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Wednesday, August 20, 2008

Jakobshavn Glacier Retreats to New Minimum

Jakobshavn Glacier Retreats to New Minimum

MODIS image of Jakobshavn Glacier with lines indicating continued retreat.

The Jakobshavn Glacier front retreated 14 sq. km (5 sq. mi.) between 6-15 August 2008. [BLOGGER'S NOTE: Obviously, there is something wrong either with the sentence just above or with the notes on the photo. The conservative guess would be to say that the glacier has retreated 5 sq. mi. in the past year, not in just 9 days, although, on one occasion a glacier was seen to rush out at a speed of over a kilometer per hour.]

Jakobshavn Glacier is the world’s fastest continuously flowing glacier and the main outlet from the vast 1.69 million sq. km Greenland ice sheet. Jakobshavn drains 6.5% of the ice sheet, producing 35–50 cubic km of icebergs per year.

The 2008 retreat is to a position further inland than any time over the past 150 years of direct observation and likely is further back than during any time since the Holocene Thermal Maximum 4-8 thousand years before present, because the interim period ends with the Little Ice Age c. 1250 AD - 1850 AD glacier advance.

Of distinction from a retreat trend mainly at the faster southern branch of Jakobshavn Glacier since 2001, is the northern branch has retreated in the past weeks. Repeat altimeter measurements show the northern branch thinning in recent years at an accelerated rate (Ian Howat, personal communication).

Image with end of summer positions indicated. We measure interannual changes using end of summer images because glaciers reach a seasonal minimum at the end of summer.

Between 2001 and 2005, a collapse of the Jakobshavn Glacier floating tongue removed 94 sq. km (36 sq. mi.).

Additional Figures:

  • End of summer 2000-2008: small (720×540), large (1420×1080)
  • End of summer 2007-2008: small (720×540), large (1420×1080)


Page Constructed by Jason Box, Russ Benson, and David Decker, Byrd Polar Research Center.


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