Sherwood Rowland, CFCs, ozone depletion and the public role of scientists

Sherwood Rowland, CFCs, ozone depletion and the public role of scientists

Many of you will have read the obituaries of the Nobel Prize-winning chemist Sherwood Rowland (Nature, BBC) who sadly died over the weekend. DotEarth has a good collection of links to papers, videos and tributes.

We have sometimes commented on the connections between the issue of CFC-driven ozone depletion and anthropogenic global warming. In both cases, there is a global atmospheric problem caused by specific emissions, that has a potential to be dangerous, for which the science provided strong evidence for (but never absolute proof), and for which observations ran ahead of predictions for many years. In the ozone case, this led to important preventative actions (via the Montreal Protocol and its amendments). There are of course links that go deeper than just analogies – ozone depletion itself has a small cooling effect, CFCs are important greenhouse gases, and prior to the Montreal protocol amendments, were a large component of the year on year increase in radiative forcing. Indeed, the Montreal Protocol has done more to reduce radiative forcing than any other climate mitigation measure – and it isn’t even a climate mitigation measure!

Going the other way, ozone depletion is a chemical process and is affected by temperatures and water vapour in the stratosphere. Ozone recovery in the tropical stratosphere is expected to be faster and the recovery of the polar ozone hole is expected to be slower because of the CO2-induced cooling of the stratosphere (and increase the number of polar stratospheric clouds). Another link is associated with the dynamical impact of the ozone hole around Antarctica increasing the westerly winds dramatically.

There are also links that are perceived in the broader public that are not actually true: CFCs are not aerosols (despite what the New York Times claims), global warming does not exist because of extra heat coming in through the ozone hole, and aerosol sprays do not cause global warming.

In the public debate, many of the climate contrarians (such as Fred Singer) got their start denying that CFCs were affecting ozone, using many of the same arguments they now use about climate change (CFCs are heavier than air! it’s all the sun! the science is uncertain! the scientists are KGB agents! any controls will cause untold misery in the developing world!), and for much the same reasons. But through this all, Sherry Rowland strode tall (literally – he was 6 ft 5 in), and played a large role in debunking some of the wild claims (such as the idea that it was all volcanoes).

Several of us at RealClimate had the honor of getting to know Sherry during the latter years of his career. And those of us who did know him can attest to the fact that he was not only a great scientist, but a great person, who displayed remarkable kindness and generosity. This is perhaps best demonstrated by a personal anecdote. One of us (Mike) got to spend some time with Sherry during a visit to the University of California-Irvine a few years back. The topic of Mike’s lecture was human-caused climate change, and at the end of the talk, one member of the audience – a local who had decided to attend the seminar – made a comment during the Q+A casting doubt on the greenhouse effect, suggesting that CO2, because it was heavier than other air molecules, would simply sink to the ground (a myth that is encountered surprisingly often). Mike pointed out to the questioner the obvious things–that the atmosphere is well-mixed, etc. and so the atmosphere does not stratify according to molecular weights of its constituents, and indicated that he’d be happy to discuss this with him further after the formal part of the lecture. At the reception after the lecture, Sherry could not immediately be found. While everyone else was enjoying a beverage, cookies, and conversation, Sherry had been off in the corner for about 30 minutes talking with the questioner, explaining basic principles of atmospheric science, how the greenhouse effect works, etc. It didn’t matter that one of the two of them had a Nobel Prize while the other may not have had any formal education. What mattered to Sherry is that he had an opportunity to educate someone about this important issue, and that mattered more than anything. It was an inspirational moment–likely one of many inspirational moments experiences by those who were fortunate enough to spend any time around him.

Sherry was deeply involved in advocating for policy restrictions on ozone-depleting substances, and made some very profound comments on the role of science in policy. Most notably, in his acceptance speech for the Nobel prize he said:

“What’s the use of having developed a science well enough to make predictions if, in the end, all we’re willing to do is stand around and wait for them to come true?”

That is a line that continues to inspire new generations of scientists. He will be missed.


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