Dr David Marshall, University of Oxford, UK
2010 Starr Lecture
The Antarctic Circumpolar Current (ACC) is the largest global ocean current, transporting roughly 130 million cubic meters of water around Antarctica every second. The strength of the ACC is intimately connected with the stratification of the ocean basins to the north and has a strong influence on oceanic heat and carbon content. Understanding the dynamics of the ACC and its adjustment is therefore an important element of understanding the ocean's role in climate change, both in response to anthropogenic forcing, and in past glacial cycles. In this talk Dr Marshall will review some recent developments in our understanding of processes that set the equilibrium strength of the ACC and its adjustment to changes in forcing. A disturbing conclusion is that both the equilibrium ACC and its adjustment depend critically on Southern Ocean eddies, occuring on small spatial scales (10s of km) and crudely represented in the ocean models currently used for climate prediction. He will also present preliminary results from a simple "eddy-permitting box model" of the oceans that partially resolves ocean eddies and can be run to equilibrium over 1000s of years, to study the potential roles of the oceans in glacial cycles.