The role of the Southern Ocean in the Earth's climate system is assessed. This first involves exploring a series of simulations with a coupled climate model employing different Southern Ocean geometries - namely that of today's climate, a shallow Southern Ocean, and a Southern Ocean interrupted by a land bridge to Antarctica. We find that the North Atlantic thermohaline circulation depends not only on the existence of the Southern Ocean, but also on the bathymetry of the ocean around Antarctica. In contrast, Southern Hemisphere climate is highly sensitive to the existence of a circumpolar ocean, with the depth of the seafloor of secondary importance.

 

Beyond this paleo-perspective, I will assess the Southern Ocean's role in regional climate and climate change on time scales of years to centuries. Of particular interest is:

1. the response of the Southern Ocean to increasing atmospheric greenhouse gases,

2. the climate system response to latitude shifts in the subpolar westerly winds, and

3. the response of the Southern Ocean to Antarctic meltwater changes.