ROLE OF THE BERING STRAIT IN CONTROLLING NORTH-ATLANTIC OCEAN CIRCULATION AND CLIMATE

RECENT climate records from ice cores and deep-sea sediments suggest t hat there has been considerable climate variability in the North Atlan tic region over the past 250,000 years1-3. Much of this variability ma y be linked to changes in thermohaline circulation in the North Atlant ic ocean4-6. Model studies7-9 have demonstrated that changes in the fl ux of fresh water to the ocean, resulting from changes in atmospheric transport or the waxing and waning of ice sheets, can have a significa nt effect on the thermohaline circulation. Here we present model simul ations showing that increased flow of fresher North Pacific water thro ugh the Bering Strait into the northern North Atlantic can also affect the thermohaline circulation, by suppressing North Atlantic Deep Wate r formation; however, decreased flow does not necessarily cause deep-w ater formation to begin again. In our model, flow through the Bering S trait depends on eustatic sea level and the salinity difference betwee n the North Atlantic and North Pacific oceans. We suggest that the hig her sea level during the last interglacial period10, leading to greate r flow through the Bering Strait, may have made the North Atlantic the rmohaline circulation more sensitive than it is at present to fluctuat ions in the hydrological cycle, which may explain recent observations1 indicating that climate variability was greater then than it is today .