Thermohaline Circulation (THC)
Thermohaline Circulation (THC)
A stream that circulates the globe within the oceans, made up of surface and deep water currents. It is produced by differences in densities created by varying water temperatures and salt content (influenced by freshwater inputs). In the North Atlantic Ocean, surface winds from the equator drive water towards the north pole (known individually as the Gulf Stream), whereupon it cools, becomes more dense and begins to sink. This forms deepwater and is intensified by the input of freshwater from ice melt, which likes to stay on the surface as it is less dense that saltwater. The cycle continues as this water then upwells in certain low latitude areas (closer to the equator), once again to be influenced by surface winds. A more detailed explanation and cycle map can be seen at http://en.wikipedia.org/wiki/Thermohaline_circulation.
This circulation is vital to the climate of the Earth because it transports heat energy around the globe. For example, if the Gulf Stream were to be shut down, the transfer of heat from the Gulf of Mexico to Northwest Europe would cease and Europe would suddenly become considerably colder.
Due to the fact that the circulation is influenced by freshwater input from ice melt, scientists worry that the increase in melt from global warming will transform the THC and so, once a threshold is reached, could suddenly change the climate that we know today.
The word ‘thermohaline’ comes from a combination of ‘thermal’ (meaning heat) and ‘haline’ (referring to salt).
For an animation and further explanation of the THC process, visit:
