Nearly two centuries later, it gained a new vitality as scientists made Antarctica a focus of the International Geophysical Year, 1957-58. The long and continuing process has meant confronting a staggering environmental simplicity where ''ice creates more ice, and ice defines ice. Everything else is suppressed. This is a world derived from a single substance, water, in a single crystalline state, snow, transformed into a lithosphere composed of a single mineral, ice. . . . Forms of the ice range from ice islands, bergy bits, growlers and brash, to ice rinds, ice ridges, frazil ice and vuggy ice, glaciers, ice streams and ice rumples, ice sheets, ice caps, ice domes and half a dozen categories of atmospheric ice.
Variety alone overwhelms.
Magnitude staggers the mind still more. A quarter of the ocean surface is ice-covered or host to icebergs. Mechanisms that trigger these ice ages are multiple and doubtless interacting, Mr. Pyne says. Raised ocean level, partly caused by northern glacial melt, is believed to float ever more of the western Antarctic ice sheet, unhinging its precarious coupling to the land and quickening the rate at which it calves icebergs. According to the computer model, this could cause ice streams to surge forward, no longer damped and stabilized by the immensity of the Ross Ice Shelf, and the western sheet might break apart and raft away.