Thermohaline circulation has been considered to be driven by localized buoyancy loss through the sea surface at high latitudes and broadly distributed buoyancy gain elsewhere. Our numerical modeling study, however, shows that buoyancy gain for the Atlantic deep circulation is localized in the Southern Ocean. Wind-induced upwelling there causes efficient heat transfer to the deep ocean, and controls intensity of the Atlantic deep circulation as thermohaline circulation. ¿ 1999 American Geophysical Union