Evaluation of the Climate Impacts of the Stratospheric Aerosol Injection with Solar Powered Lofting

Stratospheric aerosol injection (SAI) introduces large amounts of climate intervention (CI) material in the stratosphere to reflect more sunlight back to space. Previous study (Gao et al., 2021) explored a novel delivery method named solar-powered lofting (SPL) which lofts CI material injected from the troposphere to the stratosphere. In SPL, a small amount of black carbon (BC) is injected with the CI material and heats the surrounding air. The heated air with the injected CI material rises into the stratosphere. In this study, we use the Community Earth System Model version 1 Whole Atmosphere Community Climate Model (CESM1(WACCM)) coupled with the three-mode version of the Modal Aerosol Model (MAM3) to explore the impacts of SPL relative to the traditional SAI method with focus on the stratospheric temperature, ozone distributions and the atmospheric circulation. In SPL methods, 20 Gg BC is injected each year and the simulated stratospheric BC budget is 13.5Gg, 15% of the BC budget in the troposphere. Compared with the traditional SAI that delivers CI material at 20 km, SPL method provides similar zonal mean aerosol optical depth and effective radiative forcing. However, our study shows that SPL warms the annual mean tropical stratosphere by 1.2K more compared with the traditional SAI. The change in the stratospheric ozone budget and brewer-dobson circulation are compared between various SAI approaches.
References:
Gao et al.2021