Antarctic Meltdown; March 1993; Scientific American Magazine; by John Horgan; 5 Page(s)

Flying toward the South Pole in a C-130 military transport, one might not think of the vast ice sheet below as an ephemeral phenomenon. The ice smothers virtually the entire Antarctic, an area as large as the U.S. and Mexico combined. Toward the center of the continent, ranges of towering mountains diminish and finally disappear below ice several kilometers thick. The ice cap is so massive that it compresses the underlying rock; if some Titan pried the ice away, the earth would spring up more than 100 meters.

Yet signs of flux are visible, especially on the perimeter of the continent. Standing on a peak of Ross Island, home to McMurdo Station, Antarctica's largest research base, one can see mighty ice streams and glaciers descending to the sea, where they shed mass by calving icebergs and by melting. (An ice stream flows through stationary or slowermoving ice, whereas a glacier is bounded on each side by rock.) Occasional flurries of snow provide a reminder that precipitation is the ultimate source of all Antarctica's ice.