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.
There was much talk in 2007 and 2012 that the notable minima were ‘only’ because of the storms. I’ve seen similar claims this year that it’s only a less dramatic minimum because of winds preventing ice from dispersing.
Everyone finds a freind in the wind.
Maybe these atmospheric effects are the origin of the repetitive pattern I’ve noted.
http://judithcurry.com/2013/09/16/inter-decadal-variation-in-northern-hemisphere-sea-ice/
Reminds me of the experiment where a glass of warm water and a glass of cold water are placed in a fridge freezer. Which one do you think freezes first ?
And we’ve been studying the hole in the ozone layer for how long? Which makes us real experts on it right? So we can blame winds on the presumably growing hole? Right.
So you get more ice because you get more ice. The same kind of circular reasoning involved in using a computer simulation to verify a model.
Greg says:
September 18, 2013 at 10:25 pm
…
Both these effects run counter to much cited ‘albedo feedback’. The trivial idea that less snow reflects less sunlight is only half the story.
Remember that in the Antarctic albedo and cloud work opposite to everywhere else; Antarctic snow is so Daz automatic whiter than white that its albedo is greater than that of cloud. So in Antarctica, reduced cloud cover means more albedo, not less.
I wonder why?
[My capitalization]
What is one to make of these multiple projections? We can never find them wrong. We can never falsify their dire projections / predictions or whatever. No wonder people yawn and laugh, this is becoming a cat and mouse game of a joke.
I have a much simpler explanation:
When the Arctic ice was at an “all time” low it was blamed on wind. Now we know where the wind has blown all that ice to.
Obvious really.
Just to confirm, NSIDC show the Antarctic sea ice extent hit an all time high this week.
http://notalotofpeopleknowthat.wordpress.com/2013/09/17/antarctic-sea-ice-extent-breaks-all-time-record/
And all produced from the safety of their warm offices in front of a computer. Well done for a brilliant fairy story.NOW GO SOUTH AND DO SOME MEASUREMENTS IN REALITY. (shouting off)
Paul Homewood Just to confirm, NSIDC show the Antarctic sea ice extent hit an all time high this week.
Not according to this.
http://arctic.atmos.uiuc.edu/cryosphere/antarctic.sea.ice.interactive.html
These sort of papers are not serious studies or scientific work. They are little better than fairy stories created to mollify the Warmist audience seeking reassurance that it has not been wasting its time of pure fantasies.
Simon:
Your post at September 19, 2013 at 2:58 am says in total
According to your link, you and Paul Homewood are both right.
Definitions, dear boy, definitions.
Your link (which I have copied) shows the Antarctic sea ice extent hit an all time high for day 236 of 2013 which is in “this week”.
Since then the Antarctic sea ice extent has been slightly below 2007 levels and seems unlikely to be greater during 2013 than it was at maximum extent in 2007.
What your link actually and undeniably shows is
(a) Antarctic sea ice extent has large day-to-day variability
and
(b) there is no indication of a trend of reducing Antarctic sea ice extent over the years for any time of year.
Richard
Why do they keep insisting it is warming in places it obvioulsy is not?
I am now more convinced than ever that AGW ‘science’ in whichever branding it appears is completely and utterly and unfalsifiable. Just like the God of the gap’s. AGW’s missing heat or extra cold keeps on moving into areas of little understanding or lack of opservational data. Unfalsifiable
“If the warming continues, at some point the trend will reverse,” Zhang said.
But the trend is during warming, so it would take a cooling globally to reverse the trend, e.g. like at the 8.2Kyr event when temperatures rose in the Antarctic.
“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.”
Interesting statement, most people don’t argue with this part: “The overwhelming evidence is that the Southern Ocean is warming,” even when it is not true because they concentrate on arguing with the theory of stronger winds increasing ice area. To the non-technical the southern ocean must be warming. Therefore it is easier to get more research money and the oceans warming sea-level rising story continues.
“The research was funded by the National Science Foundation.”
It shows. Unfortunately.
Haven’t these guys ever heard of epicycles? The model doesn’t work (geocentric universe) so let’s invent epicycles to make up for the lack of fit. It will be interesting to see if the current theory of climate science becomes known as Ptolemaic climate science.
Pure nonsense. Almost all sea ice in Antarctica is thin and melts every summer. The only area with thick semi-permanent ice is in the Weddell sea, which is also almost the only area where the ice cover hasn’t expanded (the red area at the upper left in the map above).
Here are the official Sea Surface Temperature anomalies around Antarctica (starting at 55S about the tip of South America a good distance from where the sea ice starts) from 1854 to Aug 2013.
Let’s not have any more musing about the oceans around Antarctica warming.
http://s15.postimg.org/nws6fmyaz/SSTs_Around_Antarctica_1854_Aug2013.png
It is appalling that this paper even passed pal, I mean peer review, and the same can be said about the recent study, “Human and natural influences on the changing thermal structure of the atmosphere” by Santer and Painter, et al.
Sea water freezes at -2C. It will not freeze at any temperature higher than that. Wind chill or speed is not a factor in making water freeze. If wind is pushing the ice up to be thicker then that suggests that without the wind the Antarctic Ice Extent would or should be greater than it is. Considering Antarctica was only discovered just under 200 hundred years ago and the precision and amount of measurement has increased exponentially, then the increase in wind speed could be a factor or more people doing more measurements. Anyway, I understand the winds to be Katabatic and caused be cold air sinking and falling off the Antarctic land mass. This falling air coming off Antarctica will be turned to the right by the earth’s rotation producing the famous winds that the seas around Antarctica are famous for. Therefore, if the winds are increasing then there must be more cold air falling of that continent. And this is produced by warming?
Here are the official Sea Surface Temperature anomalies around Antarctica (starting at 55S about the tip of South America a good distance from where the sea ice starts) from 1854 to Aug 2013.
Wow, that is really interesting. Antarctic temperatures follow the general warming trend of the mid-20th century right up to the 1998 ENSO that pulsed the GAST and LTT up, overall, but have distinctly fallen since and lack the uptick seen elsewhere! It would be once again interesting to see this curve with error bars, of course, because the earlier temperatures in the series have to come from seriously inadequate sampling and inconsistent and poor measurement technique — Antarctica was real terra incognita until the mid-20th century, and Antarctic waters were and remain among the world’s most dangerous.
Taken at face value, though the pattern actually rather strongly suggests — to me — that heat was indeed steadily accumulating in the southern oceans in the latter half of the 20th century, but the nonlinear chaotic system of ocean currents and air currents hit a tipping point, dumped a huge bolus of that heat into the atmosphere all at once (in the super-ENSO event), and in the process self-organized into a new pattern of currents that cooled more efficiently — evidence of large scale negative feedback in the climate system. Since then, in the new pattern, the Antarctic and southern ocean has been neutral to cooling in the polar regions, heat has been concentrated more in the tropics, which is overall neutral to cooling as higher high/tropical temperatures cool much more efficiently over a much larger area than higher polar temperatures.
The arctic circulation is lagging in this same pattern — when the PDO shifted, it started a cooling trend in the northern pacific, but the NAO has yet to shift phase. If the Arctic Oscillation tightens up and decreases warm air/water mixing from the tropics, the arctic will also cool quickly and with it northern Europe, Siberia, Canada, and higher north latitudes. Or, perhaps the pattern won’t shift.
What many people do not realize is that the Earth can warm or cool significantly due to NOTHING BUT alterations in global transport of heat. Heat transport that leads to more tropical/polar mixing is globally warming. Heat transport that reduces the mixing is globally cooling. Shift the Gulf Stream a few hundred miles to the south in the global thermohaline circulation and both the NE US and Canada and Western Europe go into the deep freeze.
All of the major decadal oscillations have warming vs cooling effects depending on their (different) phases. Major warming can occur simply due to a coincidence in phase such that warming/mixing trends heterodyne. So can major cooling trends. We do not really know how to predict the behavior of these oscillations (especially e.g. ENSO, with its comparatively short and erratic period). Chalk it all up to yet another thing that we do not understand or have good long term data on.
rgb
Stephen Skinner says:
September 19, 2013 at 6:11 am
“….. This falling air coming off Antarctica will be turned to the right by the earth’s rotation producing the famous winds that the seas around Antarctica are famous for…..”
OK. Thats not correct is it? Should have known I was in the southern hemisphere. Looks like the cold air falling off Antarctic is pushed to the right by the prevailing Westerlies and if they are increasing that will be driven by weather systems to the north.
Climate scientists don’t understand the differences between experiments, the physical climate and models. How can we believe anybody who lacks a fundamental understanding of science?