Petermann Glacier front breakup, July-August 2008
A 29 sq. km. (11 sq. mi.) area of the Petermann Glacier in northern Greenland (80˚N, 60˚W) broke away between July 10th and by July 24th.
Petermann has a floating section 16 km (10 mi) wide and 80 km (50 mi) long, that is, 1295 sq. km (500 sq mi); the longest floating glacier in the Northern Hemisphere.
Here is an animation of the breakup.
This 2008 breakup is actually not the largest observed. Between 2001 and 2000, 86.8 sq. km (33.5 sq. mi.) broke away from the Petermann front. However, more breakup is immenent in the next year, for, a large crack has widened while moving toward the calving front.
ASTER image courtesy of Ian Howat showing Petermann Glacier crack
Here is an annual (2001-2007) animation Ian Howat made of the crack flowing toward the glacier front while widening.
If the Petermann glacier breaks up back to the upstream rift, the loss would be as much as and additional 160 sq. km (60 sq. mi); a loss of one third of the massive Petermann ice tongue.
The Petermann glacier thins from 600 m thickness at the grounding line to 70 m at the terminus, see . The crack is advancing to a point where a massive breakup seems imminent, in which case, the area of break-up would be 56-60 sq. miles (147-160 sq. km).
Addendum (25 Dec, 2008)
Petermann Glacier thins from 600-700 m at the grounding line primarilly due to basal melting  calves 0.6 km3 (Higgins, 1990). “The lower 80 km (in length) and 1300 km2 (in area) of the glacier is afloat. This makes it (by area) the largest floating glacier in the Northern Hemisphere. “…”The calving front protrudes a mere 5-10 m above sea level, reflecting the fact that the ice at the front is only 60-70 m thick.” M. Pelto, Real Climate.
(2008), Channelized bottom melting and stability of floating ice shelves, Geophys. Res. Lett., 35, L02503, doi:10.1029/2007GL031765
Higgins, A. 1990. Northern Greenland glacier velocities and calf ice production. Polar Forschung, 60, 1-23.
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