Global ocean thermohaline conveyor at present and in the late Quaternary

Operation modes of the global ocean thermohaline conveyor at present, at the last glacial maximum, and at a subsequent meltwater event (MWE) are revisited using a combination of a global ocean circulation model and a semi-Lagrangian trajectory tracing model. The trajectory tracing model helps to visualize the true three-dimensional water transport that is not accessible within traditional ocean circulation modeling. Our simulations confirm that the glacial mode of the conveyor was substantially weaker as compared to the present day mode. However, the simulations indicate that major changes of the deep global ocean conveyor occurred only at the MWE. These changes led to reversal of the Indian-Atlantic branch of the deep conveyor due to complete cessation of North Atlantic Deep Water production caused by a very localized meltwater impact.