Do warming oceans Portend an Ice Age?

• Position: Climate

It has been shown for the first time that the deep-ocean circulation system of the North Atlantic, which controls ice-age cycles of cold and warm periods in the Northern Hemisphere, is integrally coupled to salinity levels in the Caribbean Sea. University of California, Davis, research reinforces concerns that global warming, by melting the glacial ice of Greenland, quickly and profoundly could change salinity and temperatures in the North Atlantic Ocean. One consequence might be much colder weather in Northern Europe and Britain and perhaps even in eastern Canada and in the Northeast region of the U.S.

During Earth's warm periods, like the present one, surface ocean currents transport heat from the tropics to the cool northern latitudes. The new data, a record of Caribbean salinity for the past 120,000 years, show that, when the Northern Hemisphere warmed, Caribbean salinity levels dropped. The researchers hypothesize that elevated Caribbean salinity, which is transported via the Gulf Stream to the North Atlantic, amplifies the heat transport system by increasing the deep-ocean circulation rate. When the North Atlantic Ocean cools, the Caribbean's salinity begins building up because the deep ocean circulation drops to a fraction of its previous rate and the Gulf Stream no longer transports salty water away.

If...