Stratospheric ozone response to sulfate geoengineering: Results from the Geoengineering Model Intercomparison Project (GeoMIP)
G. Pitari, V. Aquila, B. Kravitz, A. Robock, S. Watanabe, I. Cionni, N. Luca, G. D. Genova, E. Mancini, and S. Tilmes
Journal of Geophysical Research, D: Atmospheres (16 March 2014)
DOI: 10.1002/2013JD020566
Geoengineering with stratospheric sulfate aerosols has been proposed as a means of temporarily cooling the planet, alleviating some of the side effects of anthropogenic CO2 emissions. However, one of the known side effects of stratospheric injections of sulfate aerosols under present-day conditions is a general decrease in ozone concentrations. Here we present the results from two general circulation models and two coupled chemistry-climate models within the experiments G3 and G4 of the Geoengineering Model Intercomparison Project. On average, the models simulate in G4 an increase in sulfate aerosol surface area density similar to conditions a year after the Mount Pinatubo eruption and a decrease in globally averaged ozone by 1.1−2.1 DU (Dobson unit, 1 DU = 0.001 atm cm) during the central decade of the experiment (2040–2049). Enhanced heterogeneous chemistry on sulfate aerosols leads to an ozone increase in low and middle latitudes, whereas enhanced heterogeneous reactions in polar regions and increased tropical upwelling lead to a reduction of stratospheric ozone. The increase in UV-B radiation at the surface due to ozone depletion is offset by the screening due to the aerosols in the tropics and midlatitudes, while in polar regions the UV-B radiation is increased by 5
keywords: geoengineering; intercomparison; ozone; 0340 Middle atmosphere: composition and chemistry; 0305 Aerosols and particles; 1627 Coupled models of the climate system