I’m back after a longer-than-anticipated break from blogging (vacations, field work). If any of you had been following my June blogs (June 2, June 11) on the Daily Herald editorial from last December titled, “Warming theories cooling off,” then here is my long-awaited response to the crux of the article: global climate change is probably not caused by carbon dioxide emissions but by chlorofluorocarbons (CFC’s). According to the Daily Herald article,
The latest research undercuts the whole greenhouse gas theory, a linchpin of the warming hypothesis, even for those who believe in it.
Professor Qing-Bin Lu of the University of Waterloo in Canada has revealed data indicating that changes in global climate may be caused by Chlorofluorocarbons (CFCs) in the atmosphere, not by CO2. These are substances that were once widely used as refrigerants but have been largely phased out since 1978 because of their damage to the ozone layer.
Lu found that CFCs began to decline in the atmosphere around 2000 — just when global temperature also began dropping. According to his findings, this cooling trend could go on for decades.
In my previous blog (June 11) I discounted the editors’ assertion that this article alone was going to bring down the anthropogenic climate change argument, but I hadn’t actually read the article by Quing-Bin Lu. Well, now I have, so I can comment directly about it a bit. (Also, read the comments following that post: some of them mention some of the same points I am about to make.)
Like I expected, I wasn’t able to follow all the technical physics and chemistry in Lu’s article, but I was able to extract a few things. One of the first things I looked for was who funded the research. You can find this information in the acknowledgment section of the paper, which is at the very end. A red flag would be funding by an oil company or a conservative, climate change skeptic “think tank.” In fact, the research was funded by two reputable national agencies of Canada. So far, so good for Lu.
Next, I had to dive into the article. One thing that struck me is that Lu’s central idea—that ozone breaks down in the stratosphere because of interactions with cosmic rays and not because of CFC’s, is equally as hard to swallow as his proposal that CFC’s may be have a bigger control on climate than CO2. Wow! Here is another case where one scientist is attempting to debunk decades of research by hundreds of scientists on how CFC’s destroy ozone. And this vast body of research was the underpinnings of the Monteral Protocol, which is touted by many as being a brilliant example of how world powers can agree to make effective changes to limit their impact on the environment. The Montreal Protocol banned the use of CFC’s by participating countries. Following it CFC emissions dropped and the ozone hole eventually began to be repaired. So it’s quite something for Lu to argue that scientists had that all wrong!
Another thing I noticed is that Lu published this idea that cosmic rays have more to do with reducing stratospheric ozone than CFC’s in 2001, and his article was discounted summarily by another scientist and not picked up on by much of anyone else. In the recent article we are talking about he fights back against the critiques of that scientist, but it seems highly unlikely to me that he is going to gain much more ground this time around. So for climate change skeptics such as the Daily Herald editors to pick up on this article and state that it knocks anthropogenic global climate change dead is delusional. (Thanks Gavin and Eli for your comments RE this on my last post.)
As for climate change being caused by CFC’s, which is really almost a side note in Lu’s article, Lu’s conclusion is not robust. At one point he correlates ozone loss with stratospheric temperature (not ground temperature) in Antarctica to state that there is a strong correlation between ozone loss and climate, but he’s not talking about surface climate, which is what we are all concerned with when discussing global climate change, and correlation between ozone loss at the poles and stratospheric temp at the poles is not an indication of correlation between ozone loss at the poles and surface temp all over the globe.
A few paragraphs later in the article he tries to make the case more directly: he shows that global climate (and this time, I think he really means mean global surface air temperature) correlates well with stratospheric CFC’s, and the correlation looks good, but he doesn’t provide a causal mechanism linking the two. He cites the IPCC as stating that CFC’s are responsible for about 13% of gas-induced anthropogenic warming and argues that, therefore, CFC’s are clearly important. Well, he continues to argue, if they are important, they could be even MORE important! No. Many scientists have studied what they call climate “forcing” by CFC’s and have compared its effect to other gasses, and the conclusion is that CFC’s are responsible for only 13% of the warming that has occurred, not possibly more. Lu’s graph that shows a correlation between CFC’s and global surface air temperature does not prove that it is more. I could graph obesity in the U.S. versus our GDP over several decades and probably get a pretty good correlation, but that doesn’t prove that one caused the other (see also Gavin’s “by-eye correlation” comment on my previous post).
I want to repeat an important point from the previous paragraph: Lu has offered no causal mechanism for why CFC’s would cause more global warming than scientists previously thought. If scientists hadn’t already figured out how important CFC’s are in relation to CO2 and other greenhouse gasses, then such a correlation would effectively be a starting point for further investigation into the effects of CFC’s on global climate. Given that scientists have already figured this out, the recognition of a correlation is going nowhere.
So, once again, I conclude that the editors of the Daily Herald are completely misrepresenting the impact of Lu’s article. They make it sound like it’s the final nail in the anthropogenic climate change coffin, whereas, in fact, the article points out a correlation between CFC’s and climate and speculates (in the face of an already robust body of scientific knowledge) that there might be more there than previously thought. Furthermore, the bulk of the article tries to defend an idea that was proposed nine years ago and that was dismissed the scientific community.
So, we can let Wu go. We won’t hear from him or about him again for a long while, if ever, in regards to climate change science.
What’s more interesting to me now is some mathematical reasoning the editors of the Daily Herald apply further along in their article. Stay tuned—it should be sooner than another couple months before I tackle that.