Impacts of Atmospheric Deposition due to Climate Intervention

• These three G6 models cannot be combined into an ensemble. • The models do not treat solar reduction the same way. They all manage to decrease from SSP5-8.5 to SSP2-4.5 by the end of the century but they use different approaches • Start in 2020 with SSP5-8.5 emissions • Add aerosol optical depth • UKESM-1 injects SO2 uniformly between 10? N and 10? S between 18 and 20 km of altitude and across a single longitudinal band (? 0). This value is adjusted every decade. • CESM2-WACCM injects SO2 at the equator at an altitude of 25 km. This value is adjusted annually. • CNRM-ESM2 uses an input dataset from a different GeoMIP experiment to prescribe the aerosol optical depth distribution. This value is adjusted annually. • There are also different features included in the simulated stratosphere and aerosol transport and deposition. • UKESM1 and CESM2-WACCM have good agreement for the tropical and high-latitude AOD whereas CNRM-ESM2 is very different. • The amount of SO₂ required varies between models by as much as 10 Tg • The injection altitude is not the same between models and so the stratospheric heating caused by the additional SO₂ will cause differences in temperature and precipitation.