From the AGU Weekly Journal Highlights
While sea ice extent has declined dramatically in the Arctic in recent years, it has increased slightly in the Antarctic. Some scientists have suggested that increased Antarctic sea ice extent can be explained by the ozone hole over Antarctica. Previous simulations have indicated that the ozone hole induces a large change in atmospheric circulation in austral summer and that this change in circulation could contribute to the changing Antarctic sea extent.
To learn more, Sigmond and Fyfe use a climate model, forced by monthly varying observed stratospheric ozone changes from 1979 to 2005, to simulate the effects of stratospheric ozone depletion on Antarctic sea ice extent.
Contrary to predictions of previous studies, their model finds that ozone depletion would lead to a year-round decrease in Antarctic sea ice extent rather than the increase that was observed. The results suggest that processes other than ozone depletion must be causing the observed increase in Antarctic sea ice extent. It remains unclear why Southern Hemisphere sea ice trends differ so greatly from Northern Hemisphere trends.
Title: Has the ozone hole contributed to increased Antarctic sea ice extent?
Authors: M. Sigmond: Department of Physics, University of Toronto, Toronto, Ontario, Canada;
J. C. Fyfe: Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, British Columbia, Canada.
Source: Geophysical Research Letters, doi:10.1029/2010GL044301, 2010 http://dx.doi.org/10.1029/2010GL044301
GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L18502, 5 PP., 2010
doi:10.1029/2010GL044301
Has the ozone hole contributed to increased Antarctic sea ice extent?
M. Sigmond
Department of Physics, University of Toronto, Toronto, Ontario, Canada
J. C. Fyfe
Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, British Columbia, Canada
Abstract:
Since the 1970s sea ice extent has decreased dramatically in the Northern Hemisphere and increased slightly in the Southern Hemisphere, a difference that is potentially explained by ozone depletion in the Southern Hemisphere stratosphere. In this study we consider the impact of stratospheric ozone depletion on Antarctic sea ice extent using a climate model forced with observed stratospheric ozone depletion from 1979 to 2005. Contrary to expectations, our model simulates a year-round decrease in Antarctic sea ice due to stratospheric ozone depletion. The largest percentage sea ice decrease in our model occurs in the austral summer near the coast of Antarctica, due to a mechanism involving offshore Ekman sea ice transport. The largest absolute decrease is simulated in the austral winter away from the coast of Antarctica, in response to an ocean warming that is consistent with a poleward shift of the large-scale pattern of sea surface temperature. Our model results strongly suggest that processes not linked to stratospheric ozone depletion must be invoked to explain the observed increase in Antarctic sea ice extent.
Received 11 June 2010; accepted 5 August 2010; published 29 September 2010.
Citation: Sigmond, M., and J. C. Fyfe (2010), Has the ozone hole contributed to increased Antarctic sea ice extent?, Geophys. Res. Lett., 37, L18502, doi:10.1029/2010GL044301.
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Related reading:
Galactic Cosmic Rays May Be Responsible For The Antarctic Ozone Hole
AJB says October 6, 2010 at 9:35 am
I think I must have this arse backwards! NLCs have decreased of late, presumably because increased UV is breaking down more water vapour into OH + H2. How does this affect the ozone breakdown and why the lag? Anyone out there with the latest thinking on this stuff who can straighten this out?
Stephen Wilde says:
October 6, 2010 at 8:33 am
You are absolutely right, but you are not “a la mode liberal”, then you are a “bad kid” 🙂
>>Tom_R Do you have a reference?
Phil. October 6, 2010 at 9:58 am : Yes CFC and their photolysis products have been measured, first by Lovelock in the 70s as I recall. <> Phil. October 6, 2010 at 9:58 am : The percentage that does make it is way to small too have a major effect, nobody is “assum(ing) that chlorine released from CFC-12 is a significant source compared to chlorine released from NaCl”, it’s been measured (many times), fluorine containing products are a key marker. <<
For fluorine, the concentrations are less that half those for chlorine. That says to me that natural chlorine accounts for more than half the stratospheric ozone depletion effect, even assuming no natural souce for fluorine. If there is a natural source of the stratospheric fluorine, then CFC-12 is even less of a source.
http://www.springerlink.com/content/l4741h238x50q677/
Also, the discussions of oceanic chlorine only consider HCl, but there is a significant amount of sodium in the stratosphere.
http://www.pnas.org/content/79/8/2737.full.pdf
"The presence of significant amounts of sodium in the upper
atmosphere has been known since 1938, with the identification
of the yellow radiation of the twilight air glow as the 589.3-nm
emission from excited Na(2P) atoms (1, 2)."
AJB says:
October 6, 2010 at 10:13 am
AJB says October 6, 2010 at 9:35 am
I think I must have this arse backwards! NLCs have decreased of late, presumably because increased UV is breaking down more water vapour into OH + H2. How does this affect the ozone breakdown and why the lag? Anyone out there with the latest thinking on this stuff who can straighten this out?
Those mesospheric clouds are above the ozone formation region, it’s stratospheric clouds that affect the ozone layer. If the mesosphere H2O concentration goes up then you might see increased NLC even with increased UV. As I recall stratospheric H2O has been going up.
Tom_R says:
October 6, 2010 at 12:49 pm
>>Tom_R Do you have a reference?
Phil. October 6, 2010 at 9:58 am : Yes CFC and their photolysis products have been measured, first by Lovelock in the 70s as I recall. Phil. October 6, 2010 at 9:58 am : The percentage that does make it is way to small too have a major effect, nobody is “assum(ing) that chlorine released from CFC-12 is a significant source compared to chlorine released from NaCl”, it’s been measured (many times), fluorine containing products are a key marker. <<
For fluorine, the concentrations are less that half those for chlorine. That says to me that natural chlorine accounts for more than half the stratospheric ozone depletion effect, even assuming no natural souce for fluorine. If there is a natural source of the stratospheric fluorine, then CFC-12 is even less of a source.
You asked me for a source, I gave it you, perhaps you will now do the courtesy of reading it before posting your erroneous theories?
Phil. says October 6, 2010 at 1:06 pm
As I recall stratospheric H2O has been going up.
Thanks Phil, any links on this? The intriguing bit for me is how this varying amount of water gets up to the mesopause and forms ice – in what form and what state changes are involved? Is this just nucleation and liquid water freezing or in fact an OH + H2 reaction and direct deposition? We’re at the very top of the homoshpere here, the reported time lag and lattice structures are all a bit odd.
While minor amounts of H20, NLCs seem to be an indicator of sorts that tell us change is underway but as yet not how or why. Wikipedia has a reasonable article about them but I’m not sure how sound or up to date some this is:
http://en.wikipedia.org/wiki/Noctilucent_clouds.
The whole topic seems to have gone off the radar of late for ordinary Joes like me outside the climate field. I guess we’ll hear more from the AIMS mission as time passes.
AJB says:
October 6, 2010 at 5:14 pm
Phil. says October 6, 2010 at 1:06 pm
As I recall stratospheric H2O has been going up.
Thanks Phil, any links on this? The intriguing bit for me is how this varying amount of water gets up to the mesopause and forms ice – in what form and what state changes are involved? Is this just nucleation and liquid water freezing or in fact an OH + H2 reaction and direct deposition? We’re at the very top of the homoshpere here, the reported time lag and lattice structures are all a bit odd.
While minor amounts of H20, NLCs seem to be an indicator of sorts that tell us change is underway but as yet not how or why. Wikipedia has a reasonable article about them but I’m not sure how sound or up to date some this is:
I’ll see what I can find, I recall a paper discussing increased methane concentration in the stratosphere and above leading to increased water and also increased ‘leaking’ through the tropical tropopause (from storms?).
That Wiki article looks very good, well referenced.
So the Ozone hole doesn’t appear to be the reason for the lack of retreat in Antarctic sea ice. I don’t see that as remarkable.
According to this link from NASA, stratification of fresh water at the surface inhibiting heat transfer from the lower ocean is an important factor. They also point out that increased precipitation (snow) will result in thicker ice.
http://www.nasa.gov/topics/earth/features/antarctic_melting.html
Phil. says October 7, 2010 at 5:34 am
A paper that may shed some light on this aspect (Ref 4 in the Wiki Article):
Murray, B.J., E.J. Jensen
Homogeneous nucleation of amorphous solid water particles in the upper mesosphere
Journal of Atmospheric and Solar-Terrestrial Physics, 72, 51-61 doi:10.1016/j.jastp.2009.10.007, 2010.
Abstract:
Unfortunately it’s behind a pay-wall so $$$ for me but I’m guessing not for you :-). Dr Murray’s group at Leeds Uni seem to be doing lots of other interesting stuff that may whet your appetite: http://www.chem.leeds.ac.uk/BJM/publications.htm. Such a shame most of it isn’t publically accessible!
What a strange place to hide this … (scroll to bottom of page):
http://www.chem.leeds.ac.uk/BJM/Interests.htm
See also these pages:
http://www.chem.leeds.ac.uk/JMCP/ice.html
http://www.chem.leeds.ac.uk/JMCP/meteor_meso.html
Curiouser and curiouser … a lot going on up there and these guys seem to be nailing it bit by bit. Cracking stuff guys, but come out from behind those damned pay-walls please! Think about it – who’s ultimately funding you?
Ok let me see if I have this straight :
Melting ice – blame CO2
Growing ice – blame ozone
Got it.
I seem to recall one environmentalist saying he first became aware of how sensitive the environment was to human contamination after learning that the simple use of spray-can CFC’s had caused a huge hole to open up in the protective ozone layer over the Antarctic.
As that hole is still there and apparently as large as ever, decades after the general ban on CFC use, perhaps that hole was a natural feature of the atmosphere that had just been discovered.
@Spector –
I am with you on that. I said at the time – literally – that it quite easily could have been a naturally occurring event, most likely due to the electromagnetic peculiarities of the magnetic pole. And I DID predict that even after we stopped using CFCs the hole would still be there, as big and bad as ever.
But I also knew that they would say, “See? We told you the CFCs would have a long-term effect!”
The thing about it was that the hole in the ozone issue was the run-up to global warming, although none of us on the outside had any idea at the time. That one was so successful – and so FAST – that it encouraged them.
The earlier scare – acid rain – fell off the map after the federal gov’t put up $35M to actually go out and find empirical evidence. They even let the greens go out and collect the samples themselves. And what did the study prove? Only one or two small ponds in upstate New York – out of all the tens and tens of thousands of ponds and lakes in the U.S. had gone acidic at all (and there was no reason to think that those two, and only those two, had been caused by emissions. The result? The acid rain scare died a sudden death.
But the greens learned a lesson: Don’t make claims that can be falsified.
Ergo, a hole in the ozone – over the South Pole. No one except “them” (scientists) can go get samples. (I know someone who DID demand – and get – a sample of acid rain in a lake in NE Illinois.)
Ergo, CO2 emissions causing a long-term devastating warming of the climate. It is no accident that they put the danger over 100 years into the future, where no one could go to see that it did or did not happen. (And everyone in 1990 who was claiming global warming would be long since dead and unavailable for castigation.)
So, they had two trials – one fell flat on its face and the other was a screaming PR and policy success. By the end of the 1980s they were ready to push the envelope.