Rodolfo Del Valle was conducting research at a scientific base in Antarctica this January when his radio crackled. Colleagues at an Argentine camp on the nearby Larsen Ice Shelf rattled by nonstop ice quakes, yelled, "Rudy, something's happening, the ice shelf is breaking," recalls del Valle, director of geoscience at the Argentine Antarctic Institute. Riding in a light plane, del Valle flew over the Larsen shelf, as thick as 1,000 feet in places, and saw that it was in little pieces that "looked like polystyrene that had been broken by a little boy," he reported last week. A 40-mile crack, 30 feet wide in places, had torn the ice shelf from the Weddell Sea to the mountains (map). "I was astonished," says del Valle. "And then I cried. We know that the first step in the melting of the west Antarctic ice sheet could be the destruction of the ice shelf "
The Larsen Ice Shelf isn't what it used to be. An iceberg 23 miles wide and 48 long almost as big as Rhode Island broke off from it in early January. But the cracks are an even more ominous sign of something American researchers first predicted in 1978: that the frozen continent would be the world's canary-in-a-coal-mine, showing early signs that the climate is warming. That warming would come as gases such as carbon dioxide (from the burning of coal, gas and oil) trap heat in the atmosphere. The cracking of Antarctica is far from proof that the greenhouse has arrived, of course. The warm 1990s and crumbling ice shelves, which float on the sea but due to Antarctica's weird weather. Then again, they might not. The ice shelves, says glaciologist David Vaughan of the British Antarctic Survey, "have been around for a very, very long time"; they are now piles of ice cubes leaves no doubt that Antarctica is experiencing "regional warming." Without intact ice shelves to cool them, winds blowing over Antarctica will be warmer than usual, says geophysicist Charles Ebert of the State University of New York at Buffalo. If the winds melt even a tenth of the continent's ice, sea levels worldwide would rise 12 to 30 feet.
That prospect adds urgency to a meeting in berlin this week, where more than 100 countries will discuss the climate-change treaty. Signed at the 1992 Earth Summit, the treaty requires only that countries tote up how much greenhouse gas they emit, and prepare plans to mitigate climate change. The pact does not require emissions reductions, though it politely suggests that cutting emissions to what they were in 1990 (by 2000) would be a good idea. Delegates will consider proposals to strengthen the treaty by requiring those cuts, and perhaps deeper ones. Those proposals come from 35 small island states. The Caribbean nation Trinidad and Tobago, for one, fears that rising sea levels will turn it into the new Atlantis. If the icecubing of Antarctica means what del Valle thinks it does, there is reason to worry.