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Océan et climat

Jacques Merle


George Philander

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1The second half of the 20th century was a most remarkable period in the history of oceanography. In the 1980’s oceanographers were still determining the position of a ship at sea by means of stars and sextants, the instruments of explorers, of individualists who brave the elements and venture into uncharted territory in search of new worlds. Today it is possible to locate a ship very accurately by means of the Global Positioning System, (GPS) which depends on several satellites in space. How did such astonishing technological changes affect, not only the science of oceanography, but also the relationship between oceanographers and the sea? What political and sociological changes accompanied these developments?

2Originally the oceans were studied mainly for the practical purpose of making journeys across the oceans shorter and safer. Studies of the ocean for its own sake-of conditions far below the surface for example-started in the second half of the 19th century with expeditions sponsored by varions European colonial powers. The results were often published in atlases because, beneath its restless surface, the ocean was assumed to be unchanging. By the time of World War II the sum of all the measurements made on the varions expeditions enabled oceanographers to arrive at a fairly accurate picture of the varions components of the oceanic circulation. (The only major current to go unnoticed was the Equatorial Undercurrent whose discovery is an engaging subplot of this book.)

3The end of World War II brought an increase in the resources available to oceanographers, and remarkable freedom to pursue science for the sake of science. This was a consequence of the Cold War which reached its peak with the launching of the first artificial satellite, Sputnik, by the former USSR, in 1957. Concern that the west may have fallen behind the Soviet Union in science caused this event to be a bonanza for science in general, and for oceanography in particular. The large increase in the number of scientists entering the field of oceanography led to radical changes in the problems oceanographers started addressing, and in the way they conducted their affairs.

4At the beginning of this period it was widely believed that the ocean, below its restless surface, is unchanging, but attention then shifted to oceanic variability, to the “weather” of the ocean. The need for simultaneous measurements at several points covering extensive areas, for extended periods of time, led to collaborative efforts involving observationalists and theorists from several institutions in several countries. Science at that time was “bottom-up” with international organizations serving to facilitate the implementation of the proposais of scientists. Progress was rapid. By the late 1980’s oceanographers had established that the ocean has its own weather, that it has a rich spectrum of variability that plays a central role in global climate fluctuations and changes. Oceanographers started monitoring the continually changing oceanic conditions by means of unattended arrays of instruments, using sophisticated, realistic computer models of the oceanic circulation to assimilate and synthesize that data, thus enabling them to provide the public, on a routine basis, with comprehensive descriptions of oceanic conditions, the counterpart of the daily weather map.

5Jacques Merle was a key participant in these important and exciting developments over the past few decades. He had the good fortune to be a member of the renowned French research organization ORSTOM which maintained oceanographic centers at several locations in the tropics, including Abidjan, Dakar, Tahiti and Noumea. When these centers were founded tropical oceanography was a curiosity. Today it is a protagonist in the story of the global climate which involves phenomena such as El Nino and global warming. In this book Merle gives an engaging account of the developments that led to this remarkable change. This is an important story because of its implications for the way we prepare for the future.

6Today oceanographers face a world very different from that of the 1960’s. The field has grown enormously; what had been a “small science” is now a “big science.” Because of concern about future global warming, on which the oceans will have a strong influence, projects organized informally by small groups of scientists have given way to large programs in which managers and bureaucrats play prominent roles. Science that used to be “bottom-up” has now become “top-down.” The competition for resources has become fierce and the sponsors of research now demand results that are of practical value. These changes occurred because of an altered social and political landscape in which scientists are active; these changes were associated with the end of the Cold War.

7Scientists need to accept the altered social and political realities, but in doing so need to maintain a balance between the two complementary and equally important goals of science — science for the sake of understanding natural phenomena, and science for the sake of useful results. In this book, Jacques Merle describes a period of exceptional progress in oceanography, a period during which unusual social and political factors allowed scientists to focus on science for the sake of science. His engaging account of the many benefits that accrue from pursuing that goal of science is a timely reminder of the need to give that goal a high priority now that the emphasis has shifted to science for practical benefits.


Professor of geoscience, Princeton University Member of the National Academy of Science-USA

© IRD Éditions, 2006

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