The Younger Dryas: From whence the fresh water?

Oxygen isotopic records of meltwater outflow and records of sea level change do not support the idea that fresh waters derived solely from the melting of Northern Hemisphere ice sheets was likely to have stabilized the upper layers of the North Atlantic Ocean and prevented deep convection during the Younger Dryas. Yet there are paleoceanographic indicators that point to a pause in the formation of North Atlantic Deep Water during the Younger Dryas. This apparent conflict in evidence may be resolved by the existence of large, relatively thick, tabular icebergs that spilled out of the Arctic and into the Norwegian‐Greenland Sea and North Atlantic. The melting of large icebergs would have no impact on sea level but combined with meltwater runoff would provide enough fresh water to “cap” the North Atlantic. The timing of the start and the end of the Younger Dryas, however, may not have been directly related to freshwater supply.