Thermohaline circulation

Thermohaline circulation is the large-scale circulation of the world's oceans linked to the temperature and salinity of water masses. The cooled salt water plunges to the depths at high latitudes (off the coasts of Norway and Greenland). Water is reheated in the Tropics, and then rises to the surface, where it cools, and so on. A molecule of water is estimated to complete the entire circuit in about 1,000 years.