CONTRIBUTION OF SOUTHERN-OCEAN SURFACE-WATER STRATIFICATION TO LOW ATMOSPHERIC CO2 CONCENTRATIONS DURING THE LAST GLACIAL PERIOD

The nitrogen-isotope record preserved in Southern Ocean sediments, alo ng with several geochemical tracers for the settling fluxes of biogeni c matter, reveals patterns of past nutrient supply to phytoplankton an d surface-water stratification in this oceanic region. Areal averaging of these spatial patterns indicates that reduction of the CO2 'leak' from ocean to atmosphere by increased surface-water stratification sou th of the Polar Front made a greater contribution to the lowering of a tmospheric CO2 concentration during the Last Glacial Maximum than did the increased export of organic carbon from surface to deep waters occ urring further north.