Delaware-Sized Iceberg Clings to Shelf by 'a Thread'

A chunk of ice the size of Delaware is clinging to an Antarctic ice shelf by "a thread" that could snap at any moment and create one of the 10 largest icebergs ever recorded, researchers say. Following the collapse of the nearby Larsen A ice shelf in the Weddell Sea in 1995 and Larsen B shelf in 2002, scientists noticed a rift in Larsen C, which is more than 1,100 feet thick. The rift has been extending across the ice shelf ever since, but over two weeks in December, it stretched an additional 11 miles in length, per the BBC. As of mid-December, it measured 70 miles long, the length of a football field in width, and a third of a mile deep, and had left a 2,000-square-mile chunk of ice attached to the shelf only by a 12-mile "thread" of ice, reports the Week, via NASA.

"It's so close to calving that I think it's inevitable," says researcher Adrian Luckman. "If it doesn't go in the next few months, I'll be amazed." The break will cause Larsen C to lose more than 10% of its area, leaving it "at its most retreated position ever recorded," researchers say on a project website. They believe it will also make Larsen C less stable. "We would expect in the ensuing months to years further calving events, and maybe an eventual collapse" in years or decades, Luckman says, though other scientists aren't convinced. If the entire ice shelf were to enter the sea, global sea levels could rise by 4 inches, according to estimates. For now, though, this is "just a big geographical event," Luckman says. (Scientists are searching Antarctica for 1.5-million-year-old ice.)