Huge chunk breaks off storied Arctic ice shelf

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TORONTO -- A 1.6 square-mile chunk has broken off Ward Hunt Ice Shelf -- the largest remaining ice shelf in the Arctic -- threatening the future of the giant frozen mass that northern explorers have used for years as the starting point for their treks.Scientists say the break, the largest on record since 2005 but still small when compared to others, is the latest indication that climate change is forcing the drastic reshaping of the Arctic coastline, where about 3,500 square miles of ice have been whittled down to less than 386 square miles over the past century, and are showing signs of decreasing further."Once you unleash this process by cracking the ice shelf in multiple spots, of course we're going to see this continuing," said Derek Mueller, a leading expert on the North who discovered the ice shelf's first major crack in 2002.Mueller was part of a team monitoring ice along the northern coast of Ellesmere Island last April that discovered deep new cracks -- 11 miles long and 131 feet wide -- on the edge of Ward Hunt Ice Shelf, a 135-square-mile mass of ice that joins tiny Ward Hunt Island to the bigger Ellesmere. The cracks indicated a split was likely coming. "It may weaken over time; it may melt away slowly, then all of a sudden you pass this threshold," Mueller said. "It's like a bar of soap. If you use the soap over and over again, it gets thinner and thinner. Then all of a sudden, it could break."Nobody knew when it would happen," he said, adding that specific conditions were required to enable it, including "offshore wind and a bit of open water in front of the ice shelf."Sami Soja, a Kingston-based surveyor on contract to Parks Canada, was working on the island last week and was one of the first to witness the breakup."We hiked up (a peak) on the island, which is probably only about seven kilometers wide, . . and you could see those big cracks along it," he said, adding that, when he hiked back to the same point a few days later, "it was like, wow, something's totally different out there."When Soja's team was airlifted off the island Sunday, they asked the pilot to fly over the ice mass so they could see the change from a better vantage point. From the air, he said, the group could see "a chunk was gone."Trudy Wohlleben, a sea-ice forecaster with the Canadian Ice Service, said the chunk could float for some time in the Beaufort Gyre -- an ice-clogged, clockwise current in the western Arctic -- and is unlikely to be an imminent danger to ships.At this point, she said her team is confident the ice mass broke off last Wednesday or Thursday.Warwick Vincent, director of Laval University's Center for Northern Studies, has had students monitoring conditions on the ice shelf for years. He called the ice break "a significant event" that the shelf has been building toward since it began gradually thinning during the 1950s. Since then, over a 40-year period, the shelf thinned from 229 feet in the early 1950s to about 115 feet in the 1990s, Dr. Vincent said. Vincent said it's important to note that the Ward Hunt ice break is "small compared to what we've seen in the past."Indeed, the largest ice break recorded in recent time was significantly larger: In 2005, the Ayles Ice Shelf, one of six in existence in Canada at the time, broke off in its entirety, rendering a 25-square-mile ice island that floated out to sea.Still, the latest break "indicates ongoing change in this very sensitive area," Vincent said. Mueller, whom Vincent calls the pre-eminent expert on Ward Hunt Ice Shelf, says he's concerned that the ice shelves will disappear completely."The take-home message for me is that these ice shelves are not regenerating," he said. "If we're looking at an indicator of whether climate is to blame, it's really the lack of regeneration that convinces me. They're breaking away so rapidly that there's no hope of regeneration," he said.(Distributed by Scripps Howard News Service, www.scrippsnews.com.)