July 18, 2012
Greenland Glacier Loses An Ice Island Twice The Size Of Manhattan
redOrbit Staff & Wire Reports - Your Universe Online
Andreas Muenchow, associate professor of physical ocean science and engineering in University of Delaware´s College of Earth, Ocean, and Environment, reports the calving of an island two times the size of Manhattan on July 16, 2012, in his “Icy Seas” blog.
Muenchow credits Trudy Wohleben of the Canadian Ice Service for first noticing the fracture. MODIS, the Moderate Resolution Imaging Spectroradiometer aboard NASA´s Terra and Aqua satellites, confirmed the discovery by reprocessing data taken.
Petermann Glacier is one of two large glaciers left in Greenland connecting the great Greenland ice sheet with the ocean via a floating ice shelf.
At 46 square miles (120 square km), this ice island is about half the size of the mega-calving that occurred from the same glacier two years ago. The 2010 island, also reported by Muenchow, was four times the size of Manhattan. Prior to 2010, the last time such a sizable ice island was born in the region was 50 years ago. In 1962, the Ward Hunt Ice Shelf, on the northern coast of Ellesmere Island in Nunavut, Canada, calved a 230-square-mile island.
“While the size is not as spectacular as it was in 2010, the fact that it follows so closely to the 2010 event brings the glacier´s terminus to a location where it has not been for at least 150 years,” Muenchow said in a prepared statement.
“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,” he noted.
Muenchow points out that the air around northern Greenland and Ellesmere Island has warmed by about 0.11 +/- 0.025 degrees Celsius per year since 1987.
“Northwest Greenland and northeast Canada are warming more than five times faster than the rest of the world,” Muenchow said. “But the observed warming is not proof that the diminishing ice shelf is caused by this, because air temperatures have little effect on this glacier; ocean temperatures do, and our ocean temperature time series are only five to eight years long – too short to establish a robust warming signal.”
According to the statement: “The ocean and sea ice observing array that Muenchow and his research team installed in 2003 with U.S. National Science Foundation support in Nares Strait, the deep channel between Greenland and Canada, has recorded data from 2003 to 2009.”
The Canadian Coast Guard Ship Henry Larsen is scheduled to travel to Nares Strait and Petermann Fjord later this summer to recover moorings placed by UD in 2009. This mooring data, if recovered, will provide scientists with ocean current, temperature, salinity and ice thickness data at better than hourly intervals from 2009 through 2012. The period includes the passage of the 2010 ice island directly over the instruments.
According to Muenchow, this newest ice island will follow the path of the 2010 ice island, providing a slow-moving floating taxi for polar bears, seals and other marine life until it enters Nares Strait, the deep channel between northern Greenland and Canada, where it likely will get broken up.
“This is definitely dÃ©jÃ vu,” Muenchow said. “The first large pieces of the 2010 calving arrived last summer on the shores of Newfoundland, but there are still many large pieces scattered all along eastern Canada from Lancaster Sound in the high Arctic to Labrador to the south.”