Simulated changes in the extratropical Southern Hemisphere winds and currents

The results from 12 global climate models show a remarkably consistent strengthening and poleward shifting of the zonal wind stress through the 20th and 21st centuries at extratropical Southern Hemisphere latitudes. Changes in the zonal circulation of the ocean in the region are broadly consistent with the changes in zonal wind stress. In particular, the climate models simulate a strengthening and a poleward shift of the Antarctic Circumpolar Current. The strengthening of the zonal wind stress also results in intensifying northward Ekman transport across the Antarctic Circumpolar Current which, in the unblocked latitudes of Drake Passage, implies increasing southward geostrophic transport in the ocean below about 2000 m. Zonal wind stress changes such as these may be expected to enhance the mesoscale eddy activity in the Southern Ocean.