If you got a hammer

Steve Bloom brings word of the latest Einstein, better than Chilingar, more powerful than Gerlich and Tscheuschner, able to leap high hockey sticks in a single bound, with the newest version of global warming is caused by cosmic rays.

There are two parts to this story, the first is an interesting idea that low energy electrons can dissociate CFCs in ice matricies. This idea has, as such things go, a relatively long provenance, going back to the 1980s and enjoying a revival in the recently deceased Ted Madey's lab at Rutgers at the end of the last century (well, 10-12 years or so). The idea has been aggressively pursued by one of Madey's students Qing Bin Lu at Waterloo, whence comes the latest, to be published in Physics Reports as a "review". To be honest (and Eli is ever so), the first part of the paper is a good summary of the past laboratory work, but the second half on climate science, descends into hammer territory, as in when you have a hammer, everything looks like a nail, something that folk who work in on a single system are subject to. The editor for the paper, Sigrid Peyerimhoff, a really good theoretical chemist, had done very early calculations on the mechanism championed by Lu. FWIW Eli also knows some chemists and atmospheric scientists at Waterloo and thinks highly of them.

The idea, which has been kicking around for about as long a time is that CFCs are not dissociated by UV sunlight, mostly in the stratosphere in the tropics, where the light is most intense, but at the poles, in the polar stratospheric clouds, by low energy electrons formed in cosmic ray cascades. This was published by Lu in Physical Review Letters early in the decade and got not one, but two comments, and a more recent PRL publication, the latter being out from under the paywall.

Lu says that there is a strong anticorrelation between cosmic ray flux and ozone at the poles where Polar Stratospheric Clouds form (or in other words, more cosmic rays, less ozone). He puts forth, what with charity could be called a simplistic model, called the cosmic ray driven electron reaction model, which is nothing more than a correlation of the ozone change against the cosmic ray flux, with its 11 year cycle. There is nothing more than a simple least square fit and even that is minimal, and the lines are thick, the scatter of measurements wide. There is no kinetic model beyond the naive fit, and there is no discussion beyond, lookatthat quantifying the fit.


The CRE "model" is just

[O₃]_i = [O₃] _o {1-k I_i I_i-1 EESC_i ]

where [O₃]_i is the ozone column depth in year i, [O₃] _o would be the column depth without CFCs, I_i is the cosmic ray flux in year i, and EESC_i is the equivalent effective stratospheric chlorine over Antarctica. k is a fitting constant.

As was pointed out in one of the PRL comments, the correlation only looks reasonable for the latest cycle, and the scatter is so large that without the running average it would disappear there. The bunnies can get another view of this by looking at the 1990 to 2008 ozone variability vs variability in the cosmic ray flux.




Before going on, Lu does provide a prediction

The intensity of cosmic rays is still peaking in 2009, so we should expect to observe one of the deepest ozone holes over the spring Antarctica in 2009~2010.

and as it turned out we didn't. There are two measures of an ozone hole, the area, and the minimum ozone column density. 2009 was a middling hole for recent conditions, the hole was smaller than in any year since 1996 except 2002 and 2004, the ozone column was middling for the same period.

This should not be surprising, Lu himself shows that there is a much better correlation between temperature and ozone, as the photochemical model implies than his CRE model, but not to be daunted, Lu next claims that the temperature is controlled by the cosmic rays.

Much hand waving ensues, during which claims are made that because cosmic rays control the ozone at the poles, and ozone depletion at the poles contributes to ozone depletion at mid latitudes, ozone depletion controls global temperature. Something like that.

Tamino is going to feast on this one.