100-Square-Mile Ice Sheet Breaks Off of Arctic's Petermann Glacier | 260 Square Kilometers | One-Fourth of Its Ice Shelf | Satellite Image

http://www.bbc.co.uk/news/science-environment-10900235

7 August 2010 Last updated at 13:23 ET

Huge ice sheet breaks from Greenland glacier

A glacial bay on the western coast of Greenland - 2008 file photo Thousands of icebergs calve from Greenland's glaciers every year

A giant sheet of ice measuring 260 sq km (100 sq miles) has broken off a glacier in Greenland, according to researchers at a US university.

The block of ice separated from the Petermann Glacier, on the north-west coast of Greenland.

It is the largest Arctic iceberg to calve since 1962, said Prof Andreas Muenchow of the University of Delaware.

The ice could become frozen in place over winter or escape into the waters between Greenland and Canada.

If the iceberg moves south, it could interfere with shipping, Prof Muenchow said.

Cracks in the Petermann Glacier had been observed last year and it was expected that an iceberg would calve from it soon.

The glacier is 1,000 km (620 miles) south of the North Pole.

A researcher at the Canadian Ice Service detected the calving from Nasa satellite images taken early on Thursday, the professor said.

The images showed that Petermann Glacier lost about one-quarter of its 70km-long (43-mile) floating ice shelf.

There was enough fresh water locked up in the ice island to "keep all US public tap water flowing for 120 days," said Prof Muenchow.

He said it was not clear if the event was due to global warming.

Patrick Lockerby, a UK engineer with a background in material science, told the BBC he had predicted the calve on 22 July, posting images on the science2.0 website.

"I was watching the floating ice tongue wedged between two walls of a fjord for three quarters if its length with the last part at the outlet end wedged by sea ice. I thought once the sea ice was gone, the pressure would be too great and the tongue would calve."

He said there could be a beneficial outcome if the calving drifts to block the Nares Strait and effectively prevents the loss of more ice from the Lincoln Sea.

The first six months of 2010 have been the hottest on record globally, scientists have said.

http://news.nationalgeographic.com/news/2010/08/100806-ice-chunk-island-greenlan...

Ice Island Breaks off Greenland; Bigger Than Manhattan

New Petermann glacier collapse may be biggest in recorded history.

A satellite image taken Thursday shows the huge ice island calved from Greenland's Petermann glacier.

Courtesy of Prof. Andreas Muenchow, University of Delaware
greenland-petermann-glacier-2009-08062010.jpg

Greenland's Petermann glacier in 2009. Photograph courtesy Andreas Muenchow, University of Delaware.

Christine Dell'Amore

National Geographic News

Published August 6, 2010

An ice chunk four times the size of Manhattan has broken off of Greenland's Petermann glacier—possibly the biggest glacier collapse in recorded history, scientists announced Friday (Greenland map).

The so-called "ice island" covers a hundred square miles (260 square kilometers) and holds enough water to keep U.S. public tap water flowing for 120 days, according to Andreas Muenchow, a physical ocean scientist and engineer at the University of Delaware.

As a result of the collapse, Petermann glacier—located about 620 miles (1,000 kilometers) south of the North Pole—lost about a quarter of its 43-mile-long (70-kilometer-long) floating ice shelf, satellites images taken Thursday show.

The new Greenland ice island is at least the second largest known glacial breakaway, Muenchow said. Another colossal ice chunk broke off of Petermann glacier in 1962, but it's not known whether that ice island was bigger than the new one, Muenchow said.

Like many glaciers, Petermann glacier has been disintegrating (picture) over the last couple years, he said.

(Related: "Not So Fast: Greenland Ice Melting, But Slower Than Thought.")

Regine Hock, a glacial geophysicist at the University of Alaska Fairbanks, said the breakup of ice shelves is "a normal process that happens all the time." (See a photo of an ice shelf collapse in Antarctica.)

But such a "huge, huge piece of ice ... is very unusual," Hock said.

Because coastal glaciers are accelerating as they slide out to sea in many other places, she said, "it's something to watch to look at the cause—to see if it is an indicator or sign of something happening."

http://www.examiner.com/x-3122-Chicago

Huge iceberg breaks off from Greenland
August 6, 9:40 PMChicago International Travel ExaminerDennis D. Jacobs
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The Petermann Glacier in Greenland

Scientists Jason Box of Ohio State University's Byrd Polar Research Center and polar expedition expert Eric Philips, both members of the Greenpeace Arctic Impacts tour, assisted by experts in ice logistics, set up one of a series of time-lapse cameras surveying the 16km wide Petermann Glacier, in northwest Greenland on July 29, 2009. The Greenpeace ship Arctic Sunrise arrived in the area to carry out several weeks of scientific research into the impact of climate change, and to bear witness to the glacier's disintegration. (NICK COBBING/AFP/Getty Images)

A giant iceberg with a surface area of 100 square miles has broken off the Petermann Glacier on Greenland’s northwest coast.

Thousands of icebergs are created each year by Greenland’s glaciers, but this is the largest since 1962, according to Professor Andreas Muenchow of the University of Delaware.

“In the early morning hours of August 5, 2010, an ice island four times the size of Manhattan was born in northern Greenland,” Muenchow said.

Muenchow is very familiar with the area because he conducts research in the Nares Strait between Canada and Greenland, supported by the National Science Foundation.

He said the iceberg could become frozen in place or it could drift south in the strait and threaten shipping channels.

“In Nares Strait, the ice island will encounter real islands that are all much smaller in size,” Muenchow said. “The newly born ice-island may become land-fast, block the channel, or it may break into smaller pieces as it is propelled south by the prevailing ocean currents. From there, it will likely follow along the coasts of Baffin Island and Labrador, to reach the Atlantic within the next two years.”

To give you an idea of just how big the iceberg is, Muenchow said it contains enough fresh water to keep the Hudson River flowing for two years. If that doesn’t help give you a mental image, try this: Muenchow said the iceberg contains enough water to provide all of the tap water in the United States for 120 days.

Trudy Wohlleben of the Canadian Ice Service discovered the new ‘island’ Thursday after studying NASA satellite images.

Some tour companies offer trips to Greenland’s ice fjords. Some depart from Greenland’s capital, Nuuk (Godthab).

The entire country (part of the Kingdom of Denmark) has a population of less than 60,000, so there are not a lot of services. Getting to Greenland from Chicago is also tricky. Nearly all international flights to the country depart from Copenhagen or Iceland.-International-Travel-Examiner~y2010m8d6-Huge-iceberg-breaks-off-from-Greenland

http://image3.examiner.com/images/blog/replicate/EXID3122/images/Greenland.jpg

http://voices.washingtonpost.com/capitalweathergang/2010/08/massive_iceberg_brea...

NASA MODIS image from Aug. 5, 2010, shows a large chunk of ice has broken away from Greenland's Petermann Glacier (iceberg is just to the right of center). Credit: NASA

NASA's MODIS satellite sensor, which has a history of providing breathtaking shots of our planet, was at it again yesterday. A large -- approximately 97-square-mile -- chunk of ice broke away from the Petermann Glacier in northern Greenland. This new ice island (as seen in the image above just to the right of center) is the largest iceberg formed in the Arctic since 1962, according to a University of Delaware news release. It's about 40-percent larger than the District of Columbia.

Icebergs calving off of Greenland's glaciers are nothing new. In fact, the Canadian Ice Service and the U.S. Coast Guard's International Ice Patrol estimate that anywhere between 10,000 and 40,000 icebergs calve from the glaciers of western Greenland in a given year.

What is unusual, however, is the size of this new iceberg, which is more typical of Antarctic than Arctic waters.

The National Ice Center in Suitland, Md., tracks a number of massive icebergs in the oceans surrounding Antarctica, some of which are truly monsters. One, known as D-15, is a little larger than the state of Rhode Island, and 33 are currently being tracked that are more than 10 nautical miles long on one axis.

Most Arctic icebergs are on the order of hundreds of meters long or less. Typically once every few years a larger one, miles long, will break off. Though such occurrences have become more frequent in recent years, as detailed in a news article last month:

The Canadian Ice Service, a federal agency that monitors ice hazards in the Northwest Passage and other summer shipping routes in northern Canadian waters, issued alerts last year about another massive "ice island" from Greenland -a 29-square-kilometre monolith that broke away in 2008 from the Petermann Glacier on the island's northwest coast -as it floated south toward Canada's Arctic shores.

Officials were concerned at the time about the potential risk to cruise and cargo ships, but the Petermann Ice Island eventually eroded and broke into smaller pieces along the coast of Baffin Island.

The collapse of several Arctic ice shelves in recent years has kept the Canadian Ice Service on alert for possible threats to ships and oil exploration activity.

In 2005, a 66-square-kilometre chunk of the Ayles Ice Shelf on Ellesmere Island's northern coast broke free and began drifting south. Federal scientists kept a watch on the resulting Ayles Ice Island as it tracked a worrisome route toward the Beaufort Sea.

But in August 2007, the five-by-15-kilometre slab turned down a dead-end channel between Meighen and Axel Heiberg islands, where it was expected to slowly break up over years and become an anonymous part of the Arctic pack ice.

The Petermann Glacier has been in the news as recently as 2008 when a smaller, though still massive piece of it broke free. The most recent calving is also a bit out of the ordinary when compared to other Greenland glaciers such as the Jakobshavn , which is believed to be the source of the iceberg that sank the Titanic, and Helheim. The Jakobshavn had a noteworthy melting event earlier this summer. (See this RealClimate article for a technical look at the dynamics of glacier retreat.)

So, what will become of this latest iceberg? Chances are that the majority of the iceberg will remain inside its fjord and become frozen in place this fall during the annual freeze up. Still, a large number of smaller icebergs are likely to break off from it and some of these should make it out into the Nares Strait, and from there be swept along with the currents into the northern portions of Baffin Bay.

See CWG's Andrew Freedman's recent column for more on glacial melt in Greenland and possible implications for global sea level rise.

The author, Capital Weather Gang's Brian Jackson, is a physical scientist at the National Ice Center, which is operated by the U.S. Navy, the National Oceanic and Atmospheric Administration, and the U.S. Coast Guard. Its mission is to provide snow and ice products and services to meet the nation's strategic, operations and tactical requirements.

By Brian Jackson | August 6, 2010; 2:15 PM ET

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