temps (on ave) to make more ice?
Precisely - that's why it doesn't.
So what is it that could do that........... err. Now let's see the ice is blown! - really, well I never would ave credited it.
Data shows winds to have increased and this being so they will be less convergent into the continent (on ave).
Now then ... this is what is needed to be intelligent in understanding science. The need to think in more than one dimension.

As I said, move along folks - just a regular denial of the spamming bollocks emanating from mr Anti's keyboard.
FFS
antigoracle
1.3 / 5 (14) Aug 14, 2014
Yep, man made CO2 is warming the ocean closest to the continent, where it's melting the ice shelves, and not further out where the much thinner sea ice proliferate. That's the AGW Cult's "science".
runrig
4.7 / 5 (14) Aug 14, 2014
Yep, man made CO2 is warming the ocean closest to the continent, where it's melting the ice shelves, and not further out where the much thinner sea ice proliferate. That's the AGW Cult's "science".

No the melt is generally in the summer and the ice spread in winter. And of course the limitation of the sea-ice is the point at which melt overtakes advection.
Thanks Anti ... and I'm waiting for the explanation of how (in your interpretation) sea-ice can proliferate if both sea and air temps are higher (on ave) than historically.
Are you saying it's because sea and air are in fact colder.
OK - lets go around the bowl again and I'll ask you to give me evidence of that.
If you cannot - can you please shut the f***k up
Ta muchly.
aksdad
1.4 / 5 (11) Aug 15, 2014
Computer simulations of unpredictable climate processes or measurements of what's actually happening: which do you believe?

Global sea level rise is currently measured as 2.8 ± 0.8 mm/yr (tide gauges) to 3.2 ± 0.4 mm/yr (satellite altimetry). That rate hasn't changed significantly in the last 20 years. See here:

http://sealevel.colorado.edu/

At 3.2 mm/yr that works out to 32 centimeters a century, about 12.6 inches. The simulations suggest an "additional 1 to 37 centimeters in this century already".

First of all, really? They're making a prediction that Antarctic glacier melt could contribute essentially nothing all the way up to 37 centimeters in addition to current sea level rise? How many bookies guarantee you money if your horse comes in anywhere from 1st to 37th place? Silly. That's not a prediction; it's a blind guess.

Secondly, where's the evidence that sea level rise is accelerating according to their predictions? There is none. See for yourself.
aksdad
1.4 / 5 (11) Aug 15, 2014
By the way, runrig, regardless of the theories of why it's happening, Antarctic sea ice is observed to be growing every year.

https://nsidc.org...e_index/ (click on "Antarctic")

And not all of the Antarctic ocean is warming; some is cooling. It's ironic that the favorite theory of alarmists is winds blowing sea ice around; a theory they reject about why the Arctic (North Pole) sea ice has been diminishing in the last 30 years. For example, see:

http://www.skepti...iate.htm

To skeptics, it makes sense that winds and ocean currents would have a greater effect on sea ice in both places than any postulated warming from "greenhouse gas" emissions. Historic records of ice packs in both places over the last century demonstrate the large natural variability of ice pack extent.

Anyway, sea ice has no bearing on the discussion of Antarctic glacier melt; they're different things.
antigoracle
1.8 / 5 (10) Aug 15, 2014
I'm waiting for the explanation of how (in your interpretation) sea-ice can proliferate if both sea and air temps are higher (on ave) than historically.

Very good question runrig. I know sea ice is proliferating because -
http://earthobser...id=82160

It's your cult that claims the globe is cooling because all the heat is suddenly going into the oceans, so I would toss your question right back at you.
runrig
4.4 / 5 (7) Aug 15, 2014
I'm waiting for the explanation of how (in your interpretation) sea-ice can proliferate if both sea and air temps are higher (on ave) than historically.

Very good question runrig. I know sea ice is proliferating because -
http://earthobser...id=82160

It's your cult that claims the globe is cooling because all the heat is suddenly going into the oceans, so I would toss your question right back at you.


As I said - observational evidence of warming seas and air in the Antarctic environment please.
Water_Prophet
1.8 / 5 (5) Aug 16, 2014
@runrig,
You da man!
Jim Spriggs
4.6 / 5 (10) Aug 17, 2014
The simulations suggest an "additional 1 to 37 centimeters in this century already".

First of all, really? They're making a prediction that Antarctic glacier melt could contribute essentially nothing all the way up to 37 centimeters in addition to current sea level rise? How many bookies guarantee you money if your horse comes in anywhere from 1st to 37th place? Silly. That's not a prediction; it's a blind guess.


You just cherry picked Anders Levermann's premise so you could concoct your own conclusion, aksdad.

For anyone else who's reading, here's Levermann's conclusion as stated in the article:

"Now this is a big range – which is exactly why we call it a risk: Science needs to be clear about the uncertainty, so that decision makers at the coast and in coastal megacities like Shanghai or New York can consider the potential implications in their planning processes."

I know you read the article, aksdad, so why did you imply he's making a specific prediction?
Jim Spriggs
4.6 / 5 (9) Aug 17, 2014
antigoracle says:
Oh, imagine the desperation of the AGW Cult to propagate this lie. The ocean is warm enough to melt the ice shelves but not the growing sea ice.


Science deniers' heads start hurting when their lock-step and linear world view is challenged by that of the complexity and seeming capriciousness of nature. Denying themselves of further study and denial of science seems to serve as relief from the pain.

antigoracle says:
It's your cult that claims the globe is cooling because all the heat is suddenly going into the oceans, so I would toss your question right back at you.


Straw man, antigoracle. Nobody on the side of science says the "globe is cooling" at all. It continues to warm in spite of 94% of the heat going into the oceans. 2005 and 2010 tied for the warmest years on record and, if trends continue, 2014 is expected to get even warmer.

Jim Spriggs
4.6 / 5 (10) Aug 17, 2014
aksdad says:
Global sea level rise is currently measured as 2.8 ± 0.8 mm/yr (tide gauges) to 3.2 ± 0.4 mm/yr (satellite altimetry). That rate hasn't changed significantly in the last 20 years.
At 3.2 mm/yr that works out to 32 centimeters a century, about 12.6 inches.
Secondly, where's the evidence that sea level rise is accelerating according to their predictions? There is none. See for yourself.


NOAA trumps aksdad's lame cherry picking and false extrapolation:

"While studies show that sea levels changed little from AD 0 until 1900, sea levels began to climb in the 20th century.
---
Records and research show that sea level has been steadily rising at a rate of 0.04 to 0.1 inches per year since 1900.
---
Since 1992, new methods of satellite altimetry indicate a rate of rise of 0.12 inches per year.
This is a significantly larger rate than the sea-level rise averaged over the last several thousand years."
http://oceanservi...vel.html
Jim Spriggs
4.6 / 5 (10) Aug 17, 2014
aksdad says:
And not all of the Antarctic ocean is warming; some is cooling. It's ironic that the favorite theory of alarmists is winds blowing sea ice around; a theory they reject about why the Arctic (North Pole) sea ice has been diminishing in the last 30 years. For example, see:

http://www.skepti...iate.htm


Full of baloney. First, your SKS link says nothing about arctic winds "blowing sea ice around." Second, scientists have NOT been rejecting the roll of winds in Arctic sea ice reduction. That's a straw man. You remember 2012, right?:
"Arctic sea ice melted to a record low level this past summer — surpassing a 2007 minimum — and a new study suggests that changes in wind patterns over the planet's northernmost region could be partially to blame."
http://www.livesc...ice.html

So your cry of "hypocrisy" among climate scientists is simply a distraction, and an offensive one at that.
runrig
4.5 / 5 (8) Aug 18, 2014
Excellent string of posts Jim.
antigoracle
1.5 / 5 (8) Aug 18, 2014
Science deniers' heads start hurting when their lock-step and linear world view is challenged by that of the complexity and seeming capriciousness of nature. Denying themselves of further study and denial of science seems to serve as relief from the pain.
-- Jim Spriggs
Oh, the chant of the AGW cultist, when posed with a question that exposes the absurdity of their dogma. If I did not find them amusing, I might actually shed a tear.
So, 94% of the heat is going into the oceans, which then melt the Antarctic ice shelves but not the much more exposed sea ice. The faith..er...stupidity is strong in this one.
aksdad
1 / 5 (4) Sep 08, 2014
NOAA trumps aksdad's lame cherry picking and false extrapolation

Have a look again at the sea level graph from satellite altimetry, 1993-present.

http://sealevel.colorado.edu/

The trend has remained the same. There has been no acceleration in sea level rise in the last 2 decades. That's not cherry-picking. There were no satellites measuring sea levels before 1993.

The interesting thing is that tide gauges show a lower rate of sea level rise since 1993 than do the satellites. Click on "Tide Gauge Sea Level" at the above link. Virtually all of the "acceleration" in sea level rise that occurred after 1992 is based on satellite measurements, not tide gauges. The tide gauges show essentially the same trend of the last 80 years. See here:

http://en.wikiped...EPA).png

Either way you look at it, there has been no acceleration of sea level rise in recent history.
aksdad
1 / 5 (4) Sep 08, 2014
From Jim's link to NOAA on sea level:

This (post-1992 satellite measured rate) is a significantly larger rate than the sea-level rise averaged over the last several thousand years

As noted above, satellites measure a higher rate than do tide gauges. Tide gauges cover a much longer time period. It should also be noted that satellites don't have sub-millimeter or even millimeter accuracy. The "measured" sea level rise is the result of statistical analyses involving a series of complicated adjustments.

The current rate may be higher than the average of the last several thousand years (or not), but it doesn't even come close to prehistoric rates of sea level rise or fall. And those changes happened long before humans arrived on the scene and tried to blame warming and sea level rise on human "greenhouse gas" emissions. No one knows why the planet cooled and warmed at rates much higher than current. If your theories can't explain the past, they won't predict the future.
aksdad
1 / 5 (4) Sep 08, 2014
It's important to note that Levermann's prediction of up to 37 centimeters sea level rise is based in part on warming predicted by CMIP-5 climate models. The global climate models have proved famously bad at predicting warming. The most recent IPCC AR5 demonstrates that the earlier CMIP-3 models all overestimate warming compared to measured temperatures:

http://www.climat...g1-4.jpg

The latest CMIP-5 models aren't much better, as seen here:

http://www.drroys...2013.png

When you base sea level rise predictions on model projections of ice loss which are in turn based on (poor) model projections of warming, you've got a mess.
aksdad
1 / 5 (4) Sep 08, 2014
Second, scientists have NOT been rejecting the roll of winds in Arctic sea ice reduction.

I didn't say "scientists", I said "alarmists". Alarmists blame it on human "greenhouse gas" emissions first and foremost despite abundant evidence that refutes the theory that human greenhouse gas emissions are the primary cause of global warming and climate change.

Remember that "97% consensus" paper by Cook et al. that claimed a survey of 11,000 scientific papers showed 97.1% agreed that humans are the primary cause of warming since 1950? It turns out that it was really 0.3%. The rest (97%) either took no position or the paper implied that humans may have caused "some" warming, which is the position most "climate skeptics" take. It is the alarmists that blame it all on human emissions while scientists take a more skeptical view: some warming may be caused by humans. How much that is remains to be determined, as the science is far from settled.