CAN REGULATION OF FRESH-WATER RUNOFF IN HUDSON-BAY AFFECT THE CLIMATEOF THE NORTH-ATLANTIC

A sequence of phenomena links anthropogenic changes in the timing of f reshwater runoff in Hudson Bay to a possible impact on the North Atlan tic thermohaline circulation. The chain of events starts with the spre ading of estuarine plumes under ice and continues with the effect of l owered salinity on the rate of ice formation, regional effects on the scale of Hudson Bay, the export of freshwater to the Labrador Sea, its impact on deep convection in that area, and the relative importance o f such changes to the North Atlantic circulation. At each step we comp are anthropogenic effects with other factors and place them within the perspective of natural variability. Our conclusion does not support t he contention that freshwater runoff regulation, even of all rivers in the basins of Hudson and James Bays, could have a significant or even a detectable effect on the climate of the North Atlantic.