NewsSeptember 1, 2011

Huge Chunk of a Greenland Glacier Set to Break Off - Again

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Andrew Freedman

By Andrew Freedman

In August 2010, a section of ice about four times the size of Manhattan broke off the Petermann Glacier in northern Greenland. This was the largest glacial calving event ever seen in Greenland, according to polar researcher Jason Box of the Byrd Polar Research Center at Ohio State University.

Now, Box and other researchers are warning that another massive chunk of ice is close to breaking off from the same glacier, speeding the Petermann’s already rapid slide into the sea. Ice is melting all over the planet, but it’s what happens to land ice, such as the vast Greenland and Antarctic ice sheets, that will largely determine how high sea levels rise during the coming decades.

In recent years, that fate has started to look increasingly dire: new research shows that glacial melting has sped up lately, a development that Box calls a telltale sign of global warming.

Box and his colleague Alun Hubbard of Aberystwyth University in Wales have released high resolution before-and-after images that reveal the scale of the ice loss at Petermann, with open water interspersed among scattered pieces of ice where solid ice used to be.

Before-and-after photos of the Petermann Glacier's ice shelf in 2009 compared to 2011.
More images are available on their website. Credit: Jason Box and Alun Hubbard.

Even though they knew about the breakup event, Hubbard said it was nevertheless a shock to see firsthand. “I was still unprepared for the impact I felt of the scale of the breakup which rendered me speechless,” Hubbard said.

As Climate Central detailed last year, Box and his colleagues had hoped to capture the August breakup event using high-resolution time-lapse cameras. But, this was not to be. A team of researchers that had volunteered to service the cameras in 2010 failed to reset the timers on one of the cameras, causing its memory card to fill up too quickly to capture the breakup. To make matters worse, the backup camera was blown over by the wind.

Just getting to the field site was extremely arduous, since the front of Petermann is a 260 mile helicopter flight from Qaanaaq, Greenland, which is the northernmost non-military settlement in the world.

While retrieving the cameras earlier this year, Hubbard walked an estimated 80 miles on the ice in search of GPS units used for tracking ice movement, in order to save precious helicopter fuel. Box noted that Hubbard is a Welsh mountaineer.

Box recently coauthored a study in the journal Annals of Glaciology that found that 39 of Greenland’s widest glaciers collectively lost an area of nearly 593 square miles between 2000 and 2010, with the greatest loss recorded at Petermann. The study found that the vast majority of the losses in area have occurred in northern Greenland, which matches with climate data that shows the climate is warming more significantly in that region. Greenland’s widest glaciers, including the 68-mile-wide Humbolt Glacier, are found in the north. “There’s more [ice] to lose in the north,” Box says.

Glaciers can lose area and volume for a variety of reasons. In the case of the Petermann Glacier and others whose ice shelves extend into the water, evidence indicates that warming waters are helping to melt the shelves from below. In addition, since ice shelves lie at sea level, they are more susceptible to melting from warm air temperatures than glaciers that terminate at higher altitudes, where temperatures tend to be cooler.

Box says melting ice at the front of a glacier speeds the ice movement into the sea. “…the loss of the ice at the front is very important in terms of reducing the back resistance, the flow resistance is being reduced on these glaciers by losing ice at the front so they will accelerate in the future,” he says.

Matching this expectation, Box says there is currently another “enormous crack or rift” developing on the Petermann Glacier, and the next piece is liable to break off at any time during the remaining days of this melt season or next year. “In northern Greenland I think we’re just starting to see the… glaciers just start to react to the strong warming that has taken place,” he says.

Although the Arctic seems far-removed from everyday developments in the United States, Box notes that what happens there will eventually affect those in lower latitudes. “People should care because climate change in the Far North is occurring faster than down where we live… and what happens in the Far North affects us via sea level.” He noted that Hurricane Irene may have caused more damage via coastal flooding since sea levels have already risen by about a foot along the East Coast during the past century.

“Ice is nature’s thermometer, and if it melts away, we know that something has occurred. Ice doesn’t pay attention to politics, it reacts to temperature and that’s it.”