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GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L18209, doi:10.1029/2004GL020724, 2004

Southern Hemisphere climate response to ozone changes and greenhouse gas increases

Drew T. Shindell

NASA Goddard Institute for Space Studies, New York, New York, USA


Gavin A. Schmidt

NASA Goddard Institute for Space Studies, New York, New York, USA


Abstract

While most of the Earth warmed rapidly during recent decades, surface temperatures decreased significantly over most of Antarctica. This cooling is consistent with circulation changes associated with a shift in the Southern Annular Mode (SAM). It has been suggested that both Antarctic ozone depletion and increasing greenhouses gases have contributed to these trends. We show that a climate model including the stratosphere and both composition changes reproduces the vertical structure and seasonality of observed trends. We find that the two factors have had comparable surface impacts over recent decades, though ozone dominates above the middle troposphere. Projected impacts of the two factors on circulation over the next fifty years oppose one another, resulting in minimal trends. In contrast, their effects on surface climate reinforce one another, causing a departure from the SAM pattern and a turnabout in Antarctic temperatures, which rise more rapidly than elsewhere in the Southern Hemisphere.

Received 10 June 2004; accepted 24 August 2004; published 25 September 2004.

Index Terms: 0340 Atmospheric Composition and Structure: Middle atmosphere—composition and chemistry; 1620 Global Change: Climate dynamics (3309); 3362 Meteorology and Atmospheric Dynamics: Stratosphere/troposphere interactions; 3349 Meteorology and Atmospheric Dynamics: Polar meteorology; 9310 Information Related to Geographic Region: Antarctica.

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Citation: Shindell, D. T., and G. A. Schmidt (2004), Southern Hemisphere climate response to ozone changes and greenhouse gas increases, Geophys. Res. Lett., 31, L18209, doi:10.1029/2004GL020724.