Uncertainties in Processes for Stratospheric Aerosol Injection: Why Volcanoes Aren’t Enough and the Need for Field Experiments

Stratospheric aerosol injection (SAI) is the idea that aerosol precursors could be released into the stratosphere, where the resulting aerosols would linger and reflect incoming solar radiation, counteracting some fraction of anthropogenic warming. We know SAI would work because of volcanoes: when a volcanic eruption deposits SO2 into the stratosphere, it oxidizes to H2SO4, which forms reflective sulfate aerosols, cooling the planet. Volcanic eruptions are used to validate or tune aerosols in climate models, but the processes in an SO2 plume injected from an aircraft differ from those in a volcanic plume in important ways. Dr. Marianna Linz, Head of Research for Reflective, will walk through these differences in processes, summarize what we know and do not know about them, show which ones matter the most for aerosol evolution, and discuss how we can make progress on understanding those critical uncertainties. She will highlight those where we will need a field experiment to understand the implications of the interactions between processes and describe a hypothetical experiment. By focusing on resolving uncertainties at the process level, she argues that we can design these modest experiments with clear scientific questions and observing strategies structured to answer those questions.

Marianna Linz, Reflective's Head of Research, brings expertise in a broad range of topics within climate dynamics, including large-scale patterns of winds and ozone in the stratosphere, temperature extremes at the surface, and global heat transport in the ocean. Marianna was an undergraduate at Harvard University before pursuing her PhD in Physical Oceanography at the Massachusetts Institute of Technology joint program with the Woods Hole Oceanographic Institute. She spent two years as a postdoc at UCLA and then joined Harvard in 2019. In her role as an Assistant Professor of Environmental Science and Engineering and Earth and Planetary Sciences, she uses theory, simple models, complex models, and observations to decode the relationships between winds or currents and the substances they transport so that we can better understand how the distributions of heat, carbon, and air pollutants will change in a warming world.