Lost In The Stratosphere

John Ray has made a few posts, most recently here, arguing that CFC destruction of ozone is, in his words, a “Greenie scare”:

I thought I had covered the ozone story before but cannot see where I did — so: In 1991, the Greenies got everyone to ban CFC chemicals. CFCs were the normal gases that has always been used to make refrigerators and air conditioners work. CFCs even used to put the puff in all our aerosol cans. The ban was because CFCs supposedly destroyed earth’s ozone layer and caused the ozone “hole” over Antarctica. So the hole has of course shrunk by now, right? Wrong! As this U.N. report shows, the hole is as big as ever! Another Greenie scare proved wrong.

Tim Lambert at Deltoid has already demolished most of the assertions in Ray’s first two posts so I will only take on the most recent one. Ray says:

Far from following ANY regular progression, the hole clearly fluctuates wildly — as much as any other natural weather phenomenon

Denying that the ozone hole has followed a progression for the last 20 years falls under the category of “outrageous”. Go here and scroll down to the year-by-year graphic (I can’t link to it directly as it’s actually three graphics). What is immediately apparent from this graphic is that 2002, not 2003, was the anomalous year…

[the ozone hole’s] recent progression from super-small in 2002 to as-big-as-ever in 2003 was predicted by no-one.

…so when I read that assertion from Ray I was pretty sure he’d be totally wrong. It only took me five minutes of looking to find this story from NASA, dated December 2002:

A greater number of large “planetary sized waves” in the atmosphere that move from the lower atmosphere into the upper atmosphere were responsible for the smaller Antarctic ozone hole this fall, according to NASA researchers. The September 2002 ozone hole was half the size it was in 2000…. Newman stressed that the smaller ozone hole this fall is not an indication that the ozone layer is recovering. He said it?s simply due to a change in global weather patterns for this year, and next year it may likely be as large as it was last year.

Ray caps things off with this rather breathtaking statement:

And in science, if you can’t predict it buddy, you don’t understand it. So claiming to have found the “cause” of something you don’t understand is sheer hubris.

Complete rubbish. According to Ray, since I can’t predict exactly where on the Sun the next solar flare will occur (just to pick an example at random), I am disqualified from claiming I understand what causes solar flares. Some phenomena can only be predicted statistically.

Ray has, in three posts, presented nothing to counter the vast bulk of evidence that CFCs do cause ozone depletion – just a truckload of false assertions and the apparent belief that one year’s data is good enough to disprove the whole shebang.

UPDATE: John Ray has responded and asked me to explain “in small words” why the ozone hole has not shrunk despite CFC’s being banned for 12 years. I’ll do my best!

Firstly, CFC’s have not been banned for 12 years. I’m not sure where John got that figure from, but the Montreal Protocol called for a total phase-out of CFC’s by 1995 in developed countries and 2010 in the developing world.

Secondly, CFC’s take about 5 years to reach the stratosphere from time of release. Since many CFC’s are not released at time of manufacture, this actually means some CFC’s can take 15 years to get there.

Thirdly, the CFC ozone destruction process is catalytic, meaning that the ozone-destroying agent is not itself destroyed in the reaction. Chlorine radicals formed from exposure of CFC’s to UV react with ozone, forming chlorine monoxide and oxygen. Oxygen radicals formed by exposure of oxygen to UV then react with the chlorine monoxide forming oxygen and a chlorine radical… which attacks another ozone molecule. The numbers are fuzzy, of course (the range of possible reactions is much more complicated than the brief story above), but in this way it is estimated that one chlorine radical can destroy between 10,000 and 100,000 ozone molecules and remain in the atmosphere up to 75-100 years (eventually precipitating out, usually as HCl). Before you jump on the fuzziness of these numbers let it be said that the strong measures imposed in the Montreal Protocol were a reaction to the observed ozone depletion data, rather than theory. The ozone was being depleted faster than theory back then had suggested.

It’s true that the 2002 shrinkage was not predicted but year-by-year predictions are impossible. Nobody disputes that climate and weather are highly complex systems. The important thing is that the broader trend, of ozone depletion, was predicted and is clearly evident.

Regarding the nuclear testing study, I can’t answer that. My understanding is that certain nitrogen oxides do deplete ozone but that the effect is less important than CFC’s because it is not catalytic and therefore ozone concentration recovers quite quickly. However I have little knowledge of this and no knowledge of the study in question. At any rate nitrogen oxides are a separate issue to CFC’s.

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