Scientists pored over satellite images today of the latest section of Antarctic ice to break up -- ice that the scientists said had been solid for 10,000 years.
An "ice bridge" at the edge of the Wilkins Ice Shelf, on the Antarctic Peninsula closest to South America, broke up over the weekend. Climate scientists said it may lead to the crumbling of other ice.
"We believe the warming on the Antarctic Peninsula is related to global climate change, though the links are not entirely clear," said David Vaughan of the British Antarctic Survey.
In the last year, satellite images show that the Wilkins Ice Shelf, which was about the size of Connecticut, has lost 14 percent of its mass.
"The polar regions are the fastest warming regions on the planet," said John Holdren, a climate scientist who is now the White House science advisor.
"The interactions of polar region ice and snow with oceans and atmosphere exert powerful influences on the climate of the entire planet," he said.
Scientists say up in the Arctic, meanwhile, the earth's north polar cap is thinning as well. They said this winter it reached the fifth smallest maximum size since satellite records began in 1979. All of the record years, said NASA, have happened since 2004.
More of the Arctic polar cap is melting every summer, and less is freezing in the winter. A team from the National Snow and Ice Data Center in Boulder, Colo., said 70 percent of the northern polar cap is now made of ice that melts in summer. In the 1980s and 1990s it was 40 percent to 50 percent.
At an international meeting of climate scientists and policymakers in Washington, Secretary of State Hillary Clinton said the breakup of the ice bridge was a reminder of why the Obama administration is working on the climate issue.
"We are reminded that global warming has already had enormous effects on our planet, and we have no time to lose in tackling this crisis," she said.
"Catastrophic consequences await if we don't take action soon."
But with the global economy in trouble, politicians say it's not a good time to order expensive steps to curb the greenhouse gases -- from cars, power plants and the like -- that are believed to worsen the warming.
The one concrete action proposed by Clinton today did not have much to do with the global climate. She said the United States proposed to put limits on the size of cruise ships that take people to Antarctica.
One ship, the Liberian-registered M/S Explorer, sank off the Antarctic Peninsula in November 2007. All 100 people on board were safely rescued, but they were far from help, and passengers said it was a close call.
"The miraculousness of being in Antarctica and within six hours of a boat," said one passenger, Kay Van Horne of Denver, "remarkable, remarkable."