Stronger winds explain puzzling growth of sea ice in Antarctica
From University of Washington press room by Hannah Hickey
Much attention is paid to melting sea ice in the Arctic. But less clear is the situation on the other side of the planet. Despite warmer air and oceans, there’s more sea ice in Antarctica now than in the 1970s – a fact often pounced on by global warming skeptics. The latest numbers suggest the Antarctic sea ice may be heading toward a record high this year.
While changes in weather may play a big role in short-term changes in sea ice seen in the past couple of months, changes in winds have apparently led to the more general upward sea ice trend during the past few decades, according to University of Washington research. A new modeling study to be published in the Journal of Climate shows that stronger polar winds lead to an increase in Antarctic sea ice, even in a warming climate.
“The overwhelming evidence is that the Southern Ocean is warming,” said author Jinlun Zhang, an oceanographer at the UW Applied Physics Laboratory. “Why would sea ice be increasing? Although the rate of increase is small, it is a puzzle to scientists.”
This mixture of different types of Antarctic sea ice was photographed Oct. 13, 2012, by a NASA aircraft flying over the Bellingshausen Sea.
His new study shows that stronger westerly winds swirling around the South Pole can explain 80 percent of the increase in Antarctic sea ice volume in the past three decades.
The polar vortex that swirls around the South Pole is not just stronger than it was when satellite records began in the 1970s, it has more convergence, meaning it shoves the sea ice together to cause ridging. Stronger winds also drive ice faster, which leads to still more deformation and ridging. This creates thicker, longer-lasting ice, while exposing surrounding water and thin ice to the blistering cold winds that cause more ice growth.
In a computer simulation that includes detailed interactions between wind and sea, thick ice — more than 6 feet deep — increased by about 1 percent per year from 1979 to 2010, while the amount of thin ice stayed fairly constant. The end result is a thicker, slightly larger ice pack that lasts longer into the summer.
“You’ve got more thick ice, more ridged ice, and at the same time you will get more ice extent because the ice just survives longer,” Zhang said.
When the model held the polar winds at a constant level, the sea ice increased only 20 percent as much. A previous study by Zhang showed that changes in water density could explain the remaining increase.
“People have been talking about the possible link between winds and Antarctic sea ice expansion before, but I think this is the first study that confirms this link through a model experiment,” commented Axel Schweiger, a polar scientist at the UW Applied Physics Lab. “This is another process by which dynamic changes in the atmosphere can make changes in sea ice that are not necessarily expected.”
The research was funded by the National Science Foundation.
Still unknown is why the southern winds have been getting stronger. Some scientists have theorized that it could be related to global warming, or to the ozone depletion in the Southern Hemisphere, or just to natural cycles of variability.
Differences between the two poles could explain why they are not behaving in the same way. Surface air warming in the Arctic appears to be greater and more uniform, Zhang said. Another difference is that northern water is in a fairly protected basin, while the Antarctic sea ice floats in open oceans where it expands freely in winter and melts almost completely in summer.
The sea ice uptick in Antarctica is small compared with the amount being lost in the Arctic, meaning there is an overall decrease in sea ice worldwide.
Many of the global climate models have been unable to explain the observed increase in Antarctic sea ice. Researchers have been working to improve models to better reproduce the observed increase in sea ice there and predict what the future may bring.
Eventually, Zhang anticipates that if warmer temperatures come to dominate they will resolve the apparent contradiction.
“If the warming continues, at some point the trend will reverse,” Zhang said.
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The polar vortex that swirls around the South Pole is not just stronger than it was when satellite records began in the 1970s, it has more convergence, meaning it shoves the sea ice together to cause ridging.
This makes me wonder if this isn’t one of the reasons that the “ozone hole” continues, despite CFC reduction schemes. Of course the study is all model based, so it may not represent reality.
The Wack-a-Mole game survives in climate science. This time, winds that computer models inherently cannot model on a regional scale give an explanation for a badly wrong prediction about fundamental polar amplification in the Antarctic.
Another young Ph.D about to be sacrificed by the climate change high priests ( who even named themselves as such via satellite simulations back to 1860….on a highly visible PNAS platform) as another offering to their financing Gods.
Pardon the Inca and Mayan priests who did similarly. At least at that previous time, they did not know better. But now we do. There can be no pardon.
Truly settled science – no doubt. These guys should be de-funded. Immediately. Since the science was settled years ago there is no need for anymore work. Especially if it’s this quality. This must be embarassing for the scientists who follow the scientific method and make models that history match the facts.
Bob Tisdale says:
September 18, 2013 at 6:17 pm
Modeling study? Are the current batch of climate scientists incapable of studying data?
Oh, for the good old days before fatally flawed climate models.
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But data are so messy and sometimes don’t easily lead to the results you want. Models are much cleaner and don’t have the tendency to give the results you don’t expect.
The increase in Antarctic ice has been treated as a distraction when we had the ice-free Arctic to look forward to. When that began to look unlikely we were treated to ice-shelf melting and now wind modeling to explain it away. Seems like there may be some real science in there, but it is outweighed by political science.
I wonder if Zhang has ever been to Antarctica. i wonder if he has ever spent time working on the sea ice or on a ship sailing through it. No matter how strong or cold the wind, if the sea surface water is not cold enough it will not freeze and once it does freeze the wind has no effect on the thickening of the ice. That occurs by radiation of heat through the ice from the water underneath. Sea ice thickens by water freezing from underneath. But then you would think a scientist studying sea ice would know that wouldn’t you. Perhaps that is the difference between the armchair theorists and practical scientists.
By the way, is there any actual data on the circumpolar wind strength from sub Antarctic islands or is this just guess work on Zhang’s part.
Inland the Antarctic is cooling. Here is the proof.
http://data.giss.nasa.gov/cgi-bin/gistemp/show_station.cgi?id=700890090008&dt=1&ds=14
According to CO2 theory it should be warming faster than any other place on the planet except the north pole.
‘ “People have been talking about the possible link between winds and Antarctic sea ice expansion before, but I think this is the first study that confirms this link through a model experiment,” commented Axel Schweiger, a polar scientist at the UW Applied Physics Lab.’
Model runs, simulations, are not experiments. Model runs are scenarios. They amount to nothing more than a substitution of new values for familiar parameters or maybe a change in some differential equations prior to running the model. One learns nothing more than how those changes impact the outcome of the model run. Note that reality is missing from all this talk of model runs and simulations. Because there is no contact with reality there is no experiment. Experiments require real world results that can surprise one.
What Axel calls “a model experiment” is really wishful simulation.
Theo Goodwin + “… wishful simulation …”
Climate pscience researchers’ wish: father to the thought.
from Shakespeare – King Henry IV Part 2 (1597):
Prince Henry (Harry): I never thought to hear you speak again.
King Henry IV:
Thy wish was father, Harry, to that thought:
I stay too long by thee, I weary thee.
Perhaps sequester could result in NSF wasting less money on worthless “computer games” like this one. Why can not they just say, don’t have a clue, but need more money so as not to continue to be clueless.
They dont know why the sea ice is growing. Wind patterns is just as much a guess as the theory that it is due to the melting ice shelves cooling the adjacent waters.
A Professor currently working on the Ross Ice shelf wrote to me stating that the increased sea ice was due the the ozone hole allowing cold air from high above to descend on the Arctic ocean.
This increase is difficult to explain away in a warming world and I dont think they have found the answer yet.
Not sure if anything has changed of late, but here is an “Old sailor’s saying”:
“Below forty degrees south there is no law;
below fifty degrees south there is no God”
Antarctic, not Arctic….
You can simulate an actual experiment. There might be no reason to do so because you have the actual experiment. If the simulation is wrong you can discover that fact by investigating the actual experiment.
But can you simulate what Axel calls “a model experiment?” Wouldn’t that be just another run of Axel’s model? Like buying a second copy of your newspaper to confirm what you read in your newspaper. There is no independent reality there in Axel’s “model experiment.”
Besides the false claim that ice is growing where it is warming, the model actually offers a good explanation for the change in Arctic sea ice. Most of the Antarctic sea ice is driven by the katabaitc winds blowing equator-ward from the continental interior. Unconstrained by other continents, most of the Antarctcc sea ice expands unimpeded with much less ridging than witnessed in the Arctic. For that reason most of Antarctic’s sea ice is thin first year ice with very little ridging that is claimed by the model. Each winter the Antarctic sea ice extent is much greater than observed in the Arctic, but Antarctic sea ice also melts more rapidly each summer precisely because there is so little ridging .
In contrast, the Arctic Oscillation causes cycles that change the direction of the winds and indeed causes more ridging and thicker ice as the winds compress Arctic sea ice against the coastlines, and building thick multiyear ice that resists melting. When the AO switches phases the winds which blow that thick ice into the Atlantic The replacement ice is first year ice that behaves like the Antarctic melting quickly each summer. This model explain why there has been a cycle of rapid summer melt in the Arctic
http://landscapesandcycles.net/antarctic-sea-ice–climate-change-indicator.html
Of course, changes in arctic ice couldn’t be due to changes in wind, clouds , storms, PDO, AMO, etc – it must be CAGW, but the in the antarctic, it must just be winds – it couldn’t be that CAGW is wrong
/sarc off
These guys are so blind to the obvious , it’s really kind of amusing. What do you say to this , really? When data works the way you want , it’s CAGW, when it doesn’t it is “weather”. Truly delusional !
Stronger winds… must be this global warming reduced gradient… oooops. Not. Flush!
Really ?
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg
Tez says:
September 18, 2013 at 7:26 pm
They dont know why the sea ice is growing.
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That’s because “they” are a collection of frauds, idiots and liars.
Winds do impact ice sometimes. Some set records…….
http://www.nasa.gov/topics/earth/features/arctic-storm.html
One excuse after another
Theo Goodwin says:
But can you simulate what Axel calls “a model experiment?” Wouldn’t that be just another run of Axel’s model? Like buying a second copy of your newspaper to confirm what you read in your newspaper.
Close, but no.
What Axel calls a “model experiment” is not like buying a second copy of your newspaper to confirm what you read in your newspaper. It is like buying a second copy of your newspaper to confirm what you wrote in your newspaper.
Models are not experiments, they are hypotheses.
Models do not produce data, they regurgitate assertions.
Models cannot prove. They can only be proven. Or not. By data.
Is there an animated year by year satellite graphic of the Antarctic sea ice, like there is for the Arctic?
Scanned sea ice page quickly and couldn’t see one.
Tom
I am coming to the conclusion that the CAGW cartel (“warmist” is a term too benigh) is the perfect example of a codependent mob which can rationalize any scenario for the sake of the cause.
Funny. When storm winds contributed to the record low ice in the Arctic (was that last year?) it was ignored. Now winds are the excuse for record high ice in the Antarctic?
Oh Dear.
Stained bed sheets flapping in the wind, … yet again.
Models have their place. This model is being used to answer the reasonably simple question “can stronger winds lead to more ice”. The situation is non-chaotic and amenable to simplification. There are only a small number of parameters and these can be measured or checked, the equations are not bizarrely sensitive to initial conditions. I have absolutely no issue with this kind of model. It is the standard kind of thing that applied mathematicians do every day. Models are just a tool. Models don’t kill people. People kill people … whatever.
Zhang’s statement that
“The overwhelming evidence is that the Southern Ocean is warming” is contradicted by this recent paper :
http://www.hindawi.com/isrn/oceanography/2013/392632/ref/
by Maheshwari etal (2013) where the authors conclude
“From the time series analysis of the variation of Southern Ocean surface temperature anomalies, (1982-2011) a slightly negative (i.e., cooling) trend in average temperature anomaly over the entire region is obtained.”
If the very strong eastern southern ocean/Indian ocean positive anomaly is removed the decline would be quite significant. Rapid cooling in the Ross and Weddel seas is particularly strong.