Articles | Volume 11, issue 1
The Cryosphere, 11, 427–442, 2017
The Cryosphere, 11, 427–442, 2017

Research article 08 Feb 2017

Research article | 08 Feb 2017

Simultaneous disintegration of outlet glaciers in Porpoise Bay (Wilkes Land), East Antarctica, driven by sea ice break-up

Bertie W. J. Miles, Chris R. Stokes, and Stewart S. R. Jamieson Bertie W. J. Miles et al.
  • Department of Geography, Durham University, Science Site, South Road, Durham, DH1 3LE, UK

Abstract. The floating ice shelves and glacier tongues which fringe the Antarctic continent are important because they help buttress ice flow from the ice sheet interior. Dynamic feedbacks associated with glacier calving have the potential to reduce buttressing and subsequently increase ice flow into the ocean. However, there are few high temporal resolution studies on glacier calving, especially in East Antarctica. Here we use ENVISAT ASAR wide swath mode imagery to investigate monthly glacier terminus change across six marine-terminating outlet glaciers in Porpoise Bay (76° S, 128° E), Wilkes Land (East Antarctica), between November 2002 and March 2012. This reveals a large near-simultaneous calving event in January 2007, resulting in a total of  ∼  2900 km2 of ice being removed from glacier tongues. We also observe the start of a similar large near-simultaneous calving event in March 2016. Our observations suggest that both of these large calving events are driven by the break-up of the multi-year sea ice which usually occupies Porpoise Bay. However, these break-up events appear to have been driven by contrasting mechanisms. We link the 2007 sea ice break-up to atmospheric circulation anomalies in December 2005 weakening the multi-year sea ice through a combination of surface melt and a change in wind direction prior to its eventual break-up in January 2007. In contrast, the 2016 break-up event is linked to the terminus of Holmes (West) Glacier pushing the multi-year sea ice further into the open ocean, making the sea ice more vulnerable to break-up. In the context of predicted future warming and the sensitivity of sea ice to changes in climate, our results highlight the importance of interactions between landfast sea ice and glacier tongue stability in East Antarctica.

Short summary
We observe a large simultaneous calving event in Porpoise Bay, East Antarctica, where ~ 2900 km2 of ice was removed from floating glacier tongues between January and April 2007. This event was caused by the break-up of the multi-year sea ice usually occupies the bay, which we link to climatic forcing. We also observe a similar large calving event in March 2016 (~ 2200 km2), which we link to the long-term calving cycle of Holmes (West) Glacier.