A vast island of ice has broken off a glacier in Greenland: but it is just one-fifth the size of one which snapped off from Canada in 1962 and half the size of one seen in 2010.
The new monster iceberg is assessed as covering 46 square miles by professor Andreas Muenchow of the University of Delaware, which he calculates as roughly twice the size of Manhattan island. It calved from the Petermann glacier in Greenland two days ago, according to an informative release from the university, and this has been confirmed from above by satellite photos. The breakoff follows a similar but bigger event in 2010, which saw a four-Manhattan berg snap off the Petermann and float away.
Muenchow says that the local air temperature in Greenland has climbed by more than two degrees since 1987, but he doesn't think this of itself means that global warming caused the ice to break off.
“The observed warming is not proof that the diminishing ice shelf is caused by this," says the prof, "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.”
Muenchow hopes to gain more data from undersea sensors placed beneath the glacier shelf in 2009 and due to be recovered by a Canadian coastguard vessel this summer.
The Delaware uni report notes that the two recent berg breakoffs from the Petermann are small beer compared with the last big ice-island calving prior to 2010, which saw a stupendous 230-square-mile (roughly a ten-Manhattan) monster break loose from Ellesmere Island in Canada. ®