The North Pacific's role in Pleistocene climate

The presence of a strong halocline in the North Pacific currently suppresses deepwater formation. Here we discuss paleo-proxy and modeling evidence to suggest that this has not always been the case. Higher subpolar salinity values for instance during stadial events may have triggered deep convection in the Bering Sea and the Gulf of Alaska, leading to a "rewiring" of the global conveyor belt circulation and the development of a deep Pacific Meridional Overturning Circulation cell (PMOC). Here we review the effects of a PMOC on global climate, as well as the mechanisms that lead to a weathering of the North Pacific halocline on orbital and suborbital timescales. To confirm the notion that the North Pacific has served as a "backup-generator" for the global climate system during periods when the Atlantic Meridional Overturning Circulation was weak, we compare our latest modeling results with high resolution paleo proxy data from the Sea of Okhotsk and the Bering Sea.