Thermohaline circulation
Temperature & salinity variations cause variations in sea water density
Density variations drive vertical circulation called thermohaline circulation
- At poles, dense water masses at surface sink
- Surface waters move toward poles to replace sinking water
- Draw water to surface at low latitudes
- Deep waters flow from poles toward equator
Thermohaline circulation is slow; a parcel of water may take 100�s to 1000�s of years to make a circuit