Northern Hemisphere Blocking Highs in a Solar Radiation Management Scenario

Abstract

Solar Radiation Management (SRM) has been rising in popularity as a potential method to offset climate warming due to increased greenhouse gases (GHG). The response of climate to geoengineering remains a challenge and has been studied under idealized experiment design in the Geoengineering Model Intercomparison Project (GeoMIP). The GCM CESM(WACCM) Geoengineering large ensemble (GLENS) was created to help gain insight into geoengineering impacts when stratospheric sulphate is injected in the tropics as to keep a set of surface temperature goals in 2020 levels. Blocking highs are a high impact synoptic-scale feature, associated with cold-spells and heat-waves in Europe. For this thesis, the change in blocking occurrence, under the GLENS SRM scenario, was studied using two meridional geopotential inversion methods: Tibaldi and Molteni (1990) and Barnes et al. (2012). It was found that overall blocking frequency increases in relation to a control (RCP8.5) scenario, and keeps other regional and seasonal features in relation to the starting period, unlike the control. These changes have a high correlation to the NAM behaviour. Persistence and extent of blocks show no significant change.