A role for North Pacific salinity in stabilizing North Atlantic climate

Abstract

A simple ocean/atmosphere feedback may reduce the amplitude of climate variability in around the North Atlantic during interglacial compared to glacial states. When climate is warm in the North Atlantic region, the Intertropical Convergence Zone has a relatively northward position, and moisture is exported from the tropical Atlantic to the tropical Pacific. At the same time the east Asian summer monsoon is strong, which helps maintain a positive balance of precipitation over evaporation in the subpolar North Pacific. This is thought to account for lower salinity in the North Pacific relative to the North Atlantic, which, in turn, drives northward flow through the Bering Strait to the northern North Atlantic. Freshening in the North Atlantic by water of Pacific origin suppresses the meridional overturning circulation and reduces the heat flux. The opposite situation exists during cold climate. Thus the combination of atmospheric vapor transport and flow through Bering Strait tends to cool the North Atlantic region when warm and warm the region when cool.