Climate Impact of Marine Cloud Brightening Solar Climate Intervention Under a Susceptibility‐Based Strategy Simulated by CESM2

Abstract The efficiency of marine cloud brightening in cooling Earth's surface temperature is investigated using an ensemble of simulations with the Community Earth System Model version 2 (CESM2). We employ a susceptibility‐based cloud seeding strategy, previously developed under the Community Climate System Model version 3 (CCSM3) to counteract the warming of CO 2 doubling, in which we target the regions of the ocean most easily brightened, to determine what area extent will be required to induce 1°C cooling under SSP2‐4.5. The results indicate that cloud seeding over 5% of the ocean area is capable of achieving this goal in CESM2. Under this seeding scheme, cloud seeding is mainly deployed over lower latitudes which leads to a La Niña‐like pattern of response which is a major unintended consequence. Potential mechanisms behind such side effects are presented and discussed. The simulations also reveal that the 5% cloud seeding scheme induces an overall reduction in global precipitation, with an increase over land and a decrease over the ocean.