Scientist Honored for Role in Landmark Discovery of CFC Damage to Ozone Layer

F. Sherwood Rowland, along with colleagues Paul Crutzen and Mario Molina, was awarded the Nobel prize last November for discovering the threat chlorofluorocarbons pose to the ozone layer, for working to preserve the ozone layer, and for protecting human welfare. In May 1995 AGU awarded one of its highest honors, the Roger Revelle medal, to Rowland for his role in this work. The following remarks are excerpted from a speech by Richard P. Turco of the University of California, Los Angeles, who presented the AGU award.

Sherwood (Sherry) Rowland is perhaps the ideal candidate for the Revelle Medal of the American Geophysical Union. I can think of no one in the field of atmospheric sciences better suited to receive this high honor, named for an intrepid crusader on behalf of the environment, the late Roger Revelle. I have known Sherry since 1975, which was soon after the publication of his landmark paper with Mario Molina on the depletion of stratospheric ozone by chlorofluorocarbons (CFCs). That brilliant piece of deductive science stands as the major triumph of the physical sciences in building a case for acting to preserve the global environment. It is the only theory of "global change" that has been universally accepted, and it now stands as a shining paradigm for international responsibility to safeguard the environment.

"Sherry not only proposed, with Molina, the original theory of chlorofluorocarbon erosion of the ozone layer, he has relentlessly pursued the science and policy implications of ozone depletion. Although hundreds of researchers have contributed in important ways to the scientific evolution of the problem, Sherry has been the major figure in bringing the issue to prominence and seeing it through to resolution under the Montreal Protocol. Roger Revelle himself would have acted as forcefully and singlemindedly in such a good cause. "Sherry was a graduate student at the University of Chicago during that heady time following the Manhattan Project and the end of World War II when physicists and chemists figured they knew everything, or at least could control everything. Sherry worked with Willard Libby and became involved in radiochemistry, using radionuclides to trace the sources and sinks of materials. It is therefore no coincidence that Sherry developed an instinct for determining the behavior and lifetimes of chemical compounds in the environment. That instinct eventually led him to think about chlorofluorocarbons, which have no significant natural sources and no obvious sinks. Ironically, his realization that the main loss of chlorofluorocarbons must involve stratospheric decomposition leading to ozone depletion eventually proved that natural systems, even on global scales, are not always resilient to anthropogenic stress and must be protected accordingly. "Sherry's scientific output has been astounding. His listing of 312 papers and articles is a sign of extraordinary fruitfulness. A number of Sherry's papers on chlorine chemistry and ozone depletion are classics. In other work, he helped to resolve the origin of the "ozone hole"—a deep reduction in the ozone layer over Antarctica discovered in the early 1980s—by suggesting that CFC photochemistry in the presence of particles was the cause. In 1986, a novel analysis of ground-based ozone observations with his graduate student, Neil Harris, first revealed alarming decreases in ozone abundances over the northern hemisphere in certain seasons. Again, these decreases have been linked with CFCs. "It is not possible to exaggerate the continuing importance of Sherry's basic research for underpinning the theory of ozone depletion by chlorofluorocarbons and other compounds. Sherry's efforts in the laboratory, field, and lecture halls around the world have led directly to the Montreal Protocol, the banning of CFCs, and, in the bargain, the likely easing of greenhouse warming. In addition to these seminal discoveries concerning the depletion of ozone by CFCs, Sherry has been a leader in measurements of atmospheric methane and other hydrocarbons. Methane is a key greenhouse-active gas, it participates in stratospheric and tropospheric chemistry, and it controls the amount of water vapor in the upper atmosphere. Sherry's work defined, with clarity and accuracy, an increase in methane over the last decade that is very likely associated with human activities. "Sherry has won countless awards and honors for his research contributions and for professional activities and community service. Sherry is a member of the National Academy of Sciences and is soon to be its Foreign Secretary. He is a Fellow of the American Geophysical Union, the American Physical Society, and the American Association for the Advancement of Science. Sherry holds six honorary doctorates. Among the most important awards he has garnered are the Tyler World Prize for Environmental Achievement (1983) and the Japan Prize in Environmental Science and Technology (1989). Those were the most important awards until today, when he officially receives the medal named in honor of another environmental hero and role model, Roger Revelle, who would be most happy to see Sherry wearing the medal named after him."

Source: Eos, Dec. 26, 1995, p.535.

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