Thermohaline circulation brings oxygen rich water to the deep ocean.

Thermohaline circulation is also called overturning circulation. It is driven by density. The time scale for thermohaine is 1000 years.

Thermohaline circulation is what causes the vertical motion in ocean currents. The main forces behind thermohaline circulation are the differences in temperature and salinity in bodies of water.

The thermohaline circulation is driven by surface heat (insolaration) and freshwater flows. These change the density of the ocean's water and gravity does the work.

Global Ocean Conveyor