"The Arctic As A Trigger For Glacial Terminations"
Walter Pitman, Lamont-Doherty Earth Observatory

ABSTRACT
During the last glaciation, the buildup of large continental ice-sheets in the Northern Hemisphere forced a more zonal circulation system. We hypothesize that this, in combination with the frigid (dry) polar air and southward migration of the northern ice-sheet edge led to a significant decrease in fresh water runoff into the Arctic Ocean. The freshwater contribution by the fresher Pacific water was completely eliminated by the emergence of the 50 m deep Bering Strait. As the Arctic freshwater input was depleted, regions of the Arctic Ocean lost surface stability and eventually overturned, bringing warmer deep water to the surface where it melted the overlying sea ice. This upwelled water was quickly cooled and sank as newly formed deep water. For sustained overturn events, such as those that might have occurred during the peak of very large glacial periods (such as the last glacial maximum), the voluminous deep water formed would eventually overflow into the Nordic Seas and Northern Atlantic (NA), initiating the onset of the thermohaline circulation. This deepwater outflow must have been replaced by a surface inflow breaking down the Arctic's zonal isolation, melting the expansive NA sea ice cover and initiating oceanic heating of the atmosphere over the ice sheets bordering the NA. We suggest that the combined effect of these overturn-induced events in concert with a Milankovitch warming cycle, was sufficient to drive the system to a termination.