Just four short years ago, a United Nations committee of experts came to the conclusion that the polar ice caps would likely not be in danger for the next 100 years. They, apparently, were wrong. The shocking truth, says Chris Rapley, head of the British Antarctic Survey (BAS), is that the thick ice layer covering the seventh continent is, according to new measurements, melting much more rapidly than anyone had thought.

"The previous view was that the West Antarctic ice sheet would not collapse before 2100. We now have to revise that judgment. We cannot be so sanguine," Rapley told the Daily Telegraph on the occasion of a climate conference in Exeter, England earlier this month. In 2001, UN experts believed that the Antarctic was a "slumbering giant." Today, says Rapley, it is more accurate to speak of "a giant awakened."

Through new measurements in the remote regions of West Antarctica, researchers have determined that each year some 250 cubic kilometers of ice slides off the continental landmass and into the ocean. Such a huge amount of ice is enough to cover a surface measuring 500 kilometers by 500 kilometers with a layer of ice 1 meter thick.

Indeed, so much ice is being shed in West Antarctica that the region alone accounts for a rise in the global ocean level of one-fifth of a millimeter. It also means that fully 15 percent of the 2 millimeter annual rise in the ocean level is being generated by Antarctica.

Rapley said that studies done on the Antarctic peninsula, which is much easier for scientists to get to than West Antarctica, have shown that the disappearance of floating ice shelves surrounding the polar continent has functioned "much like a cork pulled out of a bottle." The flow of ice rivers from the continent into the sea has increased dramatically.

The discovery of the dramatic ice break-off in the western part of Antarctica, says Rapley, "completely opens up the debate."

Past years have seen a number of gigantic chunks of ice break off from the Antarctic's ice sheet and float away from the coast as immense icebergs. The 1,600 square kilometer chunk known as Larsen A shelf broke off in 1995. In 1998, the Wilkins shelf (1,100 square kilometers) broke off followed by a chunk of ice called the Larsen B shelf measuring 3,250 square kilometers -- almost exactly the size of the island of Maui in the Hawaiian Islands -- in 2002.

Rapley said it is not clear whether the shedding of ice is directly caused by global warming or not, but he did say that, if it were a natural event, one might expect it to be taking place in only one part of the continent instead of in all three major ice streams of the Antarctic.