Chemist Marissa Weichman wins Packard Fellowship to study one of the least-understood aspects of climate change

Marissa Weichman, an assistant professor in the Department of Chemistry, has been awarded a 2023 Packard Fellowship for Science and Engineering by the David and Lucile Packard Foundation for her proposal to study atmospheric aerosols and their potential role in climate change.

Weichman is one of 20 scientists nationwide to receive the prestigious, early-career fellowship, among the nation’s largest nongovernmental awards. Designed to allow maximum flexibility in the use of award funds, the Foundation allots $875,000 over five years to each fellow to spend on research as they wish. Fellowships are awarded to encourage innovative, blue-sky thinking that could one day foster discoveries to improve lives and broaden our understanding of the universe.

Weichman, a physical chemist, was selected for her proposal “The Stratosphere in Focus: New Spectroscopic Tools for Aerosol Science.”

“I’m especially thrilled with this fellowship to get to join the community that comes with being a Packard Fellow — all people who are doing such exciting things in their fields across scientific boundaries,” said Weichman. “I’m excited to meet my cohort of fellows on the tenure track, so it really is about finding peers and forming those bonds that are so inspiring.

“The Foundation gives you the startup money without restrictions, recognizing that maybe you’ll have other great ideas or there’s something else that you think of tomorrow that you might want to do,” Weichman added. “So for the next five years, that flexibility allows me to go for bigger, riskier ideas that can have greater impact.”

Paul Chirik, Princeton's Edwards S. Sanford Professor of Chemistry and the chair of the department, said: “This highly competitive award speaks to what we all know at Princeton: that Marissa is a superb scientist, teacher and colleague. Just a few years into her independent career, she has developed an impactful and visible program on light-matter interactions. As a former Packard fellow, I know these awards allow for the freedom to explore new, high-risk, high-reward ideas outside the realm of traditional funding streams. I have no doubt Marissa will make the most of this opportunity.”

“We're going to look at a single particle”

Weichman plans to use spectroscopic techniques to investigate uncertainties around the role of aerosols in the atmosphere and their involvement in climate change.

Aerosols are ubiquitous, micro-sized particles suspended in the air — such as water droplets, dust and soot — that influence two phenomena central to the Earth’s climate and weather: the scattering of sunlight and the seeding of clouds. These roles, however, are poorly understood. Weichman will look at how a particle’s size and composition influences its chemistry, the scattering and absorption of light, and its ability to seed cloud droplets.

“Aerosol-light and aerosol-cloud interactions remain the largest sources of uncertainty in our best models of Earth’s radiative balance. Our current knowledge of these intricate systems is not sufficient to capture their role in the climate crisis, much less predict the impact of potential climate interventions,” said Weichman.

“All of these complicated interactions depend on the size of the particle and its composition. If you’re measuring how these particles behave and averaging over millions of particles of various sizes and compositions, you’ll never be able to understand what’s actually happening.

“So instead, we’re going to look at a single particle. Let’s hold one single salt particle or dust particle, trap it with electromagnetic fields and hold it in place for minutes or hours or days, and watch what happens under a battery of simulated atmospheric conditions.”

Weichman believes the data gathered in her lab will provide a strong foundation for decisions about solar radiation management strategies and other efforts to counteract global warming.

The daughter and granddaughter of physicists, Weichman was born in California and raised in California, Colorado, and Massachusetts. She also has family roots in the Princeton area. She joined Princeton chemistry in 2020 from the University of Colorado-Boulder, where she was a postdoctoral fellow. She received her B.S. in chemistry from the California Institute of Technology and her Ph.D. in chemistry from the University of California-Berkeley.

In recent years, she has received a Faculty Early Career Development (CAREER) grant from the National Science Foundation, a next-generation STEM grant from the Department of Energy Office of Science’s Early Career Research Program, and a seed grant from the American Chemical Society Petroleum Research Fund through the Doctoral New Investigators Program.

Along with her position in the Department of Chemistry, Weichman is associated faculty in the Princeton Quantum Initiative, the Princeton Materials Institute and the High Meadows Environmental Institute.