Only in March did the Navy finally agree to declassify detailed maps of the ocean floor. Scientists argued that these data were essential to study the dynamic processes that shape the earth. Even without bureaucratic obstacles, collecting data at sea is difficult, costly and slow. Most oceanographic data are gathered on research ships that can make 10 knots, the same speed as the world's first oceanographic vessel, the H. M.S. Challenger , which explored the oceans in the 1870s. A major international push is now under way to measure and map ocean currents, a linchpin in the link between ocean and climate.
Scientists now know that at least half the heat is carried by vast ocean currents.
The speed of these currents is also of the essence. While virtually all agree that rising levels of carbon dioxide in the atmosphere are likely to cause climatic changes, they say that the current computer models that are the basis for predictions grossly simplify the role of the oceans and may give misleading results. But Hansen's model assumes that the oceans have no currents. Cold, deep water from Antarctica apparently would counteract the effect in the Southern Hemisphere. They are a positive menace.