4.1.14 (HL)—Thermohaline circulation

Thermohaline circulation arises from density differences caused by temperature and salinity: cold, salty water can sink and drive deep flow.

North Atlantic surface water loses heat and may become saline enough to sink; deep currents connect basins while compensating upper flows redistribute heat. Freshwater input can inhibit sinking, and winds also drive surface currents.

Meltwater freshens a sinking region, lowers surface density and weakens the downward branch even if cooling continues.

Salinity matters too; warm salty water can be denser than fresher cold water, so use both variables.

Thermohaline circulation is a network, not one conveyor belt with a fixed speed or route.