July 18th, 2012 by James Ayre
An iceberg nearly twice the size of Manhattan has just broken away from the floating end of Petermann Glacier in Greenland. This event was predicted last autumn by researchers.
The massive floating ice island is 46 square miles, and just separated from the terminus of one of Greenland’s largest glaciers.
“The Petermann Glacier last birthed — or ‘calved’ — a massive iceberg two years ago, in August 2010. The iceberg that broke off and floated away was nearly four times the size of Manhattan, and one of the largest ever recorded in Greenland.”
Even though the new iceberg isn’t as huge as its 2010 predecessor, its separation has moved the front end of Petermann Glacier farther inland than it has been in 150 years, Andreas Muenchow, an associate professor of physical ocean science and engineering at the University of Delaware, said in a statement.
“Jason Box, a scientist with Ohio State University’s Byrd Polar Research Center, has also been monitoring the Petermann Glacier and in September 2011 said that a growing crack likely would sever the glacier once warmer weather took hold during the summer months.”
“Muenchow said that the newest ice island broke away on Monday morning (July 16).”
Although the birth of icebergs is, itself, a natural process, when the process is put into overdrive there will be consequences.
“The floating ends of glaciers, known as ice shelves, act as doorstops. When these ice shelves suddenly splinter and weaken or even collapse entirely, as has been observed in Antarctica, the glaciers that feed them speed up, dumping more ice into the ocean and raising global sea levels.”
“The Greenland ice sheet as a whole is shrinking, melting and reducing in size as the result of globally changing air and ocean temperatures and associated changes in circulation patterns in both the ocean and atmosphere,” Muenchow said.
Some background information on Petermann Glacier:
“Petermann Glacier is a large glacier located in North-West Greenland to the east of Nares Strait. It connects the Greenland ice sheet to the Arctic Ocean near 81 degrees north latitude. The tidewater glacier consists of a 70 km (43 mi) long and 15 km (9.3 mi) wide floating ice tongue whose thickness changes from about 600 m (2,000 ft) at its grounding line to about 30–80 metres (98–260 ft) at its front. Rough mass balance estimates using these scales suggest that about 80% of its mass is lost as basal meltwater, yet little oceanographic data are available to connect Petermann Glacier to its fjord and adjacent Nares Strait. Even the sill depth and location is largely unknown as modern soundings of the fjord are still lacking.”
“In August 2010, a giant sheet of ice measuring 260 square kilometres (100 sq mi) broke off from the Petermann Glacier reducing its area and volume by about 25% and 10%, respectively. Researchers from the Canadian Ice Service located the calving from NASA satellite images taken on August 5th; Patrick Lockerby re-posted cropped NASA images with interpretations on the internet the same day. It was largest Arctic iceberg to calve since 1962.”
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