THE OCEANS OVERTURNING CIRCULATION

The ocean is a mysterious place. As terrestrial creatures, we are familiar with a small volume of relatively warm ocean water near the surface. The deep ocean is not so familiar. Isolated from the thermal energy of the Sun and the mechanical energy of atmospheric winds, the deep ocean is completely dark and filled with nearfreezing water. Yet the deep ocean is far from stagnant. Radioactive tracer measurements show that the ocean's circulation brings its interior water into contact with the atmosphere every 600 years or so.Each second millions of cubic meters of water circulate between the ocean's surface and its depths. Despite the crucial role this overturning may play in regulating Earth's climate, we still do not know how vulnerable it is to anthropogenic environmental changes. © 1994, American Institute of Physics. All rights reserved.