Sensitivity of Arctic sea ice recovery to stratospheric aerosol injection latitude

Abstract Under multiple anthropogenic global warming scenarios considered by the Coupled Model Intercomparison Project Phase 6 (CMIP6), Arctic sea ice is projected to disappear seasonally as early as 2035. Stratospheric Aerosol Injection (SAI) is a climate intervention strategy that has been proposed to mitigate some of the impacts of global warming. In this study, we evaluate the effectiveness of SAI in preserving Arctic sea ice, focusing on its sensitivity to the injection latitude of the aerosols. Using the 2nd version of the Community Earth System Model (CESM2) coupled with the Whole Atmosphere Community Climate Model (WACCM6), we analyze experiments with aerosol injection latitudes ranging from 45°S to 45°N. The results reveal that as the injection latitude shifts closer to the North Pole, Arctic sea ice rapidly recovers in both its extent and volume. This recovery is driven by coordinated shifts in clear-sky and cloud-related radiation, along with changes in surface reflectivity, that collectively reshape the surface energy balance in favor of ice growth. Importantly, we also find that, under fixed SAI injection rates, Arctic sea ice recovery varies substantially with injection latitude and does not scale directly with global mean surface temperature.