Context for the Recent Massive Petermann Glacier Calving Event

Abstract

On 4 August 2010, about one fifth of the floating ice tongue of Petermann Glacier (also known as “Petermann Gletscher”) in northwestern Greenland calved (Figure 1). The resulting “ice island” had an area approximately 4 times that of Manhattan Island (about 253±17 square kilometers). The ice island garnered much attention from the media, politicians, and the public, who raised concerns about downstream implications for shipping, offshore oil and gas operations, and possible connections to Arctic and global warming. Does this event signal a change in the glacier's dynamics? Or can it be characterized as part of the glacier's natural variability? Understanding the known historical context of this event allows scientists and the public to judge its significance.

Glacier dynamics over the last quarter of a century at Helheim, Kangerdlugssuaq and 14 other major Greenland outlet glaciers

“…The width of the fjord varies between 15 and 20 km, is 1100 m deep, and is separated from Hall Basin by a sill at a depth of approximately 350 m to 450 m . Ice-front positions presented here for Petermann add to the long time series presented by Falkner et al (2011) Nioghalvfjerdsbrae terminates in a floating ice shelf which flows east to a 35 km calving front and north-east to a 10-km-wide front. An overdeepened trough of 900 m exists under the ice shelf with bathymetry rising to 200 m and 600 m beneath the east and north-east fronts, respectively (Mayer et al, 2000).…”

Glacier Calving in Greenland

“…This thinning appears to have played a key role in structural weakening, possibly exacerbated by the presence of channels incised into the base of the ice tongue. The wider significance of these events is difficult to assess, and Falkner et al [58] noted that a massive ice-retreat event of a similar magnitude to that on Petermann Glacier in 2010 might have occurred during a gap in the observational record. However, there is no direct evidence that this was the case, and following another highmagnitude calving event in 2012, the glacier was about 25 km more retreated than any observed position since records began in 1876 [37].…”

Interannual changes of the floating ice shelf of Petermann Gletscher, North Greenland, from 2000 to 2012

“…While PG has experienced large calving events in the past (Falkner and others, 2011), its terminus (ice front) has now retreated further back than has been observed since the first reported measurements in 1876 (Nares, 1876). By analogy with Jakobshavn Isbrae, Greenland (Holland and others, 2008;Motyka and others, 2011), we hypothesize that the observed slow warming of Atlantic-sourced waters in Nares Strait during the last decade (Münchow and others, 2011) could lead to increased basal melting of the PG ice shelf.…”

“…1), using a range of remote-sensing ice surface and bottom measurements. Opportunistic ocean surveys of Petermann Fjord in 2009 (Johnson and others, 2011) and 2012 motivated studies to determine whether the calvings were historically unusual (Falkner and others, 2011), if they could be related to ocean variability, and if loss of this portion of the ice shelf could lead to accelerated discharge of grounded ice from PG.…”