ALTHOUGH ocean circulation and the consequent exchange of heat and gases with the atmosphere exert a strong influence on climate, discussions of global circulation have previously been highly schematic(1-3) (invoking laminar flow patterns that ignore the turbulent nature of the real flow), non-quantitative and/or based upon mutually inconsistent regional studies(1,8). Here we present a dynamically and kinematically consistent estimate of the magnitude and structure of global ocean circulation and its associated heat fluxes, derived by integrating hydrographic velocity data over the rapid spatial variations that they show. We find no single overturning cell, but instead a complex and probably time-varying circulation pattern. The simplest intel pretation suggests that there are two nearly independent cells : one connecting overturning irt the Atlantic Ocean to other basins through the Southern Ocean, and the other connecting the Indian and Pacific basins through the Indonesian archipelago.