Ralph J. Cicerone

2002 Roger Revelle Medal Winner

University of California, Irvine

Ralph J. Cicerone was awarded the Revelle Medal at the AGU Fall Meeting Honors Ceremony, which was held on 8 December 2002, in San Francisco, California. The medal is given for outstanding accomplishments or contributions toward the understanding of the Earth’s atmospheric processes, including its dynamics, chemistry, and radiation; and toward the role of the atmosphere, atmosphere-ocean coupling, or atmosphere-land coupling in determining the climate, biogeochemical cycles, or other key elements of the climate system.


“It is my honor to present the 2002 Roger Revelle Medalist, Ralph J. Cicerone, Chancellor and Daniel G. Aldrich Professor of Earth System Science at the University of California, Irvine, golf enthusiast, Perry Mason aficionado, would-be announcer for the San Diego Padres, and scientist extraordinaire. Ralph is a rare and special breed: an academician who can move seamlessly from the classroom to the university boardroom, from a discussion of climate models to a television studio discussing an NRC climate change report on PBS’s NewsHour, and from implementing a field experiment on methane emissions in rice paddies to analyzing model simulations of stratospheric ozone depletion. Ralph’s talents are enormous: a keen insight, sharp and quick analytical skills, an unflappable demeanor, and a remarkable ability to retain and recall facts and figures. Equally noteworthy is his passion for science, and his commitment to the application of science to the betterment of the Earth and its inhabitants. The result has been an exceptional body of scientific work that has markedly advanced our understanding of atmospheric chemistry, global biogeochemical cycles, and climate, as well as an extraordinary record of public service that has helped to frame and guide national and international policies on the environment, research and development, and education.

“Ralph’s formal education was in electrical engineering (S.B. from MIT, 1965; Ph.D. from University of Illinois, 1970). He began his research career as an ionospheric physicist at the University of Michigan. However, he quickly got an itch for problems of greater environmental import, and began his self-education in atmospheric chemistry, biogeochemistry, and climate. It did not take Ralph long to hit pay dirt. While trying to assess the impact of rocket exhaust on the stratosphere, Ralph and colleague Rich Stolarski realized that chlorine compounds could catalytically destroy stratospheric ozone. The resulting paper, published in 1974, laid the groundwork for the discovery and quantification of the role of chlorofluorocarbons (CFCs) in stratospheric ozone depletion, and was recognized in the citation for the 1995 Nobel Prize in chemistry awarded to Crutzen, Molina, and Rowland. Ralph’s subsequent work in both the scientific and public policy arenas was pivotal in bringing about the Montreal Protocol and the eventual international ban on CFCs.

“Ralph has been a pioneer in the field of agricultural biogeochemistry. Through novel and carefully executed field experiments, Ralph has quantified the role of gaseous emissions from managed ecosystems in global change, and pro- vided insights into how agricultural practices might be adjusted to minimize emissions from cultivated lands. In the early 1980s, Ralph and colleagues Jim Shetter and C. C. Delwiche undertook the first detailed study of methane emissions from rice paddies and demonstrated that most of the methane released from rice fields comes through the plants themselves. Subsequent work combining flux measurements and isotopic analyses have elucidated the mechanisms that control methane emissions. Ralph’s 1988 review paper with Ron Oremland on methane sources and sinks is the most widely cited paper ever published in Biogeochemical Cycles. More recently, Ralph’s group has contributed important new data on the agricultural emissions of organohalides, suggesting a heretofore neglected linkage between large-scale agriculture and stratospheric ozone depletion.

“Ralph had also made important contributions to our understanding of the causes and possible remedies to human-induced global climate change. During the 1980s, when scientists viewed carbon dioxide as the chief agent for global warming, Ralph, along with Ramanathan, Bob Dickinson, Jeff Kiehl, and Hanwant Singh, first quantified the contributions to global warming made by non-CO2 greenhouse gases, such as methane, nitrous oxide, and upper tropospheric ozone. Their report, indicating that non-CO2 gases effectively double the greenhouse radiative forcing, profoundly influenced scientific thought and research on climate change, and suggested the possible viability of alternate strategies for slowing global warming.

“A scientific leader and a leader among scientists, Ralph has been elected to the National Academy of Sciences, the American Philosophical Society, and the Academy of Arts and Sciences and is a past president of the American Geophysical Union. He has received the AGU Macelwane Medal, the United Nations Environment Program Ozone Award, and the Bower Award and Prize for Scientific Achievement. Today, for his extraordinary breadth of contributions to the understanding of biogeochemical cycles and their effect on climate, Ralph Cicerone is most deservedly receiving the 2002 Roger Revelle Medal.”

—WILLIAM L. CHAMEIDES, Georgia Institute of Technology


“President Dickinson, officers and members of the AGU, and honored guests, I am very honored and happy to receive this medal because it is in the name of the great Roger Revelle and because the selection was made by AGU colleagues. Thank you for that very generous citation, Bill Chameides. If you in the audience think that he looks young now, you should have seen him in 1973 when he arrived as a postdoctoral researcher to work with Rich Stolarski and me!

“Very few people have colleagues as good as I have had and also have now. They have made the journey toward research results enjoyable, meaningful, and educational. They include Rich Stolarski, Shaw Liu, Bill Chameides, Jim Russell, Paul Crutzen, Ray Weiss, the Shetter brothers, the late Connie Delwiche, Ramanathan, Bob Dickinson, Guy Brasseur, Ron Oremland, and a great group of colleagues and students at the University of California, Irvine, along with Japanese, European, and South American scientists. I have learned from each of them and continue to do so. One good example was when Rich Stolarski and I wrote our first paper on ozone destruction by chlorine and it was rejected by a prominent journal (not in AGU’s stable) whose reviewer said that the idea was ‘of no conceivable geophysical consequence.’ Rich said not to worry, because we would have a lot of other good ideas in our careers.

“AGU has been a wonderful scientific society for me. When a couple of us wanted to convene the first sessions on atmospheric chemistry, AGU was the only society that encouraged it. With some work, these special sessions came to be replaced by regular sessions, the field expanded, AGU created a new section of JGR, and the membership of the Atmospheric Science, Hydrology, and Oceanography sections grew as climate science became more important. Global Biogeochemical Cycles was created, and now there is a new section: Biogeosciences. For all of this, we thank our AGU colleagues in the solid Earth and space sciences for their scientific broad-mindedness. My guess is that Roger Revelle would have welcomed all of this.

“While I may be lucky to have such good colleagues, all of us are fortunate to have support for our research in this country—from the National Science Foundation and NASA in my case. The Joan Irvine Smith/Athalie Clarke Foundation and the Keck Foundation have also been great supporters. Their resources have allowed us to study the Earth, to explore and to quantify the behavior of the ozone layer, the sources of gases that comprise the air and that lead to human-caused radiative forcing of the climate, and now to the impacts of human activities like fossil-fuel burning and agriculture. We are privileged to be able to participate in such research with such colleagues. And I have had the best partner through it all: Professor Carol Cicerone.”

—RALPH J. CICERONE, University of California, Irvine