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It contains enough freshwater to keep the Hudson River flowing for more than two years, said Andreas Muenchow of the University of Delaware.

The drifting ice sheet is likely to remain at the heart of the global warming discussion during its journey.

While experts say it’s difficult to directly tie the giant ice island to climate change because there are so many factors that affect glaciers in the area, the unusual event coincides with worrisome signs of warming in the Arctic.

Since 1970, temperatures have risen more than 4.5 degrees (2.5 degrees C) in much of the Arctic _ much faster than the global average. In June the Arctic sea ice cover was at the lowest level for that month since records began in 1979, according to the National Oceanic and Atmospheric Administration.

The retreat of Greenland’s glaciers, which has accelerated in recent years, is one of the least understood pieces of the climate puzzle.

A team of climate scientists who visited the Petermann glacier last year, expecting it to crack then, is now planning another trip within weeks.

“We did leave behind a couple of time-lapse cameras and 11 GPS (devices). Now we are scrambling to get up there and recover the data,” said Jason Box, an expert on Greenland glaciers from the Byrd Polar Research Center at Ohio State University.

Box and two British researchers traveled to the glacier last year with Greenpeace activists who offered space aboard their ship, the Arctic Sunrise, to scientists studying climate change.

They were hoping to capture the event with cameras rolling, which would have been a powerful image just months before the Copenhagen climate talks that failed to produce a binding treaty to reduce heat-trapping gas emissions.

“It would have been nice if it had broken off last year,” said Melanie Duchin, who led that Greenpeace expedition. “I mean ice melting, it doesn’t get any simpler than that.”

Still, she finds it ironic that the Petermann breakup coincides with another catastrophe linked to fossil fuels. The Arctic Sunrise is now in the Gulf of Mexico, surveying the massive oil spill from the Deepwater Horizon blowout.

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Associated Press Writer Rob Gillies in Toronto contributed to this report.