Abstract

The Southern Ocean is an important regulator of the climate system, particularly in buffering atmospheric carbon dioxide (CO2) concentrations. Regions of high productivity associated with melting sea ice and downstream of islands establish the Scotia Sea as sustaining one of the most active biological carbon pumps.

Seasonal deficits in inorganic carbon during summer ice melt indicate that carbonate mineral precipitation had taken place in the sea ice. Combined with biological carbon uptake, this “sea ice carbon pump” created a sink for atmospheric CO2 at the ice edge. Extensive diatom blooms downstream of South Georgia created an intense summertime sink for atmospheric CO2 , the strongest biological carbon uptake in ice-free waters of the Southern Ocean to date.

The Scotia Sea is a mosaic of archetypal Southern Ocean environments and provides a natural mesocosm to investigate the processes that affect the marine carbon cycle of the contemporary and future Southern Ocean.