Petermann Glacier before-after-photos 2010-2011
From Byrd Polar Research Center - Research Wiki
To be released Wednesday, 31 August, 2011
With joint support from the US National Science Foundation and the UK NERC, during late July, 2011, a helicopter charter brought Alun Hubbard of Aberystwyth University, Wales into and out of far northwest Greenland. Jason Box stayed behind to attend urgent family matters. The purpose of the "Peter-mission" was to gather data from time lapse cameras and GPS set up July-August 2009 with the assistance of Greenpeace.
The sensors were set in anticipation of a large ice area detachment that occurred by 5 August, 2010.
The helicopter charter's last standard airport leg flew from Qaanaaq, Greenland, the northernmost non-military permanent settlement in the world, to Petermann. The round trip would be impossible without the refuel depot north set in northern Kane Basin. The helicopter trip spanned 5 days (24 - 29 July, 2011). Fly time was ~10 hours in total roundtrip from Qaanaaq.
Alun Hubbard: "Although I knew what to expect in terms of ice loss from satellite imagery, I was still completely unprepared for the gob-smacking scale of the breakup, which rendered me speechless." ... "What the breakup means in terms of inland ice acceleration and draw-down of the ice sheet remains to be seen, but will be revealed by the GPS data recovered, which we are now processing at Aberystwyth."
The 2011 site visit enabled taking photos to pair with photos taken during the 2009 field campaign. To the right of this web page are 3 image pairs (6 photos) edited by Jason that document the enormous ice area changes in Petermann fjord.
Jason combined the photo pairs into animations that either fade from one image to the other or flicker back and forth. Click below. You will get a more fluid animation after the first loading because the file sizes are large (>50 Mb)...
3. view from NE; fade
In response to the question: How abnormal is this event? Jason notes: "The August 2010 ice calving at Petermann is the largest in the observational record for Greenland" Falkner et al. (2011) scoured the observations and found no evidence of an event this large in scattered observations since 1876. Johannessen et al. (2011) identified the next largest observed Petermann calving event ocurring in 1991, being 58% as large as the 2010 event.
In an December 2010 AGU presentation abstract here, Jason Box concluded that of 38 glacier surveyed, it was only at the 6 glaciers with ice shelves* that a significant statistical link between land and sea surface temperatures and area change was evident. The physical reasoning why ice shelves respond to land and sea surface temperature change is that ice shelves are constrained to near sea-level, where temperature variations are most influential to surface melting. The surface slope of ice shelves is ~0. Glaciers climb within a few km (steeply) into colder parts of the atmosphere where surface melt rates decrease quickly. Water ponding on the surface, being much darker than a bare ice surface, concentrates solar energy, enhancing melt rates. A water filled depression, acting under gravity, has unlimited capacity to hydraulically jack through cracks in the glacier, provided it is kept filled with water. During the 24 h Arctic summer, the condition of unlimited water supply can be maintained on a glacier for weeks on end. Other factors such as tidal flexure and wind stress can be the straw that breaks the glaciers back.
(*) ice shelves: Petermann; Zachariae; Nioghalvfjerdsbrae/79; Ostenfeld; Jakobshavn; and Ryder
Works Cited - Falkner K.K., A.M. Münchow, J.E. Box, T. Wohlleben, H.L. Johnson, P. Gudmandsen, R. Samelson1, L. Copland, K. Steffen, E. Rignot and A. K. Higgins, (2011), Context for the Recent Massive Petermann Glacier Calving Event, Eos Trans. AGU, 92(14), doi:10.1029/2011EO140001.
- Johannessen, O. M., Babiker, M., and Miles, M. W.: Petermann Glacier, North Greenland: massive calving in 2010 and the past half century, The Cryosphere Discuss., 5, 169-181, doi:10.5194/tcd-5-169-2011, 2011.
A 22 Aug, 2011 publication documents the Petermann and other Greenland glacier changes...
Box, J.E. and D.T. Decker, 2011: Analysis of Greenland marine-terminating glacier area changes: 2000-2010, Annals of Glaciology, 52(59) 91-98.
The study uses optical satellite images to measure area changes at 39 of the widest Greenland glaciers in the most recent 11 years; between 2000 and 2010. During this decade, these glaciers collectively lost an area of 1535 sq. km (592.6 sq. mi). Main points of the paper include:
1. The largest annual area change for a single glacier was extreme compared with the others, where Petermann Glacier retreated 13 km by calving an ice island of 290 sq. km (112 sq. mi) between 3 and 5 August 2010.
2. While the 4x Manhattan Is. sized Petermann glacier ice shelf loss was extremely large, it is part of a larger pattern of ice area loss concentrated in north Greenland. See Figure 2 of the publication.
3. ~8/10 of the area change in northern Greenland
4. A very consistent and substantial ice area loss (121 sq km or 46.7 sq. mi per year) is found. The rates of cumulative area change very well represented by linear fits, R = -0.98 and R = -0.99
5. The count of glaciers retreating is twice that advancing.
6. The retreat area 9x gain area
7. There are other major ‘losers’ than the extreme loss at Petermann, such as Humboldt, Zachariae, Jakobshavn, more here.
8. For ice shelves, there has been no year since 2000 with a collective area gain.
This paper was made public 22 August, 2011. Search for Box and download from here.
The area change assessments are made by the diligent work of David Decker, staff at Byrd Polar Research Center.
There is more to the story of the 2011 Petermann Glacier field work. It is summarized here.
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