CHILLING.(The Talk of the Town)(Antarctica shrinks)

I n March, 2002, NASA and the Deutsches Zentrum fur Luftund Raumfahrt, the German aerospace agency, launched a pair of satellites from the Plesetsk Cosmodrome, a former intercontinental-ballistic-missile site in northern Russia, to map changes in the earth's surface. The satellites, nicknamed Tom and Jerry, have been chasing each other around the globe ever since. Separated by a gap of approximately a hundred and thirty-seven miles, they sometimes pull apart, only to draw closer again. By monitoring their relative positions to the fantastic exactitude of one micron--less than one-fiftieth the width of a human hair--scientists can detect tiny variations in the earth's gravitational field.

Now, almost four years to the day after they were launched, Tom and Jerry have yielded a scarily significant result: Antarctica is losing ice. The rate of loss, according to researchers at the University of Colorado, in Boulder, who analyzed changes in the continent's gravitational pull, is around thirty-six cubic miles per year. (For comparison's sake, the city of Los Angeles uses about one-fifth of a cubic mile of water annually.) The finding, which was reported two weeks ago in the online version of Science, is particularly ominous, because climatologists had expected that even as the ice sheet lost mass at its edges, its over-all mass would increase, since rising temperatures would lead to more snowfall over the continent's midsection. If the loss continues, it will mean that predictions for the rise in the sea level for the coming century are seriously understated.

The news from Antarctica follows a string of similarly grim discoveries. In September, satellite measurements showed that the extent of the Arctic ice cap had shrunk to the smallest area ever recorded, prompting a prediction that the Arctic Ocean could be ice-free in summer "well before the end of this century." Around the same time, a group of British scientists reported that soils in England and Wales have been losing carbon at the rate of four million metric tons a year, a loss that is at once a symptom of warming and--as much of that carbon is released into the atmosphere--a likely cause of more. In January, researchers at NASA's Goddard Institute for Space Studies concluded that 2005 had been the hottest year on record, and, in February, a team of scientists from NASA and the University of Kansas announced that the flow of ice from glaciers in Greenland had more than doubled over the past decade. Earlier this month, the Washington Post reported that the mountain pine beetle, a pest once kept in check by winter cold, has decimated huge swaths of forest in western Canada. Officials with the Canadian Forest Service say that the beetle has crossed the Rockies and they fear that it will soon start eating its way east. "People say climate change is something for our kids to worry about," one official told the Post. "No. It's now."

In the face of such news, how does a country, i.e. the United States, justify further inaction? Certainly, there isn't much tread left in the argument that global warming is, to use Senator James Inhofe's famous formulation, a ...