Abstract

The Southern Ocean and the Antarctic Circumpolar Current, its principle zonal current system, are typically viewed as being of global significance to the Earth’s climate. Furthermore, the close relationship between Antarctic temperature and atmospheric carbon dioxide suggests an important role for the Southern Ocean in glacial cycles. It has been hypothesised that changes in Southern Ocean wind stress might drive the glacial/inter-glacial cycle in carbon dioxide. However, the resolution of the mesoscale eddy field, which is of dynamical importance to the Southern Ocean, fundamentally alters the sensitivity of the Southern Ocean circulation to changes in wind stress in numerical models. Recent eddy-resolving model results indicate that in the presence of a vigorous eddy field, the sensitivity of Southern Ocean upwelling and global stratification to changes in Southern Ocean wind stress may be low. This may limit the sensitivity of the climate system as a whole to changes in Southern Ocean wind stress, by limiting the change in ventilation of abyssal carbon reservoirs. Numerical experiments with an idealised mode configuration indicate that the eddy field not only alters the sensitivity of the physical circulation, but also the ocean carbon storage and its decomposition into physical and biological storage terms.