The response of Petermann Glacier, Greenland, to large calving events, and its future stability in the context of atmospheric and oceanic warming

Abstract

ABSTRACT. This study assesses the impact of a large 2010 calving event on the current and future stability of Petermann Glacier, Greenland, and ascertains the glacier's interaction with different components of the climate and ocean system. We use a numerical ice-flow model that captures the major aspects of the glacier's mass budget, the resistive forces controlling glacier flow, and includes dynamic calving. Satellite observations and model results show that the recent break-off of 25% of the floating tongue did not result in a significant glacier speed-up due to the low lateral resistance of this relatively wide and thin ice tongue. We demonstrate that seasonal speed-up at Petermann Glacier is mainly driven by meltwater lubrication rather than freeze-up conditions in the fjord. Results also show that sub-shelf ocean melt may have a profound effect on the future stability of Petermann Glacier, emphasizing the urgent need for more observations, and a better understanding of fjord temperature variability and circulation.

Future sea-level rise from Greenland’s main outlet glaciers in a warming climate

“…processes of calving, grounding line retreat and submarine melting), it has a robust treatment of grounding line migration 28 and calving 29 , and reproduces the current observed dynamical behaviour of several narrow marine outlet glaciers well 13,14,21 .…”

“…Petermann Glacier in north Greenland has been flowing steadily 11 , terminating in a relatively long (~50 km) and wide (~20 km) floating ice tongue, under which high rates of submarine melt occur 12 . The break off of two substantial icebergs in 2010 (~270 km 2 ) and July 2012 (~120 km 2 ) raised concerns about this glacier's stability, but did not cause major flow acceleration 13 Various mechanisms related to atmospheric and ocean forcing have been proposed to explain the recent behaviour of the major outlet glaciers, but large uncertainties in their relative importance remain 14,15 . A warmer ocean can melt submarine ice and thereby cause the grounding line to retreat, especially when subglacial meltwater produces more vigorous buoyancy-driven circulation 16 .…”

“…As a result of weak lateral resistance from its thin, wide floating ice tongue, the flow of Petermann Glacier seems currently insensitive to changes at the terminus. Instead, its dynamics tend to be dominated by submarine melt concentrated near the grounding line 13 .…”

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.…”

Dynamics of Greenland�s glacial fjords

“…The geometry of the glacier termini range from vertical calving fronts to expansive floating tongues (e.g. Stearns and Hamilton, 2007;Nick et al, 2012).…”