Stratospheric Ozone Depletion and Recovery and Antarctic Climate Change

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Climate change in the Antarctic, along with its several global consequences (e.g. sea-level rise associated with surface mass balance of the Antarctic ice sheet) are often attributed in terms of rising greenhouse-gas (GHG) forcing. Ozone, especially that residing in the stratosphere, is another radiatively important gas whose past anthropogenic depletion also has climate consequences e.g. intensification of the polar night jet during spring. GHG concentrations will continue to rise over the remainder of this century, whereas stratospheric ozone is expected to recover, following the Montreal Protocol, leaving some uncertainty in the resulting circulation trends in the Southern Hemisphere. Linkages between ozone change and four aspects of Antarctic climate namely: i) Antarctic surface temperatures, ii) cloud cover, iii) sea-ice and ice-sheet mass balance will be investigated by a series of earth systems model experiments. Two different types of models will be utilized, the first being a coupled chemistry-climate model, the Whole Atmosphere Community Climate Model (WACCM). The second will be a stand-alone ice sheet model, the Ice Sheet System Model (ISSM), which will be forced with the atmospheric fields from the WACCM runs. Simulations that only vary atmospheric greenhouse gas (GHG) amounts will further permit comparison between future ozone and GHG climate effects. These large scale climate effects are also of direct societal and economic interest. Antarctic climate and environmental change has far reaching impacts through its ties to biogeochemical cycling of carbon, ocean circulation and global sea level rise. The latter are highly relevant to society, and thus understanding the causes of Antarctic climate change