Petermann Glacier

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NASA satellite image.

Petermann Glacier is a large glacier located in North-West Greenland to the east of Nares Strait. It connects the Greenland ice sheet to the Arctic Ocean near 81 degrees north latitude. The tidewater glacier consists of a 70 km (43 mi) long and 15 km (9.3 mi) wide floating ice tongue whose thickness changes from about 600 m (2,000 ft) at its grounding line to about 30–80 metres (98–262 ft) at its front.[1] Rough mass balance estimates using these scales suggest that about 80% of its mass is lost as basal meltwater, yet little oceanographic data are available to connect Petermann Glacier to its fjord and adjacent Nares Strait. Even the sill depth and location is largely unknown as modern soundings of the fjord are still lacking.[2]

Satellite Imagery[edit]

Natural-colour satellite image of the ice island that calved off the glacier on August 5, 2010.

A series of satellite images from 2002 through 2009 illustrate that the terminus of the glacier has advanced towards the ocean, however, several lateral rifts have developed also. The distance of this rifts or cracks back from the terminus has diminished for this time period also and may serve as a precursor to natural ice calving from Petermann Glacier.[3] A large chunk estimated to be 100 square miles (260 km2) calved off the glacier[4] in August, 2010. The Danish Meteorological Institutes maintains an archive of imagery of Petermann Glacier and adjacent coastal areas of Greenland [5][6] from both European and US satellites and sensors such as Envisat, MODIS, and AVHRR.

Data from Operation IceBridge show a 750 km long subglacial canyon running from the center of the island northward to the fjord of the Petermann Glacier. Dubbed "Greenland Grand Canyon" by media, the canyon is likely to have influenced basal water flow from the ice sheet interior to the margin. The canyon predates ice sheet inception and has influenced basal hydrology in Greenland over past glacial cycles.[7]

Ship-Based Science Explorations 2003-2009[edit]

The US Coast Guard icebreaker "USCGC Healy" entered the fjord on August 11, 2003 to survey bottom topography, ocean currents, and ocean chemistry as part of a larger program funded by the US National Science Foundation to better understand rates and mechanism by which Arctic sources of fresh water may impact the climate states of the North Atlantic. The program was continued as part of the Canadian International Polar Year projects when the CCGS Henry Larsen entered the fjord in 2007 and 2009.

In 2009, scientists aboard the Greenpeace ship Arctic Sunrise conducted multi-disciplinary measurements at Petermann glacier to document the anticipated detachment of a large area of the glacier to obtain insight into glacier dynamics and to highlight glacier response to ongoing Arctic climate warming ahead of the Copenhagen summit.[8]

Ice loss[edit]

Time-lapse imagery from July 9 to Sept. 13 2012 shows an ice island calve from Petermann Glacier and pass through Nares Strait.

In August 2010, a giant iceberg measuring 260 square kilometres (100 sq mi) broke off from the floating portion of Petermann Glacier reducing its area and volume by about 25% and 10%, respectively. Researchers from the Canadian Ice Service located the calving from NASA satellite images taken on August 5; Patrick Lockerby re-posted cropped NASA images with interpretations on the internet the same day. It was the largest Arctic iceberg to calve since 1962, however, it is unclear whether the event was related to global warming or not.[9] The Select Committee on Energy Independence and Global Warming of the US House of Representatives held hearings on Petermann Glacier and the Greenland icesheet within days of the 2010 break-up.[10]

The National Ice Center named the new iceberg, the Petermann Ice Island (2010)[11] to differentiate it from a similar calving event two years earlier which produced Petermann Ice Island (2008). That island was tracked by the Canadian Ice Service for over a year as it travelled out into Nares Strait and south through Baffin Bay before losing contact with the remnants in Frobisher Bay in July 2009.[12]

On July 15/16 2012, a 130-square-kilometre (50 sq mi) piece (about twice the area of Manhattan), calved from the northern tip of the glacier. A long crack at the site had been observed by NASA satellites for several years prior to the split.[13]

References[edit]

  1. ^ Rignot, E. and K. Steffen, 2008: Channelized bottom melting and stability of floating ice shelves, Geophys. Res. Let., 35, L02,503.
  2. ^ Johnson, H.L., A. Muenchow, K.K. Falkner, and H. Melling, 2010: Ocean Circulation and properties in Petermann Fjord, Greenland, Journal of Geophysical Research, doi:10.1029/2010JC006519.
  3. ^ "What links the retreat of Jakobshavn Isbrae, Wilkins Ice Shelf and the Petermann Glacier?". RealClimate. Retrieved 2012-07-18. 
  4. ^ McNally, Jess (August 6, 2010). "Enormous Ice Block Breaks Off Greenland Glacier". Wired. 
  5. ^ "COI | Centre for Ocean and Ice | Danmarks Meteorologiske Institut". Ocean.dmi.dk. 2009-06-21. Retrieved 2012-07-18. 
  6. ^ Pictures before and after
  7. ^ "Greenland's Mega Canyon (narrated video)". NASA. 2013-08-29. Retrieved 2013-08-30. 
  8. ^ "Arctic Impacts". Greenpeace. June and July 2009. Retrieved 2009-07-17.  Check date values in: |date= (help)
  9. ^ Huge ice sheet breaks from Greenland glacier
  10. ^ US House of Representatives Aug.-10, 2010 Briefing on "The Greenland ice sheet: Global Warming's impact in Arctic regions"
  11. ^ The National Ice Center Press Release
  12. ^ Canadian Ice Service information page on the Petermann Ice Island (2008)
  13. ^ The Associated Press. "Iceberg twice the size of Manhattan breaks off Greenland glacier - Technology & Science - CBC News". Cbc.ca. Retrieved 2012-07-18. 

External links[edit]

Coordinates: 80°45′N 60°45′W / 80.750°N 60.750°W / 80.750; -60.750