U.S. Secretary of State Hillary Clinton on Monday called for enhanced protection of the Earth's polar regions and tighter controls on cruise ships and tourists in Antarctica to prevent further environmental damage to the fragile region.

The ice shelf in Antarctica [chinanews.com.cn]

Opening the 32nd Antarctic Treaty Consultative Meetings to be held in Baltimore, Maryland, on April 6-17, Clinton said the recent collapse of an Antarctic ice bridge shows that the poles are gravely threatened by climate change and human activity.

"With the collapse of an ice bridge that holds in place the Wilkins Ice Shelf, 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," Clinton said.

One ice shelf in Antarctica has completely disappeared and another two have lost massive sections, as glaciers there are melting more rapidly than previously known due to global warming, according to two separate studies on Friday.

The U.S. Geological Survey (USGS) said in a report prepared in collaboration with the British Antarctic Survey that the Wordie Ice Shelf, which has been retreating in the past 40 years, is completely gone. Moreover, the northern part of the Larsen Ice Shelf no longer exists, the USGS said, adding that more than 8,500 sq km have broken off from the Larsen Ice Shelf since 1986.

In a second study, images captured by Envisat, the European Space Agency's (ESA) environmental satellite, show that the Wilkins Ice Shelf is at risk of partly breaking away from the Antarctic Peninsula as the ice bridge that connects it to Charcot and Latady Islands looks set to collapse.

New rifts are quickly expanding along the ice bridge, resulting in a large block of ice breaking away, the ESA said in a statement, adding that last year saw the ice loss of about 1800 sq km from Wilkins, or about 14 percent of its size.

In another study published in the journal Geophysical Letters, the U.S. National Oceanic and Atmospheric Administration reported that ice is melting much more rapidly than expected in the Arctic as well, based on new computer analyses and recent ice measurements.

Clinton also formally announced that at the treaty conference the United States would be proposing mandatory limits on the size of Antarctic cruise ships and the number of passengers they bring ashore.

"We have submitted a resolution that would place limits on landings from ships carrying large number of tourists. We have also proposed new requirements for lifeboats on tour ships to make sure they can keep passengers alive until rescue comes."

Tourism to the Antarctic region has increased five-fold since the early 1990s as tens of thousands of people cruise during the Southern Hemisphere's summer to see shrinking icebergs and wildlife.

(Xinhua News Agency April 7, 2009)