Peterman ice shelf calves another massive ice island
By Summit Voice
SUMMIT COUNTY — The University of Delaware is reporting that an ice island nearly twice the size of Manhattan has broken free of Greenland’s massive Peterman Glacier, which connects the Greenland ice sheet with the ocean via a floating ice shelf.
The calving was reported July 16 by University of Delaware professor Andreas Muenchow in his Icy Seas” blog. Muenchow credited Trudy Wohleben of the Canadian Ice Service for first noticing the fracture, subsequently confirmed by one of NASA’s Earth-watch satellites.
The same glacier spawned an iceberg nearly twice as big in 2010, which cut the size of the floating ice shelf by about 25 percent. The latest calving event puts the terminus of the glacier in a location where it hasn’t been for at least 150 years, according to Muenchow.
The latest iceberg is about 46 square miles. 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.
“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, explaining that the air temperatures around northern Greenland and Ellesmere Island has warmed by about .10 degrees Celsius per year since 1987.
The region is warming about five times faster than the rest of the world, but as yet, there’s no clear link between the warming and the disintegration of the ice shelf. Air temperatures have little effect on the ice overall. Ocean temps are much more important, but the data for ocean temps in the region is incomplete Muenchow said.
Working with the National Science Foundation, Muenchow has positioned an array of equipment in the Nares Strait to get more data from the area. The Nares Strait is a deep-water channel between Greenland and Canada.
When the buoys are retrieved later this summer, the data will give more detailed information on ocean currents, temperature, salinity and ice thickness at better than hourly intervals from 2009 through 2012. The period includes the passage of the 2010 ice island directly over the instruments.
Muenchow said 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, where it likely will get broken up.