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Manhattan-Size Ice Island Cracks in Half

John Roach
for National Geographic News
October 3, 2007
 
A Manhattan-size Arctic ice shelf that broke away from Canada's Ellesmere Island in August 2005 has broken in half, satellite pictures reveal.

Aided by record low Arctic sea ice levels this past summer, the Ayles Ice Island had drifted unusually far south.

Scientists had expected the originally 26-square-mile (66-square-kilometer) iceberg to remain in the Arctic Ocean, rotating with the currents, as other ice islands have done in the past.

"What's different this year is it has made its way down into Queen Elizabeth Islands, out of the Arctic Ocean," said Luke Copland, a geographer at the University of Ottawa in Ontario, Canada. (See Canada map.)

"What's helped it to do that was the very low sea ice," he added.

In the Queen Elizabeth Islands warmer temperatures likely contributed to the breakup, according to Copland.

Open Water

Scientists with the National Snow and Ice Data Center in Boulder, Colorado, reported on Monday that Arctic sea ice extent this September reached a record low of 1.65 million square miles (4.28 million square kilometers).

That's 23 percent lower than the previous record set in September 2005.

Sea ice normally blocks passage from the Arctic Ocean to the Queen Elizabeth Islands, but this summer's melt cleared the way for the Ayles Ice Island.

"That process allows it to get further south where, of course, it's warmer," Copland said. "And that's going to be a factor allowing it to break apart."

In the relatively warmer southern climes, the Ayles Ice Island split in two on September 4, satellite images show.

The larger chunk measures about five by three miles (eight by five kilometers). The smaller one is about three by three miles (five by five kilometers). As of May the ice was 148 feet (45 meters) thick.

Copland expects the ice chunks to completely melt within a decade or so, given their new southern position. Previous ice islands in the Arctic Ocean have stuck around for upward of half a century.

Collision Averted

In summer 2006 the ice island was drifting rapidly to the west, raising fears that it would head into the Beaufort Sea and collide with an oil rig there.

But the chunk's southern foray appears to have averted the crisis: The Queen Elizabeth Islands are mostly uninhabited and lack industrial infrastructure.

"The risk [of collision] has actually been reduced," Copland said.

Researchers are continuing to monitor the ice chunks.

Since their breakup, the two pieces have traveled at different speeds and followed their own courses through the narrow passages in the remote island chain.

"They'll either get stuck within the islands, or there is a chance they can make their way through these gaps in these islands and then actually head to the North Atlantic," Copland said.

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