Effect of Pleistocene glaciation upon oceanographic characteristics of the North Pacific Ocean and Bering Sea

Abstract

During intervals of Pleistocene glaciation, insolation of the high-latitude northern hemisphere was lower than today, particularly during summer. Growth of continental ice sheets resulted in a lowering of sea level by more than 100 m in the Bering Sea. As a result, the Bering Strait was closed and most of the Bering continental shelf exposed. A proposed model predicts that (1) sea-ice formation would occur along the (modern) outer continental shelf, (2) advection would transport the sea ice over the deep basin, and (3) brine would flow into the basin at some intermediate depth to enhance the halocline. The result would be a low-salinity surface layer with a cold, thick halocline and reduced vertical mixing. Diatom microfossils and lithologic changes in sediment cores from the North Pacific Ocean and Bering Sea support the model and suggest that the proposed oceanographic conditions extended into the North Pacific, where the cold low-salinity layer was enhanced by meltwater from continentally derived icebergs.