Polar Oceans; The Oceans; Scientific American Presents; by Staff Editor; 2 Page(s)

The ice-covered Arctic was first recognized to be a deep basin only a century ago, and it remains today the most enigmatic ocean on the earth. Scientists are still trying to determine, for example, whether the warming that has occurred in most other parts of the planet has caused the Arctic ice pack to thin. Such a change would be worrisome, because only a few meters of ice separate the frigid Arctic atmosphere from the comparatively warm water below. A breakup of the ice would thus allow a great amount of heat from the ocean to pass into the air above, accelerating any warming trend in that far northern region.

The southern reaches of the Atlantic, Pacific and Indian oceans are often considered a single entity. This vast "Southern Ocean" encircles the Antarctic continent with two counterrotating sets of currents. Hugging Antarctica and streaming from east to west is the so-called East Wind Drift. Farther north, the eastward-directed Antarctic Circumpolar Current prevails. This strong, wide current, and the winds that drive it, made for arduous journeys from the Atlantic to the Pacific when sailors had to navigate around Cape Horn, the southern tip of South America, before the construction of the Panama Canal. (Being merely the southern parts of the Atlantic, Pacific and Indian oceans, the "Southern Ocean" has been included in the statistical summaries given on pages 8, 10 and 12.)