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Submitted by George Elliott on Sun, 07/14/2013 - 9:00am.
We know the atmosphere is in constant flux and motion. Just witness the daily changing weather patterns. For that matter, the minute to minute changes from the ground level to thousands and thousands of feet into our near-earth atmosphere. Well, the same can be said about the world’s oceans.
Our oceans are certainly not a stand still body of mass. There is constant motion in the ocean in the form of a global ocean “conveyor belt”. The motions are due to what are called “thermohaline” currents (thermo, meaning temperature, and haline, meaning salinity).
Cold and salty water is much denser than warmer and less salty water. As a result, cold water sinks toward the bottom of oceans, and warm and less salty and dense water rises to the top, displaced by the sinking cold, salty, dense water.
The ocean conveyor gets it “start” in the Norwegian Sea, where warm water from the Gulf Stream looses heat into the atmosphere of the colder air over the northern latitudes. The loss of heat into the atmosphere cools the upper layers of the ocean, causing it to sink toward the bottom.
As warm water continues to flow northward in this conveyer belt, the sinking cold water, being displaced toward the bottom, begins a journey south toward the warmer southern latitudes once again. This cold bottom water flows south of the equator all the way down to Antarctica.
As the cold water near the bottom moves south, it eventually moderates and warms, begins to rise back to the top of the ocean, and thus begins the journey back north in the global circulation patterns of the oceans.
But, it takes a while. As a matter of fact, for any individual particle of water, it takes about 1,000 years to make a complete global circulation from where it began. Slow, yes, but steady. As climate changes, so too is the oceanic circulation. To what extent, and to what ultimate outcome, is a matter of scientific inquiry and debate.
By: George Elliott