EAGER: Marine Sky Brightening: Prospects and Consequences

Indiana University, Bloomington IN

Investigators

Abstract

Solar geoengineering discussions have largely focused on stratospheric sulfate aerosols and Marine Cloud Brightening (MCB). However, both of these methods of solar geoengineering necessarily have limits in terms of their ranges of achievable climates, their potential side effects, and their uncertainties. Studying other methods of solar geoengineering is essential for expanding the options available to society for addressing climate change. Studies of Marine Sky Brightening (MSB) have the potential to fundamentally alter discourse about solar geoengineering, as well as open up new avenues of research that have been heretofore under-studied. This project is focused on MSB. Marine Sky Brightening (MSB) is a proposed method of solar geoengineering whereby sea salt particles are injected into the marine boundary layer. Like Marine Cloud Brightening (MCB), a related geoengineering technique, MSB would brighten clouds, increasing albedo and cooling the planet. However, preliminary modeling studies of MSB have shown that radiative forcing from direct scattering by the sea salt aerosols can be of a similar magnitude to radiative forcing from cloud brightening. Moreover, although MSB may be less efficient than MCB at exerting radiative forcing, it may not be as dependent upon local meteorological conditions: not all clouds can be brightened, and some areas that may be desirable to cool don't have clouds. This project includes a systematic exploration of MSB in a hierarchy of models, including radiative transfer models to understand optimal particle size for scattering, regional models and large eddy simulators to understand boundary layer dynamics and local climate effects. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.