Susan Solomon

2007 William Bowie Medal Winner

National Center for Atmospheric Research

Susan Solomon was awarded the 2007 William Bowie Medal at the AGU Fall Meeting Honors Ceremony, which was held on 12 December 2007 in San Francisco, Calif. The medal is for “outstanding contributions to fundamental geophysics and for unselfish cooperation in research.”


I am particularly pleased tonight to present Susan Solomon, who will receive one of the most prestigious AGU awards: the William Bowie Medal.

As early as the late 1970s, Susan was preparing her Ph.D. thesis at National Center for Atmospheric Research under the scientific supervision of Paul Crutzen and Harold Johnston. Susan became fascinated by the mechanisms that affect ozone and other chemical compounds in the upper atmosphere. She assessed the vulnerability of upper atmosphere ozone to energetic particles of solar origin, and showed how thermospheric perturbations associated with solar activity could propagate down to the middle and even the lower polar atmosphere. When the springtime Antarctic ozone hole was reported in 1984, Susan realized that no known mechanism could explain this dramatic and unpredicted perturbation. She provided a possible explanation: Chlorine atoms originating from the industrially manufactured chlorofluorocarbons, if activated on the surface of ice particles present in polar regions, could destroy most of the lower stratospheric ozone in only a few weeks. This theory was challenged. Atmospheric dynamicists had suggested that changes in the atmospheric circulation were a more likely cause for this observed ozone depletion, while several chemists were invoking the role of the nitrogen oxides produced during high solar activity periods. The solution came a few years later, after the completion of an Antarctic expedition led by Susan: Chlorine was the culprit. Its concentration was indeed elevated in regions where polar stratospheric clouds were present, and ozone was depleted in just a few weeks. Susan provided the leadership to the first measurements showing that halocarbons are the cause of the ozone hole. This discovery played a decisive role in the decision made by the nations of the world to ban the use of chlorofluorocarbons. This year, we celebrated the twentieth anniversary of the Montreal Protocol for the protection of the ozone layer.clouds, and marine boundary layers.

The climate issue is today on the agenda of many nations of the world, but many complex questions remain to be addressed. Susan decided to elucidate the influence of the stratosphere in the climate system, and focused on the effects of ozone and halocarbons on climate.

Susan Solomon soon understood the need to communicate important scientific results to decision-makers and more generally to the public. She decided to contribute to several international environmental assessments and, with many of her colleagues, became instrumental in providing the scientific basis that lies at the foundation for decisions by society. In the past 5 years, she served as the cochair of the Intergovernmental Panel on Climate Change (IPCC) Working Group I. This IPCC report, published in 2007, made headlines and paved the way for actions on climate change. The effort, which took more than 3 years of intense activity and involved scientists from more than a hundred countries, had a major influence on the political agenda that will ultimately lead to mitigation and adaptation measures needed to protect humanity from adverse climate change. Recently, the Norwegian Nobel Committee awarded the 2007 Nobel Peace Prize to former Vice President Al Gore and the IPCC.

Finally, I would like to highlight the important educational role played by Susan Solomon. In addition to her scientific activities, Susan contributed immensely to informing the public on climate change and ozone depletion. She entrained a new generation of scientists who realize the fragility of our planet and, through her enthusiasm and mentoring skills, has fostered the careers of many young researchers.

—GUY BRASSEUR, National Center for Atmospheric Research, Boulder, Colo.


It’s an overwhelming joy to receive the Bowie Medal, because it comes from one of our field’s key professional societies. It just doesn’t get any better than this kind of recognition from your peers.

I would like to briefly sketch how privileged I’ve been both in terms of what I’ve been able to study, and with whom I’ve been lucky enough to work. The discovery of the Antarctic ozone hole by a group of scientists at the British Antarctic Survey sent shock waves around the world a bit more than two decades ago. I had the honor of collaborating with Rolando Garcia in suggesting that reactions involving hydrochloric acid from chlorofluorocarbons on cloud surfaces might be the cause of the mysterious hole; that idea is now well recognized as correct. I was also blessed to have Ryan Sanders as primary collaborator in taking the first data directly implicating this unusual chemistry. Working beside A. R. Ravishankara and colleagues, I benefited hugely from their powerful insights from the laboratory. Most recently, I’ve had the great luck to work with Dave Thompson in showing how ozone depletion affects the surface climate of Antarctica as well as the distribution of stratospheric temperatures. I’ve also enjoyed wonderful collaborations with students and other members of my research group, who helped and inspired me.

I take heart in the belief that the ozone hole and climate change have demonstrated that the planet and its resources are vast but finite, and I’m optimistic that society can make good decisions when armed with good scientific information. I’ve devoted a substantial amount of my time to scientific assessments of ozone depletion and climate change, to bring the best possible information to the public and to policymakers. In doing so I have followed the incomparable traditions of ozone and climate science assessments provided by the founding wisdom of Dan Albritton, Bob Watson, Sir John Houghton, and Bert Bolin.

In co-chairing the Working Group One (WG1) contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2007), I’ve benefited enormously from the untiring dedication of the WG1 Technical Support Unit (and especially its head, Martin Manning). I’ve been awed by being able to work with over 170 truly gifted primary authors and review editors in our WG1 team. Their joint devotion to getting it right has been scrupulous and uplifting. The acknowledgment of IPCC in a Nobel Peace Prize shared with Mr. Albert Gore Jr. is an honor that belongs not only to thousands of scientists who worked on the IPCC over decades but more broadly to science as an enterprise. It signals a new message regarding the role of science in peace.

If I’ve been able to motivate younger people, it is mainly because it’s so compelling to work with colleagues such as I’ve enjoyed, on fascinating and important problems, in remarkable places like Antarctica: what a joy it is to be a scientist and what a joy it is to receive this wonderful Bowie Medal. Thank you.

—SUSAN SOLOMON, National Center for Atmospheric Research, Boulder, Colo.