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Petermann Glacier Iceberg Calving
summer melt does the damage!
On 5 August 2010, the largest iceberg to calve from the Greenland Ice Sheet in recent history broke away from the Petermann Glacier, raising concerns about the glacier's stability and consequent effects on sea level.
Petermann Glacier in North Greenland is a major outlet glacier, currently draining about 6% of the Greenland Ice Sheet into the ocean. Uncertainty in predicting mass loss from the marine outlet glaciers in Greenland is one of the major limitations in forecasting future sea level change. During the past decade, many marine outlet glaciers in Greenland (and several in Antarctica) have retreated and increased their speed dramatically. These recent dynamic changes seem to coincide with oceanic and atmospheric warming, but the linking mechanisms are not well understood.
In a paper published in the latest Journal of Glaciology, researchers from the Institute for Marine and Atmospheric Research, Utrecht University, The Netherlands, and the Laboratoire de Glaciologie, Université Libre de Bruxelles, Belgium use numerical modeling to assess the impact of the large 2010 calving event on the current and future stability of Petermann Glacier, and to ascertain the glacier's interaction with various components of the climate system. Their results show that the recent break off did not result in significant glacier speed-up. If the recent calving event was an extreme example of natural variability, the glacier may recover within about 30 years.
Satellite data show seasonal variability in the flow speed of the glacier along the entire ice shelf. Project leader Dr Faezeh Nick explains that seasonal acceleration of the glacier is controlled by lubrication by water due to summer surface meltwater run off. Even though meltwater is less abundant as far north as Petermann Glacier, and despite the findings for other marine outlet glaciers, the seasonal acceleration of Petermann Glacier seems mainly to be controlled by surface melt.
Furthermore, the model shows that melt of the underside of the glacier (where it floats in a fjord) is likely to have a profound effect on the future stability of Petermann Glacier, and is the only possible cause of glacier collapse in the foreseeable future.
Further observations are essential to obtain better understanding of water temperature variability and circulation within the fjord at the front of the glacier.
Faezeh M. Nick is a post-doctoral researcher working at two institutes: the Institute for Marine and Atmospheric Research, Utrecht University, in The Netherlands, and the Laboratoire de Glaciologie, Université Libre de Bruxelles, in Belgium.
Click on the link below to see the full paper.
The response of Petermann Glacier, Greenland, to large calving events, and its future stability in the context of atmospheric and
oceanic warming
F.M. NICK, A. LUCKMAN, A. VIELI, C.J. VAN DER VEEN, D. VAN AS, R.S.W. VAN DE WAL, F. PATTYN, A.L. HUBBARD, D. FLORICIOIU
229–239