TRANSPORT OF HEAT, CO2 AND O-2 BY THE ATLANTICS THERMOHALINE CIRCULATION

We estimate transport of heat, CO2 and O-2 by the Atlantic's thermohal ine circulation using an approach based on differences in the chemical and physical characteristics of North Atlantic Deep Water (NADW), Ant arctic Intermediate Water (AAIW), and the northward return flow across the equator. The characteristics of the return-flow waters are constr ained by imposing conservation of phosphate in the North Atlantic as a whole. Based on a total equatorial return flow of 13 x 10(6) m(3) s(- 1), we find that the Atlantic north of the equator is a source of 7.7 +/- 1.4 x 10(14) W to the atmosphere, a sink of 0.51 +/- 0.21 x 10(14) mol of O-2, and preindustrially was a sink of 0.33 +/- 0.15 x 10(14) mol of CO2. Uptake of O-2 and CO2 by the North Atlantic is driven main ly by thermal, as opposed to biological processes.