Christian Claudel, Andrew John Lockley , Fabian Hoffmann, Younan Xia

Marine cloud brightening (MCB) is a proposed solar radiation modification (SRM) geoengineering technique to enhance marine boundary layer (MBL) cloud albedo. Extant proposals consider 10,000-100,000 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 500x (17x for the dry mass flux). This facilitates Unmanned Aerial Vehicle delivery (e.g. MQ-9 Reaper UAV). Increased speed, altitude and wake turbulence improves areal coverage per vehicle vs. ships - reducing fleet size. Utilizing extant airframe designs improves vehicle technology readiness level (TRL) - potentially improving system operational cost (est. $40B/year) and lead time. This approach further reduces energy requirements (5x less), technical risk and system complexity. Increased readiness amplifies proliferation risk - particularly for inexpensive regional heatwave and hurricane suppression - making governance more urgent.