Professor Emeritus

1936-2021

Ph.D., University of Washington
Aerosols, aerosol impacts on climate, aerosol instruments, CLAW hypothesis

Emeritus Professor Robert (Bob) Charlson was a faculty member at the University of Washington since 1965, beginning his faculty career in Civil Engineering and later moving to the Department of Atmospheric Sciences. Bob received a BS and MS in chemistry from Stanford University, and a PhD from our department in 1964 under the supervision of Konrad Büttner.

It is hard to overstate the impact that Bob’s research has had on the field of aerosol science in particular, and on the atmospheric sciences more broadly. He was a leader in demonstrating essential linkages in biological, geophysical and chemical phenomena. Bob was an inventor of multiple instruments to measure atmospheric aerosols, garnering him six patents. The nephelometer, which  measures light scattering by aerosols, resulted in the first patent to bear royalties for the University of Washington. It is still in broad use today around the globe.

As his many colleagues and graduate students could attest (he mentored 35 PhD and 8 MS students across his career at UW), Bob was a man of many ideas, and he generously shared these ideas with others. Bob wrote the first papers quantifying the global effects of anthropogenic aerosol pollution on the climate, both through direct interaction with sunlight, and through the effect of aerosol particles on clouds.

He conducted foundational work on the impacts of aerosol composition on the ability of particles to serve as cloud condensation nuclei. Bob’s most well-known paper focused on the potential for climate stabilization through a natural feedback loop involving the production of dimethylsulfide (DMS) by ocean phytoplankton. DMS is now recognized as the primary natural source of atmospheric sulfate aerosol. Now known as the CLAW hypothesis (after the last names of the contributing authors, Charlson, Jim Lovelock, Andi Andreae, and Steve Warren), CLAW hypothesized that DMS would increase the sunlight reflected by clouds and serve as a negative (stabilizing) feedback on climate warming. This work, as did many of Bob’s other papers, generated a wealth of new understanding about the importance of aerosol cloud interactions in the climate system.

Bob retired in 1999 and accepted an appointment by the King of Sweden to be his Professor of Environmental Science for the year 1999-2000. He was a contributing author on the 4th Assessment of the Intergovernmental Panel on Climate Change (IPCC) that won the 2007 Nobel Peace Prize, and continued to work with collaborators in the department, and around the world until this year. Bob began his career with instrumentation to make local, limited measurements, steadily broadening his interests and contributions over the years to focus on global biogeochemical systems, a unique trajectory.

Bob is survived by his wife, Pat, his children Daniel and Amanda, Dan’s wife Maureen, nieces Kathryn and Erika in California and eight grandchildren. Bob will be missed by the many students he mentored, his colleagues, friends and family.

Written by Robert Wood
Department of Atmospheric Sciences, Univ. of Washington, Seattle, WA, USA

Published: Atmospheric Circulation 2021 https://atmos.uw.edu/wp-dcontent/uploads/2021/12/AtmosphericSciencesNewsletter2021.pdf