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Discovering the End of the World

The recent death of Sherwood Rowland, whose work helped us avoid one of the world’s great environmental disasters, should be a reminder that we can’t afford to ignore the lessons of chemistry.
March 15, 2012

The work and life of F. Sherwood Rowland, a chemist at the University of California, Irvine, who died last weekend, should provide ample inspiration for those now grappling with the debate over climate change. 

F. Sherwood Rowland. Credit: UCI Libraries’ Special Collections & Archives.

Rowland is best known for figuring out, along with his then post-doc Mario Molina, in the early 1970s how chlorofluorcarbons (CFCs), industrial chemicals widely used in, among things, air conditioners and aerosol sprays, were destroying the protective atmospheric ozone layer. (Rowland, Molina, and Paul Crutzen of the Max Planck Institute shared the 1995 Nobel prize in chemistry for the work.) Rowland also did pioneering work in other areas involving the monitoring and chemistry of trace gases, including research on the rise of methane in the atmosphere. But perhaps his greatest achievement was his demonstration that seemingly simple chemical reactions could play out over a massive scale and have planet-wide effects.

As I wrote in a 2007 Review on the 20th anniversary of the Montreal Protocol, an international treaty that effectively phased out the use of CFCs, Rowland helped to change our fundamental understanding of atmospheric chemistry:

Until the early 1970s, it could be said that, like politics, all chemistry was local. That changed in dramatic fashion with a series of discoveries concerning the global effects of a family of chemicals called chlorofluorocarbons, or CFCs…

The researchers found that the CFCs wafted up through the lower atmosphere intact, too stable to react with the swirling brew of chemicals around them. But once they reached the mid-­stratosphere, above most of the protective layer of ozone, the intense solar radiation broke the CFC molecules apart, releasing chlorine. Two simple reactions gave Rowland and Molina concern: Cl + O3 = ClO + O2, and ClO + O = Cl + O2. That is, chlorine (Cl) reacted with ozone (O3), generating chlorine monoxide (ClO), which in turn reacted with an oxygen atom to release another chlorine; the net result was that the chlorine was destroying ozone without depleting itself. “When we found the chain reactions” occurring in the ozone layer, remembered Rowland this fall, the fate of CFCs “suddenly went from a scientific curiosity to an environmental worry.”

Rowland loved to tell a story about his discovery. When his wife asked him how his work was going, he answered, “well, it is going very well—except it looks like it might be the end of the world.” It is a funny story, but it is also one that gets at a profound insight:  increasing our understanding of chemistry is a great achievement, but we better be prepared to abide by what the science tells us.

It took more than a decade for Rowland to convince the world—and most notably the chemical industry—that his insight into the chemistry was correct. Though the United States banned the use of CFCS in spray-can applications in 1978, the chemicals remained a mainstay of refrigeration until the finding of an “ozone hole” above the Antarctic prompted the passage of the Montreal Protocol.

Controlling emissions of greenhouse gases and understanding the complexities of climate change will, no doubt, be more complex and expensive that it was to address the impact of CFCs on the ozone layer. But Rowland’s tireless faith in advocating for policies based on the science needs to be remembered. For years he was aggressively challenged, particularly by those in the chemical industry. The idea that inert chemicals released by a spray can, could, somehow, have global effects on the atmosphere was ridiculed. Then, finally faced with the overwhelming evidence of the damage that CFCs were doing, companies found new chemicals to replace CFCs and began racing to build production capacity of the alternatives. Almost overnight, it seemed, the industry began embracing the lucrative business opportunities possible in replacing chlorofluorocarbons. As is almost inevitably the case, the science had won out. 

I recall in the late 1980s hoping to interview Rowland at an American Chemical Society meeting. By then, he was already one of the world best known chemists. But for hours, as I waited impatiently, he sat in the front row of the dingy conference room, listening to endless presentations by young researchers on their latest findings. His interest never seemed to wane, despite the seemingly endless talks and slides showing the latest results of ongoing experiments. His message was clear to everyone in the room: understanding the minute details of chemistry matters.

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