Marine-cloud brightening: an airborne concept

Abstract

Marine Cloud Brightening (MCB) is a proposed Solar Radiation Modification (SRM) geoengineering technique to enhance Marine Boundary Layer (MBL) cloud albedo. Extant proposals consider 104 − 105 autonomous ships spraying seawater, generating and dispersing sea salt nanoparticles. Alternatively, this paper proposes industrially manufacturing NaCl nanoparticles using ethanol anti-solvent brine precipitation. With desiccation, size optimization and narrowed size distribution, aerosol mass flux reduces by ∼500× (17× for dry mass flux). This facilitates Unmanned Aerial Vehicle delivery (e.g. MQ-9 Reaper Unmanned Aerial Vehicle). Increased speed and wake turbulence improves areal coverage per vehicle versus ships—reducing fleet size. Utilizing extant airframe designs improves vehicle Technology Readiness Level (TRL)—potentially improving system operational cost (est. $40B · yr −1) and lead time. This approach further reduces energy requirements (5× less), technical risk and system complexity. Increased readiness amplifies proliferation risk—particularly for inexpensive regional heatwave and hurricane suppression—making governance more urgent.