"Stratospheric aerosol: uncertainties in current understanding and implications for solar geoengineering"
Frank Keutsch, Stonington Professor of Engineering and Atmospheric Science and Professor of Chemistry and Chemical Biology, Harvard School of Engineering and Applied Sciences
David Keith, Faculty Associate. Gordon McKay Professor of Applied Physics, Harvard John A. Paulson School of Engineering and Applied Sciences; Professor of Public Policy, Harvard Kennedy School.
Stratospheric aerosol has usually been assumed to consist of a mixture of sulfuric acid and water. This assumption has been used to determine chemical reactivity, for example for ozone, and physical properties, for example absorption coefficients. However, over the last decade limited measurements have shown that stratospheric aerosol is much more varied, often containing large amounts of organic material, than previously assumed. These findings are not being considered in models of stratospheric chemistry or radiation, primarily due to large uncertainties. I will discuss the current state of understanding and implications for solar geoengineering.