Sunday, January 03, 2010

Commander Coincidence

So Eli and Ethon are sitting around wondering whether to turn the snark down for the new year, play nice with the global warming doubters, cut back on the liver snacks, eat fewer carrots, and you know, generally shape up.

On the other hand, Ms. Rabett is out traveling, the beer in the fridge is cold and the supermarkets are open. Hell no, there is too much fun to be had and in the words of the poet

When all about you who have a clue
Are telling you that you missed something
And ignoring what you say
And you are calm and confident
Maybe there's somthin you don't know

Not to peck on the young fellow, but Ethon's new friend Qing Bing (Bunny) Lu should listen. Eli has already had a few words on the subject. Lu's paper in Physics Reports is the toast of the denial-o-sphere,

The cosmic-ray driven electron-induced reaction of halogenated molecules adsorbed on ice surfaces has been proposed as a new mechanism for the formation of the polar ozone hole. Here, experimental findings of dissociative electron transfer reactions of halogenated molecules on ice surfaces in electron-stimulated desorption, electron trapping and femtosecond time-resolved laser spectroscopic measurements are reviewed. It is followed by a review of the evidence from recent satellite observations of this new mechanism for the Antarctic ozone hole, and all other possible physical mechanisms are discussed. Moreover, new observations of the 11-year cyclic variations of both polar ozone loss and stratospheric cooling and the seasonal variations of CFCs and CH4 in the polar stratosphere are presented, and quantitative predictions of the Antarctic ozone hole in the future are given. Finally, new observation of the effects of CFCs and cosmic-ray driven ozone depletion on global climate change is also presented and discussed.
The thing has a history, going back to the late seventies, but really only heating up when QB took a blow torch to the matter, claiming it implied all sorts of crazy stuff and not listening to anyone. This is doubly strange because Lu is at Waterloo and Waterloo has had a bunch of really good molecular chemistry types who wandered into atmospheric science in general and stratopheric ozone in particular. Waterloo is the lead institution for the Atmospheric Chemistry Experiment (ACE) on board the Canadian SciSat, up there measuring the CFCs Lu is babbling about (and Eli is being nice).

Well let's get some preliminaries out of the way. Lu's lab has shown that CFCs are decomposed on ice when low energy electrons attach to them (DEA-dissociative electron attachment). No one is questioning that, but eyes start to cross when he extrapolates the lab measurement to claim that cosmic ray driven DEA is the primary (actually he sometimes appears to say the only) way that CFCs decompose in the atmosphere, with the action taking place on ice particles in the polar stratospheric clouds. In the Physics Reports paper, Lu takes this a step further.
Moreover, this review has also shown that CRE-driven polar O3 loss leads to an 11-year cyclic stratospheric cooling over the past 50 years. The observed data demonstrate that the longterm change of polar stratospheric temperature over Antarctica depends solely on the variation of total ozone, indicating that the effect of greenhouse gases plays a negligible role in the stratospheric cooling over the past five decades. Most strikingly, it is also found that global surface temperature change has an excellent linear dependence on the equivalent effective stratospheric chlorine (EESC). And weak but visible 11-year cyclic oscillations in the surface temperatures are also observed to follow the 11-year CR cycles. These observed data point to the possibility that the global warming observed in the late 20th century was dominantly caused by CFCs, modulated by CRE-driven ozone depletion. With the decreasing emission of CFCs into atmosphere, global cooling may have started since 2002. These observations imply that current climate models may underestimate the effects of CFCs and would have to be revised seriously. This is likely a subject deserving to look at closely.
As Eli said, this thing has a history, folks have been going back and forth with Lu (1, 2, 3, 4, 5) since 2000, pointing out to him, like, yeah, the cosmic ray flux has an 11 year cycle, but so does solar UV intensity. Since the later drives the Chapman cycle (the ozone-oxygen process) as well as photodissociation of CFCs, finding an 11 year cycle in CFC production proves nothing, and simple correlations are not going to do the job, but it is hard to slow Qing Bing down.

The latest, and most complete takedown comes from Rolf Müller and Jens-Uwe Grooß
(open for downloading) in a response to Lu's next to latest. Interestingly, the editors appear not to have accepted a response from Lu, so maybe they thought this was coming to an end.

As Eli said, even without CFC's one is going to find an 11 year cycle for stratospheric ozone driven by the rates of solar ozone formation and destruction and pretty much the same for the ozone hole. To make everyone even happier, El Chichon exploded in 1982 and Pinatubo in 1991, 9 years, not 11 but close enough, especially when you consider that their effects on stratospheric ozone persisted for a few years each. It turns out that both volcanic explosions happened when cosmic ray intensity was rising, and both reduced stratospheric ozone over a period of years. If you account for the stratospheric temperature, halogen loading and the aerosols from the eruptions you get the figure on the right, accounting for the observed ozone loss in the arctic. This does not include the CR-DEA mechanism and for Lu to claim that it is a result of the CR-DEA mechanism he would have to show that one of the other factors was not working. It does not depend on the photolysis rate for the CFCs, only on the observed halogen loading and measured reaction rates. Given what we know about the kinetics of ozone and halogens that is not likely. The last guy who tried that is getting his teeth handed to him in triplicate. Although not explicit in the Physics Reports paper, Lu explicitly relies on the aforementhions Pope ClOOCl absorption cross-section which would limit the amount of ClO in the atmosphere, as a falsification of the photochemical models, but that result is, as they say, in deep doo doo, gone histoire..... (some more to report soon)

CFC concentrations were too small to matter much except in the past thirty years, we only have satellite data on global distributions of ozone since 1978, and the depth and size of the ozone hole depends strongly on stratospheric temperature and the size of the polar vortex, so there is not going to be a huge data series, only two or three 11 year cycles. None of these things is controlled by cosmic rays. Lu's simple eyeball correlation of cosmic ray flux and ozone at the poles over the past 30 years using heavily smoothed data don't prove bupkes because it does not handle any of the confounding factors with anything but a handwave if that.

One differentiates between stratospheric ozone depletion and spring-time polar ozone depletion. The accepted model for stratospheric ozone depletion is that CFCs are emitted at the surface, almost all in the northern hemisphere, and over a period of years diffuse through the tropopause into the stratosphere. The last for a few years in the stratosphere until they rise high enough to be exposed to far UV light which dissociates them. The chlorine atoms, and ClO molecules that are formed catalytically destroy ozone molecules. For more detail google stratospheric ozone depletion, for a lot more detail see the Stratospheric Ozone textbook

Polar ozone holes form in the springtime at first light. During the long months without light at both poles a wind system seals the atmosphere around the poles. Stratospheric clouds of nitric acid trihydride ice particles form in this cold polar vortex. Much of the chlorine in the stratosphere is tied up in ClONO2 and HCl. When these molecules are absorbed on the ice particles, the NO2 is converted to nitric acid, leaving Cl2. Similar things happen to form ClO. The Cl2 is released. Cl2 is very easily photolyzed at sunrise in the spring and you end up with a huge pulse of Cl that chews up the ozone. When the polar vortex disintegrated, NOx and ozone from lower latitudes rushes in, re-establishing ClONO2 and removing active chlorine. The ozone "hole" then fills in. You can find an animation of the process here and, of course, google is your friend.

Lu claims that the major process for destroying the CFCs is dissociative electron attachment on the PSC ice particles where the low energy electrons come from cosmic ray cascades and that it is this process which loads the region inside the polar vortex with chlorine.

Lu's postulated polar DEA mechanism can only occur during the winters. The associated ozone destruction would be a spring time phenomenon driven by cosmic ray intensity. Müller and Grooß looked at the amount of CFC-12 in the antarctic stratosphere between 2004 and 2008 when the cosmic ray intensity was growing. If Lu's theory is correct the amount of CFC-12 should decrease over this period. It does not. Müller and Grooß use ACE data to show this.

Eli has another thought. One of the tells in Lu is that everything is heavily averaged and many of his critics think inappropriately. Without the averaging, most of the claimed correlation goes away. If you think about it, his explanation is a kinetic jump experiment, CFC destruction only occurs in the polar winter (the mechanism for the actual ozone destruction in the polar spring is not any different than the catalytic mechanisms first described by Molina and Rowland what differs is how the free Cl forms). That means that according to Lu the only thing which matters is the cosmic ray flux during the winter, AFTER the polar stratospheric clouds have formed. What Lu needs to do is unsmooth.
Probably more to come.


Martin said...

> Absorbed

Surely you mean 'adsorbed'?

(You guessed it, way over my head, so I'll criticize the language)

Anonymous said...

As a non physicist, I have some difficulty understanding some of the assumptions made to validate the data. Can anyone explain the following:
1) The assumption that since there was no information on EESH against global surface temperatures before 1970, it is safe to assume that a straight line trend from 1980 back to 1970 can be extrapolated back to 1850?
2) It is then safe to use that assumption to talk about the relationship with EESH from 1950, from extrapolated data?
3) I note the comment "Strikingly, it is shown that except the
short-period large fluctuations, the SH, NH and global surface temperatures did not rise
appreciably (within 0.1 oC) from 1850 to 1950". I see no statistics for this confident statement.
It appears to me that Professor Lu sets his own bar for when he uses assumaed data, and for when he gives proper stastical analysis to that information.
I am interested in any mathematical or statistical comments supporting or commenting on this work. It appears to be a house built on sandy foundations to me.