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Stratospheric ozone response to sulfate geoengineering: Results from the Geoengineering Model Intercomparison Project (GeoMIP)
Author(s) -
Pitari Giovanni,
Aquila Valentina,
Kravitz Ben,
Robock Alan,
Watanabe Shingo,
Cionni Irene,
Luca Natalia De,
Genova Glauco Di,
Mancini Eva,
Tilmes Simone
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd020566
Subject(s) - sulfate aerosol , ozone depletion , atmospheric sciences , ozone , sulfate , environmental science , radiative forcing , stratosphere , climatology , ozone layer , coupled model intercomparison project , aerosol , geoengineering , polar , middle latitudes , climate model , chemistry , climate change , meteorology , geology , oceanography , geography , physics , astronomy , organic chemistry
Abstract Geoengineering with stratospheric sulfate aerosols has been proposed as a means of temporarily cooling the planet, alleviating some of the side effects of anthropogenic CO 2 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% on average, with 12% peak increases during springtime. The contribution of ozone changes to the tropopause radiative forcing during 2040–2049 is found to be less than −0.1 W m −2 . After 2050, because of decreasing ClO x concentrations, the suppression of the NO x cycle becomes more important than destruction of ozone by ClO x , causing an increase in total stratospheric ozone.