Like Flipping a Switch: Antarctic Glaciers Sudden Race to Sea
May 22, 2015
“One of the warning signs that a dangerous warming trend is under way in Antarctica will be the breakup of ice shelves on both coasts of the Antarctic Peninsula, starting with the northernmost and extending gradually southward.”
John Mercer – 1978
Very good piece in the Christian Science Monitor explaining a new study of mass loss from a southern region of the Antarctic peninsula. We’ve been hit with a volley of devastating studies showing that “stable” Antarctic ice is much more sensitive to warming than most scientists thought a few decades ago.
The losses began suddenly in 2009 and come in addition to losses from the West Antarctic Ice Sheet, which is shedding 80 billion to 110 billion tons of ice a year, according to the study. Some losses from nearby ice shelves have been underway for decades. But the seemingly abrupt onset of significant ice losses along the southern coast of the Antarctic Peninsula is an eye-opener, suggests Dr. Gardner of JPL. Recent studies have shown that Antarctica’s two continental ice sheets are more sensitive to changes in ocean and air temperatures than previously thought, he notes. But as relatively warm water from deep reaches of the Southern Ocean moved onto the continental shelf, the thinning sped up, melting the ice shelves from underneath, the researchers of the new study concluded. – “It’s like a switch was flipped for a pretty extensive region of the peninsula,” adds Jonathan Bamber, a glaciologist at the University of Bristol in Britain and a member of the team conducting the study. “That isn’t something that you would necessarily expect based on the modeling studies that people have done.”
For most of the 2000s, satellite data shows the glaciers lost about as much ice as they gained, meaning they stayed roughly stable. But around 2009 there was “a remarkable rate of acceleration” in ice loss, the study says.
The red and orange areas in the figure below show thinning of glaciers along the Bellinghausen Sea coast. You can see the melting is much more rapid between 2010 and 2014 (right-hand image) than between 2003 and 2009 (left-hand image).
Change in glacier thickness between A) 2003 and 2009 and B) 2010 and 2014 in the Southern Antarctic Peninsula. Oranges and reds show areas of greatest thinning. Source: Wouters et al. ( 2015)
Several glaciers on the southern Antarctic Peninsula suddenly began shedding ice in 2009, satellite observations now reveal. The region has dumped the equivalent of 72 cubic miles of water—enough to fill 350,000 Empire State Buildings—into the ocean since then, researchers report today in Science. “The region changed from being quiet, in balance, to massive ice loss within a couple of years,” notes lead author Bert Wouters of the University of Bristol. “This is quite surprising, a complete shift of the dynamics in the area. It shows that the ice sheet can react very rapidly to changes in its environment.
Abstract – Dynamic thinning of glaciers on the Southern Antarctic Peninsula:
Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the Southern Antarctic Peninsula satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry is potentially unstable. We use satellite altimetry and gravity observations to show that a major portion of the region has, since 2009, destabilized. Ice mass loss of the marine-terminating glaciers has rapidly accelerated from close to balance in the 2000s to a sustained rate of –56 ± 8 gigatons per year, constituting a major fraction of Antarctica’s contribution to rising sea level. The widespread, simultaneous nature of the acceleration, in the absence of a persistent atmospheric forcing, points to an oceanic driving mechanism.
Climate Denial Crock of the Week 
May 22, 2015 at 9:16 am
is there a good general audience article that discusses the interaction between the record extent and the volume losses?
May 22, 2015 at 5:14 pm
Skeptical science has some “general audience” level articles—-here are two.
http://www.skepticalscience.com/Why-is-Antarctic-sea-ice-increasing.html
http://www.skepticalscience.com/antarctica-gaining-ice.html
There really isn’t any direct “interaction” as such between Antarctic sea ice extent increase and Antarctic land ice “volume” loss, other than that both appear to be changing because of AGW. Read the articles—-the ice extent is increasing because of LESS heat being brought up from the ocean depths because of salinity changes, while the accelerating glacial loss is due to MORE heat getting up under the edges of the glaciers and melting them from below.
May 23, 2015 at 1:04 am
Hi Ed, the best general audience descriptions I could find (discussing the interaction) is in this link Antarctic.Glaciers, by Dr. Bethan Davis glaciologist at University of London:-
“As the glaciers and ice shelves melt on the Antarctic continent, freshwater is added to the oceans. This layer of cold, fresh water on the ocean surface freezes easily [10]. When combined with increased ocean stratification due to this enhanced run off [11], sea-surface temperatures are depressed, encouraging sea-ice formation”
http://www.antarcticglaciers.org/glaciers-and-climate/ice-ocean-interactions/antarctic-sea-ice/
May 24, 2015 at 6:05 pm
And here is a more technical paper on the effect of fresh water melt on sea ice in the Antarctic:
Click to access a69a001.pdf
May 22, 2015 at 6:06 pm
This report in “Science Daily” explains findings that a beached ice berg has caused greatly increased sea ice in Commonwealth Bay, Antarctica, as well as other effects to the ecology of the bay. Recent reports suggest that Larsen B is in the final throws of decay and Larsen C is also on the way. With the disintegration of ice shelves we will see a lot more glaciers being launched and dramatics affects on the Antarctic sea ice (as well as ocean currents).
http://www.sciencedaily.com/releases/2015/05/150518102134.htm
The most dramatic recent news was that the “hot spot” in the Troposphere has been finally located. This fingerprint of AGW has long been predicted by models and now it is confirmed.
http://www.newsroom.unsw.edu.au/news/science-tech/climate-scientists-find-elusive-tropospheric-hot-spot
Interestingly Anthony Watts, one of the leading deniers, can only try and discredit the University that discovered the hot spot, by referring to the “ship of fools” incident (where a research ship became stuck in Antarctic sea ice). He is shown to be the biggest and dumbest fool around.
May 22, 2015 at 10:50 pm
The “missing tropical hot spot” has been something of a denier red herring, from what I understand. It never was a signature of greenhouse gas warming to begin with, but something expected with any global warming.
May 23, 2015 at 9:55 am
We have over 7.2 billion people on the planet today and not one wise leader among us can be found with the foresight and requisite leadership skills to provide anticipatory guidance. Neither a Nero can be located fiddling in a tower nor a Napoleon waiting at Waterloo. We have named our species Homo sapiens sapiens, but where are “the wisest of the wise” among us? Will a wise leader please stand up! The potential leaders I see are running off in mad frenzy pursuing only one thing……money. Can ‘flying for the buck’ be the wisest thing to be doing in our time? Or have the wisest of the wise taken flight aboard private jets, heading in different directions with plans to ravage the Earth on one fool’s errand after another? All leading members of the last generation with the power to change course, to do something that makes a difference with regard to climate change, biodiversity loss, pollution and extreme poverty.
May 25, 2015 at 5:23 am
[…] century, perhaps most notably sea level rise. Another area of glaciers once thought to be stable has fallen to the human CO2 spike which is occurring 14,000 faster than natural processes and 10-200 times faster than the PETM […]
May 31, 2015 at 10:52 am
[…] century, perhaps most notably sea level rise. Another area of glaciers once thought to be stable has fallen to the human CO2 spike which is occurring 14,000 faster than natural processes and 10-200 times faster than the PETM […]
June 7, 2015 at 6:51 pm
[…] century, perhaps most notably sea level rise. Another area of glaciers once thought to be stable has fallen to the human CO2 spike which is occurring 14,000 faster than natural processes and 10-200 times faster than the PETM […]