The thermohaline ocean circulation (THC) of the Atlantic ocean is a density-driven large scale overturning motion with relatively warm surface waters flowing northward and cold North Atlantic Deep Water (NADW) returning southward at 2-3 km depth. This circulation carries heat northward at a rate of up to 1PW (1015 W ) and has a significant effect on the climate in Western Europe. The air over the northern North Atlantic is assumed to be warmed by up to ~ 10 degrees in the annual mean, with its largest effect occurring in winter when oceanic heat release is at its maximum and solar heating at its minimum. Paleoclimate reconstructions show that the Atlantic circulation has been subject to large and rapid changes throughout the last ICE Age. We study such rapid changes between different models of the THC using a hierarchy of models ranging from simple conceptional models to models of intermediate complexity.
This work has been done in collaboration with Stephan Rahmstorf and