The WMO Scientific Assessment of Ozone Depletion in 2018 has stated that geoengineering applications using stratospheric aerosols would alter stratospheric ozone. However, estimated amount and for some regions the sign of ozone changes are uncertain and depend on various factors, including injection strategies, amount, timing, and type of particles used. Going forward, the range of ozone changes and the sensitivities to different parameters have to be better quantified in order to produce an improved understanding of the impacts of stratospheric aerosol geoengineering. In this presentation, I will employ results from the Whole Atmosphere Community Climate Model (WACCM) and present the sensitivity of ozone changes with stratospheric sulfate geoengineering dependent on injection locations, high and low altitude injections, and equatorial injections. Furthermore, results from different model versions and different future pathways are presented. Those include simulations from the WACCM Geoengineering Large Ensemble (GLENS) project based on the RCP8.5 future pathway, a 110-layer WACCM version (with higher vertical resolution), and new results from WACCM6 based on SSP5-85 and the SSP5-34 overshoot pathway. Finally, I would like to discuss a set of geoengineering experiments to be performed by other models that are part of the Chemistry Climate Model Initiative (CCMI) and GeoMIP, in order to better quantify the effects of geoengineering on chemistry and dynamics.
Simone Tilmes is a Project Scientist II at National Center for Atmospheric Research (NCAR) and the liaison for the Community Earth System Model (CESM) chemistry-climate working group and has been working for many years on the topic of geoengineering.
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