Effects of sea salt aerosol emissions for Marine Cloud Brightening on atmospheric chemistry: Implications for radiative forcing
Abstract:
In light of global warming, hypothetical geoengineering methods have been proposed to try to counteract rising temperatures. One, marine cloud brightening (MCB), involves spraying sea salt aerosol particles into the tropical marine boundary layer. This increases aerosol and cloud albedo and reflects additional sunlight away from the Earth. The effects of the additional sea salt on atmospheric chemistry have not previously been explored. Sea salt aerosol is the main source of reactive chlorine (Cly) and bromine (Bry) in the troposphere. Their resulting chemical reactions affect the amount of ozone and methane, both greenhouse gases, as well as the formation of sulfate-nitrate-ammonium particles, which may further impact radiative forcing and air quality. We simulate a range of sea salt aerosol injections for MCB in the GEOS-Chem global chemical transport model, only considering their impacts as a halogen source, and quantify their effects on major atmospheric oxidants, air pollutants, and greenhouse gases throughout the troposphere. We will present implications for air quality and radiative forcing considering these effects. Our results suggest atmospheric chemistry impacts may be important to consider when evaluating geoengineering methods.
