Unprecedented Retreat in a 50-Year Observational Record for Petermann Glacier, North Greenland

Abstract

Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a∼270 km² calving event that was observed from satellite sensors in August 2010, shortening the ice tongue by∼27 km. Further, in July 2012, another 10 km was lost through calving. In order to understand these events in perspective, here the authors perform a long-term data analysis of Petermann Glacier calving-front variability and ice velocity for each year in the 1990s-2000s, supplemented by available observations from the previous three decades. Five major (on the order of 100 km²) calving events are identified, with∼153 km² calved from 1959 to 1961,∼168 km² in 1991,∼71 km² in 2001,∼270 km² in 2010, and∼130 km² in 2012-as well as∼31 km² calved in 2008. The increased frequency of major calving events in recent years has left the front terminus position retreated nearly 25 km beyond the range of observed in previous decades. In contrast, stable ice-dynamics are suggested from ice-velocity measurements made each year between 1993-2012, which are on average 1063 m yr-1, with limited interannual variability and no significant trend; moreover, there is no apparent relationship between ice-velocity variability and calving events. The degree to which the massive calving events in 2010 and 2012 represent natural episodic variability or a response to atmospheric and/or oceanic changes remains speculative; however, melt-induced weakening of the floating ice tongue in recent years is strongly suggested.

Keywords:

• Greenland
• outlet glaciers
• iceberg calving
• satellite remote sensing