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 bottom line is this: global warming reduces sea ice in the Arctic, but global warming increases sea ice in the Antarctic. Is there anything that global warming can not do? The models say…. NO!
JJ says:
September 18, 2013 at 7:59 pm (replying to)
Theo Goodwin says:
I would extend that analogy a little further.
IF you bought a different newspaper, and then looked for the same event as “verification”, you’d have a little better “test” of the conclusion you got from your own “model” right? Not really, if you have deliberately selected what you are looking for, and have not done an independent check against biases. (During WWII, you would have found and read another Allied paper, and did not look for German or Japanese sources. You did not read the Communist internal party memo to find out what they wanted you to know.)
But, if that second newspaper used the same reporter as the first, does reading a story from AP twice actually “verify” any information? If you do not go read it also from AP, UPI, and the Christian Science Monitor and the Wall Street Journal, you have not checked your result. (And, even then, you’ve only read the CAGW-tinged data anyway!) If the six different writers all have only repeated identical words from the same speaker from the same press conference, you have not checked your data.
Worse, because you have been involved in “testing” the script of each equation at each stage of your model “experiment” you CANNOT verify your own model. Ever.
Remember always the courage of Rutherford’s decision to accept the experimental results showing a cannon shell had been fired at tissue paper, and had bounced off! he KNEW that the result was impossible. He KNEW his “model” of the atom prevented any such thing from happening – and his peers knew that result as well as he did But he continued to investigate the “impossible” result.
RACookPE1978 says:
September 18, 2013 at 6:28 pm
OK. Yeah. Right. Sure. Whatever. (If two lefts make a right, and two negatives multiply to make a positive, don’t four rights make a climate model more correct?)
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I read somewhere that it was 3 lefts and one bi-polar right, or something like that. Can’t remember where I read that, though.
Wow. History. I read Bob Illis’ comment that the Southern Oceans had not warmed for 100 years, and that seemed wrong. I did a little digging, and discovered a remarkable WUWT thread from about three years ago, “Dr. Curry warms the Southern Ocean”, in which this issue was discussed at length. And I was reminded that I participated in that thread, and offered SEVERAL references indicating the Southern Ocean was warming. My references were only mildly considered, and they were dismissed with quite inadequate effort, because the principal in that thread was hunting bigger game than I, a small fish to fry. Nonetheless, the references remain, and they are quite compelling that the Southern Ocean is warming. I note that one key paper, which I provide the citation and link to below, was not addressed at all in that somewhat forgotten thread. So I’ll also provide the abstract for that one.
Gille, Sarah T., 2008: Decadal-Scale Temperature Trends in the Southern Hemisphere Ocean. J. Climate, 21, 4749–4765. doi: http://dx.doi.org/10.1175/2008JCLI2131.1
http://journals.ametsoc.org/doi/abs/10.1175/2008JCLI2131.1
Long-term trends in the heat content of the Southern Hemisphere ocean are evaluated by comparing temperature profiles collected during the 1990s with profiles collected starting in the 1930s. Data are drawn both from ship-based hydrographic surveys and from autonomous floats. Results show that the upper 1000 m of the Southern Hemisphere ocean has warmed substantially during this time period at all depths. Warming is concentrated within the Antarctic Circumpolar Current (ACC). On a global scale, this warming trend implies that the ocean has gained heat from the atmosphere over the last 50 to 70 years. Although the data do not preclude the possibility that the Southern Ocean has warmed as a result of increased heat fluxes, either into the ocean or within the ocean, in general the strong trend in the Southern Ocean appears regionally consistent with a poleward migration of the ACC, possibly driven by long-term poleward shifts in the winds of the region, as represented by the southern annular mode.
So I think it’s fairly clear that the Southern Ocean has been and is warming, and efforts to understand the slight increase in Antarctic sea ice extent need to incorporate that.
If you took all of these desperate studies, this one and Ben Santer’s amazing satellites-over-Stonewall-Jackson paper and so on, and put their authors up in front of a group of taxpayers to justify their existence, you’d get a lot of bafflegab that when played backward would sound a lot like ‘We know what we’re doing now JUST GIVE US THE BLOODY MONEY’.
Theo Goodwin says:
September 18, 2013 at 7:19 pm
What Axel calls “a model experiment” is really wishful simulation.
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“wishful simulation” is a great phrase. I will remember to use that when talking elsewhere.
Over the last several weeks, I have steadily used the Arctic summer record combined with the Antarctic sea ice record to befuddle many a warmist. They do not know how to counter, so they mostly end up saying “what difference does 1 year make?”, or “that doesn’t matter”. The solar changes, on top of the polar data, is another great talking point to make a warmist choke up a bit.
Oakden Wolf says: September 18, 2013 at 8:26 pm
Wow…
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Your timeframe 1930-1990 does not match the satellite records timeframe 1979-today. Therefore your logic is false.
Cooling surface air temperatures since 1979 correlate well with increasing sea ice.
[url]http://notalotofpeopleknowthat.wordpress.com/2013/08/17/study-finds-antarctic-sea-ice-increases-when-it-gets-colder/[/url]
Also, all of Antarctica have been cooling since 1980.
http://wattsupwiththat.com/2009/02/28/steigs-antarctic-heartburn/
The Roaring Forties have had some really intense storms
this winter (it’s winter in the Southern Hemisphere) with
pressures down around 930 hp to 940hp. I can’t remember seeing
them quite that low that often before. The isobars are also very crowded
indicating strong winds.
If this is what it was like for the sailing ships from Europe during
the middle of the 19th century, it’s little wonder so many were lost.
If you want to watch for yourself see http://metservice.com and look
for the surface pressure maps. The Southern Ocean runs under
New Zealand. Anything higher than 960hp is just a squall for the
Southern Ocean.
Oakden wolf said:
So I think it’s fairly clear that the Southern Ocean has been and is warming, and efforts to understand the slight increase in Antarctic sea ice extent need to incorporate that.”
Not since 1982 :
http://www.hindawi.com/isrn/oceanography/2013/392632/ref/
It is interesting that there are strong regional interdecadel variations.
sophocles says:
September 18, 2013 at 8:50 pm
If you want to watch for yourself see http://metservice.com and look
for the surface pressure maps. The Southern Ocean runs under
New Zealand. Anything higher than 960hp is just a squall for the
Southern Ocean.
++++++++++++++++++++++++++++++++++++++++++
All that wind has taught us Kiwis how to sail flying catamarans fast. 🙂
The University of Washington ‘lives’ by the climate and other models, and so thus, it will perish … and NOT soon enough !
Still on topic. Tim Flannery the head of the now defunct Climate Commission here in Oz has just lost his $AUD180,000 year job and our new government is rapidly dismantling his old department.
Increasing sea ice, increasing Antarctic ice mass and melting of the floating ice sheets are all explained by a cooling Antarctica causing increased katabatic winds. And it does seem most of Antarctica is cooling.
Also, most of the new sea ice is around the Antarctic Peninsula, indicating the warming found there in the late 20th century was natural variation.
The opinion of a non-scientist.
The questions seems simple to me. How does sea water turns into ice? How does it melt?
Is it the atmosphere above the sea water that lowers surface water temperature and causes the surface water to freeze or, carried by currents, does colder water from below (released from the conditions greater depth creates) freeze upon reaching the surface? (Or does water with less salt content arrive at the surface and freeze more readily?)
How does sea ice thicken? It can’t thicken from the top since there is no sea water above the ice — so it must thicken from the bottom. Is it that the sea ice itself is colder than the water below it and thus thickens by converting that sea water below it into ice — or is much colder lower water (or less salty water) rising out of the depths (when released from deeper conditions) turn into ice as it approaches the surface?
Interestingly, we might ask the opposite question. How does sea ice turn into sea water? Does it melt from the top down or from the bottom up? Again is it air temperature above or warmer water temperature below that melts ice? Or is it black soot accumulation on the surface that causes greater absorbing of sunlight that causes ice to melt?
The thing that causes sea ice to form might NOT be the same thing that causes sea ice to melt.
Growing up in New Jersey (alright don’t mock me) I noticed that in cold winters ice formed on pier supports above the water level. The splash from waves froze if the air was cold enough. A bay (rarely) would freeze over if the air was cold enough (very little water circulation in a bay).
This is getting long winded.
If you were to asked me I would say that sea water freezes from the top down and melts from the bottom up. Soot on the surface ain’t that big a deal.
What freezing is going on in the Antarctic is caused by lower air temperatures and what “de-icing” is occurring is caused by a change in ocean currents (screw the volcano).
What freezing is going on in the Arctic is caused by lower air temperatures and the melting that was going on was caused by a shift in ocean currents bringing in warmer water.
The earth is big and small shifts in things (CO2, volcanoes, soot, etc.) are largely irrelevant.
Air temperature changes (for whatever reason) can cause cosmetic changes in the earth surface but the oceans stabilize the earth.
In the long long term the force that overrides all others is the varying input of the sun.
Anyway, that is what I conclude after reading WUWT for a number of years and doing my own thinking. Those are the opinions that I, a non-scientist, hold.
Of course, who cares? But hearing from the peanut gallery every once in a while won’t kill you.
(Trivia question — where does “peanut gallery” come from? What made it a popular term once upon a time? You will date yourself if you know the answer.)
Eugene WR Gallun
All I know is today is the day that Tim Flannerry got fired. “climate change is real” . “blub blub blub”. Go tell someone who cares Tim. A sad day for idiots.
“Overall, the Arctic has lost about 40% of its sea ice cover since 1980. Most scientists believe the ocean at the north pole could be entirely ice-free in the summer by the middle of the century – if not sooner.”
Most Scientists? They never named a single one…
So since the ice-free by 2013 didnt play out, they are moving it to 2050.
http://www.theguardian.com/environment/2013/sep/18/arctic-sea-ice-shrinks-record-low
So the 2012 Arctic sea ice minimum was a result of dangerous global warming, but the 2013 record Antarctic sea ice extent is “wind”?! I call BS on that.
The strong katabatic winds blowing offshore in Antarctica are because its so bloody cold there, for the same reason that trade winds are strengthened at the Equatorial Pacific during a La Nina due to the upwelling cold water off Peru.
Bill Inis says: The inconvenient truth is the Antarctic sea ice at (close to) record levels has to be explained by the warmers and there is no physically-logical reason why more wind would make the sea ice grow to a record.
Only “cold” water can make water freeze.
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Radiative heat loss and evaporative heat loss can contribute to such cooling. Compacting of ice by stronger winds will leave more area exposed, evaporation IIRC is proportional of square of wind speed.
I think this is what Zhang’s model experiment demonstrates.
Both these effects run counter to much cited ‘albedo feedback’. The trivial idea that less snow reflects less sunlight is only half the story.
Positive feedbacks are not much in evidence in the Arctic.
http://judithcurry.com/2013/09/16/inter-decadal-variation-in-northern-hemisphere-sea-ice/
phlogiston, well done. Don’t forget the undersea volcanic vents, and how there was a large break in sea ice some years ago, not from global warming, but another rogue sea ice chunk, knocked it off. No global warming, no danger to shipping, but the alarmists grabbed it to prove their climate change theories. BS X 1000.
So more wind = more ice now ??? More wind at the North Pole will cause it to have record extents ??? I thought high winds in the Arctic in 2012 caused minimum extent ??? Guessing ?? Propagrandizing ??? Picking at straws ?? Blowing more hot air ?? Probably. These guys today that call themselves “scientists”, brother!
@markx
“the increased Antarctic sea ice is caused by the melting Antarctic ice cap.”
That’s what I’ve been told as well. Somehow the air above the land is warm enough to melt the ice cap, but the more Northerly air (closer to the tropics) above the sea is cold enough to freeze the sea. I don’t understand how that works, but I’m not a climate scientist.
James Fosser says:
September 18, 2013 at 9:33 pm
“Still on topic. Tim Flannery the head of the now defunct Climate Commission here in Oz has just lost his $AUD180,000 year job and our new government is rapidly dismantling his old department.”
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Worth repeating…
As we all know the proponents of AGW do anything to keep their religion alive. This includes the presentation of made up arguments to cover up inconvenient truth’s that their entire claim is as dead as can be. They have become the real deniers.
http://stevengoddard.wordpress.com/2013/09/19/climate-scum-continue-to-ramp-up-the-lies/
Colder temperature –> Stronger katabatic winds –> increased sea ice extent
Shorter : increased sea ice extent <– Colder temperature
QED 😉
It is darkly amusing that the same steig-fueled stuff was said with the opposite spin about the Arctic… that winds had nothing to do with the sea ice extent reduction… it was just the temp as measured by the stations 1800 km away.
Funny how the same mechanism is capable of doing different things at different ends of the earth. What surprises will the old earth bring us next?