Greenpeace is recording the breakup of the Petermann glacier, one of Greenland"s largest.© www.greenpeace.org
The largest floating glacier in the northern hemisphere is cracking again. Scientists are expecting five billion tons of ice to break away from the Petermann glacier this summer—a piece about the size of Manhattan. In fact, the ice chunk contains enough water to supply New York City for more than two years.
A team of independent scientists spent the past two weeks studying the 50-mile long, 10-mile wide "ice tounge" on the northwest coast of Greenland. Aboard the Artic Sunrise, a Greenpeace ship, they took photographs and footage of the massive glacier.
The Petermann glacier lost a one-billion-ton chunk of ice from the same shelf last year, and about a 1.9 square-mile piece on July 13. Scientists are using new technology to study the melting glacier that allows them to estimate when future cracks and breaks will occur. With the aid of time-lapse cameras, GPS units and oceanographic equipment, the researchers are documenting the accelerating rate of glacier melting. They say the ice is melting at a faster rate than originally predicted.
"The loss of ice from glaciers like Petermann has been likened to pulling a cork from a bottle," Dr. Alun Hubbard, a glaciologist, said. "Their removal hastens the flow of Greenland’s ice sheet to the ocean, contributing to sea level rise."
The Petermann glacier is part of a network of glaciers that hold back the Greenland ice sheet. If that ice sheet collapses, scientists say, water would be released at an incredibly high rate. Melanie Duchin, the Greenpeace expedition leader, says, "Greenland’s glaciers are melting much faster than scientists have been predicting indicating the urgent need for real and meaningful action at the upcoming climate meeting in Copenhagen in December."