Antarctic sea ice today from the University of Bremen, on track for a new record high this year:
From Georgia Tech’s Judith Curry:
“Our finding raises some interesting possibilities about what we might see in the future. We may see, on a time scale of decades, a switch in the Antarctic, where the sea ice extent begins to decrease…”
Resolving the paradox of the Antarctic sea ice
While Arctic sea ice has been diminishing in recent decades, the Antarctic sea ice extent has been increasing slightly. Researchers from the Georgia Institute of Technology provide an explanation for the seeming paradox of increasing Antarctic sea ice in a warming climate. The paper appears in the Early Edition of the Proceedings of the National Academy of Science the week of August 16, 2010.
“We wanted to understand this apparent paradox so that we can better understand what might happen to the Antarctic sea ice in the coming century with increased greenhouse warming,” said Jiping Liu, a research scientist in Georgia Tech’s School of Earth and Atmospheric Sciences.
For the last half of the 20th Century, as the atmosphere warmed, the hydrological cycle accelerated and there was more precipitation in the Southern Ocean surrounding Antarctica. This increased precipitation, mostly in the form of snow, stabilized the upper ocean and insulated it from the ocean heat below. This insulating effect reduced the amount of melting occurring below the sea ice. In addition, snow has a tendency to reflect atmospheric heat away from the sea ice, which reduced melting from above.
However, the climate models predict an accelerated warming exceeding natural variability with increased loading of greenhouse gases in the 21st century. This will likely result in the sea ice melting at a faster rate from both above and below. Here’s how it works. Increased warming of the atmosphere is expected to heat the upper ocean, which will increase the melting of the sea ice from below. In addition, increased warming will also result in a reduced level of snowfall, but more rain. Because rain doesn’t reflect heat back the way snow does, this will enhance the melting of the Antarctic sea ice from above.
“Our finding raises some interesting possibilities about what we might see in the future. We may see, on a time scale of decades, a switch in the Antarctic, where the sea ice extent begins to decrease,” said Judith A. Curry, chair of the School of Earth and Atmospheric Sciences at Georgia Tech.
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Judith Curry: About the paper, since ENSO and AAO are the driving forces of Antarctic climate, I assume your models include ENSO. Are you assuming the frequency and amplitude of ENSO events are increasing during the 21st century? Are you assuming that NINO3.4 SST anomalies (or whatever related index you’re using) are increasing?
Somewhat on topic: As an Antarctic researcher, I’m sure you’ve had occasion to look at the ERSST.v3b version of the Southern Ocean SST data. It differs significantly from the HADISST data prior to 1960. (Over that period, the HADISST Southern Ocean data looks to be little more than occasional inputs on top of the climatology). If you have examined the ERSST.v3b data, have you come up with any explanation for that unique ERSST.v3b Southern Ocean curve, which shows a negative trend over the term of the data?
http://i34.tinypic.com/20s828o.jpg
And based on the next graph, would you have any explanation for the difference between the SST anomalies of the Southern Ocean south of the Pacific and those south of the Atlantic and Indian Oceans?
http://i38.tinypic.com/2u3v0pz.jpg
Last question: I ran across a paper a couple of years ago that was a reconstruction of Antarctic Sea Ice from the late 1800s to the late 1900s that appeared to be an inverted version of the ERSST.v3b Southern Ocean SST anomaly data, showing a long-term increase in Antarctic sea ice. Do you recall the paper?
Ed Caryl says:
August 17, 2010 at 6:15 am
I learned one thing here. Ignore Judith Curry!
———
Good luck getting your paper accepted Dr. Curry. The establishment seems to have turned on you, as they do to anyone who stops drinking the kool air and worshiping at their altar, even if only temporarily.
Judith Curry wrote, “The observed sea surface temperatures in the Southern Ocean shows an overall increase during the period 1960-present.”
It depends on the dataset. ERSST.v3b shows a slight positive trend of 0.004 deg C/ decade for the Southern Ocean (90S-60S) and HADISST shows a negative trend of
-0.007 deg C/decade.
http://i35.tinypic.com/10dboyp.jpg
Bob Tisdale:
Great graphs Bob.
[ http://i34.tinypic.com/20s828o.jpg & http://i38.tinypic.com/2u3v0pz.jpg ]
The HADISST version of the Southern Ocean record is humorous.
Also: Great questions you’ve posted for Dr. Judith Curry.
I encourage all to consider that EOP (Earth Orientation Parameters) tell more about the Southern Ocean than anthropogenic computer fantasies based on untenable assumptions.
Here’s some reference material for those interested:
Sidorenkov, N.S. (2005). Physics of the Earth’s rotation instabilities. Astronomical and Astrophysical Transactions 24(5), 425-439.
http://images.astronet.ru/pubd/2008/09/28/0001230882/425-439.pdf
Sidorenkov, N.S. (2003). Changes in the Antarctic ice sheet mass and the instability of the Earth’s rotation over the last 110 years. International Association of Geodesy Symposia 127, 339-346.
Sidorenkov, N.S. (2005). The decade fluctuations of the Earth rotation velocity and of the secular polar motion. In: Journees 2004 – systemes de reference spatio-temporels. Fundamental astronomy: new concepts and models for high accuracy observations, Paris, 20-22 September 2004, edited by N. Capitaine, Paris: Observatoire de Paris, ISBN 2-901057-51-9, 2005, p.153-154.
http://syrte.obspm.fr/journees2004/PDF/Sidorenkov.pdf
That’s just the beginning of the story.
Thanks for the clarification, Bob. I suppose I should have said whatever mechanism that causes the PDO to peak and trough every thirty odd years
Dr Curry,
Not having access to the paper, I am asking some questions out of ignorance. If the added ice extent due to GW in the Antarctic is thin, even given the increased winter extent, wouldn’t the minima show either a constant value or reduction? they seem to be increasing like the maxima which would imply multiyear ice is building up. Is this explained by your theory?
Why does the NH differ from the SH? Basin vs ocean surrounded land mass? Shouldn’t the same effect apply to both? Should we expect to see greater winter ice extent outside of the Arctic Basin based on the same effect?
“Our finding raises some interesting possibilities about what we might see in the future. We may see, on a time scale of decades, a switch in the Antarctic, where the sea ice extent begins to decrease…”
———
We will see, ” on a time scale of decades, a switch in the Antarctic, where the sea ice extent begins to decrease…”
Bi-polar seesaw
http://www.nature.com/nature/journal/v457/n7233/full/4571093a.html
http://www.sciencedaily.com/releases/2006/11/061109130709.htm
http://pielkeclimatesci.wordpress.com/2010/04/26/new-paper-twentieth-century-bipolar-seesaw-of-the-arctic-and-antarctic-surface-air-temperatures-by-chylek-et-al-2010/
“Our finding raises some interesting possibilities about what we might see in the future. We may see, on a time scale of decades, a switch in the Antarctic, where the sea ice extent begins to decrease…” (From Georgia Tech’s Judith Curry)
At least on this point we are all agreed. What goes up must (usually) come down.
Dr Curry:
This “news release” is an example of modern journalism and PAO-manship at its most pathetic. Whoever put this thing to paper and on the web should have been fired a week before it was ever typed. If the intent was to be clear and concise, it was only concise. It makes GT and you and your collegues look and sound totally inept. I look forward to reading the actual study and finding out what it was your Public Affairs Office was trying to actually describe. Better luck next time!
Barry W, you ask good questions. There are a number of differences between the Arctic and Antarctic sea ice. Most of the Antarctic sea ice melts during summer, whereas much of the sea ice in the Arctic survives the summer melt season. Hence, you can have much thicker multi-year ice in the Arctic (up to several meters thick), whereas Antarctic sea ice is almost all first year, with maximum thickness less than 1 m. Also, the ice concentration (fraction of ice) in the antarctic is typically about 80% during local winter, whereas in the Arctic (away from the marginal ice zone in the north Atlantic) has a concentration of >95%; this a function of landlocked ice in the Arctic vs unconstrained ice in the Antarctic.
We will get the paper posted on my website tomorrow, i will let you know the location.
Actually the paper is already posted on my web site here is the link (note this is in manuscript form, not the PNAS formatted version)
http://www.eas.gatech.edu/files/jiping_pnas.pdf
>> Bob Tisdale says:
August 17, 2010 at 4:43 pm
Judith Curry wrote, “The observed sea surface temperatures in the Southern Ocean shows an overall increase during the period 1960-present.”
It depends on the dataset. ERSST.v3b shows a slight positive trend of 0.004 deg C/ decade for the Southern Ocean (90S-60S) and HADISST shows a negative trend of
-0.007 deg C/decade.
http://i35.tinypic.com/10dboyp.jpg <<
Nice graph Bob. I somehow doubt that the .004 deg C / decade is sufficient to drive the model used in this paper.
I do, however, question temperatures before 1979. If you limit the trend to just the (presumable much more accurate and comprehensive) measurements of the satellite era, the SST trend is very negative and there's no 'paradox.'
George: I did not mean you when I said coalesce. You know this stuff.
There are no monsoons in Antarctica. The sparse moisture that arrives stays for almost ever in place. A lot of the interior is cold desert. The blizzards we see there are “dry” blizzards with very fluffy snow and high winds that make it “real”.
Judith says there are many ways to say how much ice extent anomaly there is. Only the absolute amount of ice, not percentages up or down, is relevant to global warming debate, sea levels rising, etc. Using % is disingenuous at best, and shows her bias.
Judith Curry says:
August 17, 2010 at 2:06 pm
Lucy VC, not interested in mercy. Still scanning for some thoughtful questions that I will respond to.
—————-
Bob Tisdale,
Please don’t take offence. Judith did not say that she would respond to ALL thoughtful questions.
It was good of her to spend time responding to Lucy, I thought.
Eric Anderson said:
August 16, 2010 at 9:29 pm
“Also, how does snow falling on top of the ocean “stabilize it from the ocean heat below”?”
Reading the paper it makes it less saline so heat is not transferred as much to the more weakly stratified layers.
Dr Curry ( Prof?) thanks for putting the link to your paper it was an interesting read. (thumbsup)
A question related to the southern ocean, as well as the SST going up by 0.2C and perhaps more snowfall/rain is the wind speeds also increasing?
Andy
tty says:
August 17, 2010 at 7:30 am
Perhaps not entirely OT: Cryosphere’s sea-ice curve for Antarctica just went off the chart
Hehehe, I just noticed it this morning. Priceless. I was about to write about it but you came in first 🙂
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.recent.antarctic.png
Tom_R: You wrote, “I do, however, question temperatures before 1979. If you limit the trend to just the (presumable much more accurate and comprehensive) measurements of the satellite era, the SST trend is very negative and there’s no ‘paradox.'”
Agreed. I only started the graph in 1960 because Judith used it in her comment. And I just downloaded a copy of the paper Judith linked and noticed they used ERSST.v2 in the paper, not ERSST.v3b, so I’ll have to rerun the trend graph, but ERSST in either version is not satellite based.
Oops, I’ve also noted that the authors are not using the classical definition of the Southern Ocean, (south of 60S), but include mid latitudes of the So Hemisphere also, so my earlier graphs don’t apply to the paper.
Climate Watcher says
The temperature of the tropopause is 220K everywhere e.g. over the poles and over the equator or tropics.
No. http://www.meteo.psu.edu/~nese/3_12_Tropopause_Temperature.bmp
OK I SHOULD HAVE SAID ABOUT 220k (ACTUALLY 210k+/-10). I DO NOT THINK THIS IS SIGNIFICANT. I WAS TRYING TO INDICATE THAT IT VARIED FAR LESS THAN THE EARTH SURFACE TEMPERATURES WHICH CHANGE DRAMATICALLY FROM POLE TO EQUATOR, MONTH TO MONTH AND DAY TO NIGHT.
The thing that is varying is not the CO2 radiation but the radiation at other wavelengths relative to CO2. This radiation will come from the surface and lower troposphere. Clouds will reduce this radiation and so will a very cold surface with high albedo (as in the case of the poles relative to the tropics). In both these cases the radiation characteristic of CO2 will be greater than the background so will appear as a “bump”. There is nothing surprising about this.
Right. Under these circumstances, additional CO2 means more energy is leaving
earth than would otherwise occur.
Incidentally the statement:
“In the Antarctic ( bottom plot ), CO2 presents as a ‘bump’ up in emissions.
CO2 emits to space from the stratosphere at a higher temp than the cold Antarctic
surface, thus INCREASING the loss to space – cooling the Antarctic”
is just wrong.
The tropospause is always colder than the surface although in many places the mountains reach close to the tropopause (which is only at about 8Km at the poles) and so the temperatures will come very close. CO2 is cooling the Antarctic but no more than at any other lattitude.
No. During the Antarctic winter (limited to be sure),
surface temperatures can in fact be lower than the temperatures
at the level of CO2 emission as the spectrum indicates.
THE ADIABATIC LAPSE RATE IS CONSTANT. IT MUST GET COLDER AS YOU GET HIGHER. THE EMISSION SPECTRUM IS SHOWN AS WATTS PER M2. THIS IS TRANSLATED INTO A BLACK BODY TEMPERATURE. HOWEVER THE SURFACE OF THE ICE IS NOT A BLACK BODY. I SUSPECT THIS IS THE REASON FOR THE VERY LOW EFFECTIVE TEMPERATURE. IT CANNOT BE THE REAL TEMPERATURE SINCE IT IS FAR TOO LOW TO BE AN AVERAGE.
Look again at the emission spectra.
http://acmg.seas.harvard.edu/people/faculty/djj/book/bookhwk7-1.gif
Over the Sahara, the dip means a reduction in the energy lost to space due to CO2.
Over the Antarctic, the bump means an increase in the energy lost to space due to CO2.
THE AMOUNT LOST TO SPACE IS THE SAME IN EACH CASE BECAUSE THE EFFECTIVE TEMPERATURE IS THE SAME. YES IT DOES MEAN THAT IT IS LESS OVER THE SAHARA THAN IT WOULD HAVE BEEN IF THERE WERE NO CO2. MY POINT WAS THAT YOU CANNOT POINT TO CO2 COOLING THE ANTARCTIC AS IF IT DID NOT DO SO ELSEWHERE. IF THERE WERE NO CO2 THE ANTARCTIC WOULD ALSO BE COOLER BUT NOT BY AS MUCH AS THE SAHARA.
Increasing the amount of CO2 should increase the width of the dip and the bump
due to band broadening.
The issue that these charts raise is one that I have raised before. The concept of global warming depends on reducing the amount of energy radiated into space by CO2. These charts clearly show that this radiation is being emitted from the coldest layer in the atmosphere. The only way that radiation can be reduced further is for the temperature of this layer to reduce. I am unaware of any good evidence that this is happening.
I believe the average CO2 emissions in the middle of the band are from higher
than the tropopause, from within the stratosphere.
I DO NOT KNOW WHAT YOU MEAN BY “IN THE MIDDLE OF THE BAND”. CERTAINLY CO2 IS THE MAIN COOLANT IN THE MESOSPHERE AND THERMOSPHERE AND IS RADIATING HUGE AMOUNTS OF ENERGY INTO SPACE KEEPING THE THERMOSPHERE TO A RELATIVELY COOL 2000k OR SO!
HOWEVER THIS RADIATION IS COOLING THE STRATOSPHERE AND NOT COOLING THE TROPOSPHERE SO I DO NOT SEE THE RELEVANCE TO THIS DISCUSSION.
And there is evidence in the RAOB data and MSU data of a decades long
cooling trend in strat temperatures as the GCMs do successfully model.
I BELIEVE THE COOLING IS DUE TO THE INCREASED CONCENTRATION OF CO2 IN THE STRATOSPHERE AND NOT DUE TO INCREASED CONCENTRATIONS IN THE TROPOSPHERE, WHICH IS WHAT I UNDERSTAND THE GCMs ASSUME. THIS IS NOT NECESSARILY RELEVANT TO THE TEMPERATURE OF THE TROPOPAUSE SINCE THE TROPOPAUSE IS STILL COOLER THAN THE STRATOSPHERE ABOVE. I AM NOT KNOWLEDGEABLE ABOUT THE THERMODYNAMICS AT THESE LEVELS. I SUSPECT THE CLIMATE MODELLERS ARE NOT EITHER.
But one will notice that much of the trend comes from the resolution of
the El Chichon and Pinatubo eruptions – temperatures rose after the
eruption because of increased absorption by the dust/SO2.
In both cases, after the dust/SO2 settled, temperatures fell to levels much lower than
the pre-eruption levels. What caused this? Not CO2 which steadily increased.
Since Pinatubo resolved circa 1995, there is no significant trend in strat temperatures, though strat temperatures are at a lower temperature than the 1950s.
WHY DO YOU SAY “What caused this? Not CO2 which steadily increased” WHEN INCREASED CO2 SHOULD INDEED LEAD TO LOWER TEMPERATURES?
STRAT TEMPERATURES ARE LARGELY DETERMINED BY INCOMING RADIATION. THE CURRENTLY WEAK SUN MAY BE ALSO BE HAVING SOME EFFECT. HAVING STRUGGLED WITH A FEW PAPERS ON STRATOSPHERIC COOLING I WOULD NOT SUGGEST I UNDERSTAND THE SUBJECT WELL ENOUGH TO DEBATE IT.
That being said, reduction in strat temperature is not the only mechanism of
GHG forcing – band broadening is a significant action as well.
CAN YOU EXPLAIN HOW THE REDUCTION IN STRAT TEMPERATURE BECOMES A GHG FORCING WITHOUT CHANGING THE TEMPERATURE OF THE TROPOPAUSE?
“There isn’t sufficient data in the Antarctic to rely only on the data to do this analysis. We selected two climate models”
So much for the confession-
how about the apology and REFUND THE MONEY?
“The main significance in the AGW debate is that some skeptics use evidence of growing Antarctic sea ice as evidence that there is no AGW. Such an increase in Antarctic sea ice cannot be used as evidence against AGW given the arguments we have put forth.”
So turning that around, diminishing Arctic sea ice cannot be seen as evidence for AGW?
J.Curry
In addition, increased warming will also result in a reduced level of snowfall, but more rain.
Only 2 simple questions .
1) When “will” it happen ? I guess this statement applies to an average (decadal ?) then which decade will be the first one when there will be more rain than snow/hail in Antarctic ? I also guess that the statement implies that once it happens , it will repeat every dacade thereafter .
2) Where “will” it happen ?
As I mentionned I have been to Antarctica (always in summer) . I have seen often precipitations but not once rain . The thermal momentum of the ice mass is so huge that the air temperatures simply can’t get far from 0° even if the wind is blowing from the ocean . When the wind is blowing from the continent I have never ever seen temperatures above 0°C (in summer) .
So if one considers 2 situations where rain is physically impossible :
– over the continent at all season
– over the shore/sea in winter and when the wind is coming from the continent in summer
then where can it rain more than snow in Antarctic ?
In the what-have-you-done-for-me-lately department, I’m taking up some of the complaints raised about this thread (and making a larger observation) in this post:
http://www.collide-a-scape.com/2010/08/18/the-tribal-outcast/
REPLY: Also, I’ve added collide-a-scape.com to the WUWT blogroll, a reciprocal addition would be appreciated. – Anthony
“”” AndyW says:
August 18, 2010 at 12:20 am
Eric Anderson said:
August 16, 2010 at 9:29 pm
“Also, how does snow falling on top of the ocean “stabilize it from the ocean heat below”?”
Reading the paper it makes it less saline so heat is not transferred as much to the more weakly stratified layers. “””
Simply marvellous; the ocean keeps on getting less salty because snow falls in it. How long will we have to wait, until the whole ocean is fresh water so we can solve the world’s drinking water problem ?
And all these years, I have believed that the fresh water on the land; in lakes and rivers, basically comes from the oceans via evaporation and precipitation. So now it appears that the opposite is true; the land supplies fresh water to the clouds, which drop snow over the ocean and gradually turn the whole ocean into fresh water. I suppose that sublimation of ice on Antarctica and Greenland must also contribute fresh water to make the ocean less salty.
It’s totally amazing what you can learn by reading WUWT; that’s WUWT or WUTW or WWUT or UTWW or WUTW……
just in case I spelled it rong.
George E. Smith said
“Simply marvellous; the ocean keeps on getting less salty because snow falls in it. ”
yep, seems logically correct. If you remove it from the macroscale to the microscale then melt ponds in the Arctic also get less saline due to the same thing.
“And all these years, I have believed that the fresh water on the land; in lakes and rivers, basically comes from the oceans via evaporation and precipitation. So now it appears that the opposite is true;”
Yep you learn something new everyday. That’s science, it progresses.
Andy