Glacial Drainage Caused North Atlantic

Cold Snap That Lasted 200 to 400 Years Two vast glacial lakes that long ago gushed out of what is now northern Canada into the North Atlantic caused the most abrupt cold snap of the past 10,000 years, researchers at the University of Colorado in Boulder report in today's Nature. They estimate that more than 1 trillion cubic meters of water drained from the Agassiz and Ojibway lakes in the Hudson Bay region about 8,200 years ago, when a natural ice dam burst.

The deluge lowered the temperature of the northern Atlantic, causing a drop in mean air temperature of as much as 15 degrees in Greenland and 6 degrees in Europe that lasted 200 to 400 years. The ancient cold snap occurred because the water from the glacial lakes disrupted the temperature and salinity of the ocean. Surface currents carry warm water from the tropics into the North Atlantic, where it cools, becomes dense and sends heat into the atmosphere.

--Compiled by Times medical writer Thomas H. Maugh II

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