The Impact of the Ozone Hole on the Climate of the Southern Hemisphere

The dramatic depletion of the Antarctic ozone since the late 1970s has introduced a major perturbation to the radiative balance of the stratosphere with a wide range of consequences for climate. There is strong evidence that ozone loss has significantly altered the climate of the southern hemisphere troposphere, including the surface, with implications for ocean circulation, the cryosphere and coupled carbon cycle. As ozone depletion recovers in the next half-century or so, a corresponding reversal of these changes can be expected, providing an unprecedented opportunity to observe how the climate system relaxes from a known perturbation. The effort proposed here focuses on improving the understanding of current southern hemisphere climate changes linked to ozone depletion, so that we can better prepare to maximize the learning experience represented by the future healing of the ozone hole through identification of mechanisms, impacts, and observable indicators.

The Southern Hemisphere is of huge importance to the trajectory of the global climate system and presents a fascinating intellectual and modeling challenge involving interdisciplinary study of the coupling of the stratosphere, troposphere and ocean; coupling of chemistry, radiation and dynamics in the stratosphere; coupling of the ocean, ice and atmosphere at the earth?s surface; the coupling of the carbon cycle to ocean dynamics. The problem is multiscale and multi-component that requires the bringing together of atmospheric chemistry, ocean biogeochemistry, sea-ice dynamics together with atmospheric and ocean dynamics and transport.

To tackle this problem we have assembled an interdisciplinary team of researchers from MIT, Columbia University, Johns Hopkins University and NCAR, whose expertise covers the above areas. A suite of models of different complexity will be deployed to explore the mechanisms, impacts and indicators of the Antarctic stratospheric ozone hole and its recovery on the climate of the atmosphere-oceanice- carbon system. To this end we will explore: (i) how interactive chemistry modifies the coupling between the stratospheric vortex and the rest of the climate system (ii) resulting changes in ocean circulation, ice cover, heat and carbon uptake, and biogeochemistry of the southern ocean (iii) the impacts and observable indicators of the ozone hole on the global climate.

Intellectual merit: The problem outlined here is one of the most challenging in climate science demanding the development and deployment of a modeling hierarchy that arcs from the stratosphere to the interior ocean and couples chemistry, radiation, fluid dynamics, ice dynamics and the carbon cycle. Moreover, it is one that is amenable to study in the context of the instrumental record. An important product of the study is to make an initial list of climate indicators that could be used to monitor the rebound of SH climate from the ozone hole and its evolution over the next few decades in the presence of ever increasing greenhouse gas forcing.

Broader Impacts: We will extend ongoing activity at MIT and Northeastern University in which K-12 teachers are educated about climate science in the context of national science curriculum development and include some of these activities in K-12 programs at JHU and Columbia. We also propose to host and engage in our research and educational activities Summer Research Program (MSRP) students at MIT, an institutional effort that facilitates the involvement of talented students in engineering and science research, particularly those from underrepresented groups. Finally we propose to engage the broad science community on southern hemisphere climate change through two workshops, including developing a community view on indicators and needed observations.