The impact of stratospheric aerosol intervention on the North Atlantic and Quasi-Biennial Oscillations in the Geoengineering Model Intercomparison Project (GeoMIP) G6sulfur experiment

Abstract. As part of the Geoengineering Model Intercomparison Project a numerical experiment known as G6sulfur has been designed in which temperatures under high-forcing future scenario (SSP5-8.5) are reduced to those medium-forcing (SSP2-4.5) using proposed geoengineering technique stratospheric aerosol intervention (SAI). involves introducing sulfuric acid into tropical stratosphere where it reflects incoming sunlight back space, thus cooling planet. Here, we compare results from six Earth-system models that have performed and examine how SAI affects two important modes natural variability, northern wintertime North Atlantic Oscillation (NAO) Quasi-Biennial (QBO). Although all show is successful reducing global mean temperature designed, they also consistent showing forces an increasingly positive phase NAO injection rate increases over course 21st century, exacerbating precipitation reductions parts southern Europe compared with SSP5-8.5. In contrast robust result for NAO, there less consistency impact on QBO, but nevertheless indicate risk equatorial could cause QBO stall become locked permanent westerly winds lower stratosphere.