thermohaline circulation, also called Global Ocean Conveyor or Great Ocean Conveyor Belt, the component of general oceanic circulation controlled by horizontal differences in temperature and salinity. It continually replaces seawater at depth with water from the surface and slowly replaces surface water elsewhere with water rising from deeper depths. Although this process is relatively slow, tremendous volumes of water are moved, which transport heat, nutrients, solids, and other materials vast distances. Thermohaline circulation also drives warmer surface waters poleward from the subtropics, which moderates the climate of Iceland and other coastal areas of Europe. A brief treatment of thermohaline circulation