From ice-shelf tributary to tidewater glacier: continued rapidrecession, acceleration and thinning of Rohss Glacier following the1995 collapse of the Prince Gustav Ice Shelf, Antarctic Peninsula

摘要

We use optical (ASTER and Landsat) and radar (ERS-1 and ERS-2) satellite imagery todocument changes in the Prince Gustav Ice Shelf, Antarctic Peninsula, and its tributary glaciers beforeand after its January 1995 collapse. The satellite image record captures the transition from an ice-shelfglacier system to a tidewater glacial system and the subsequent rapid retreat and inferred 'fatal' negativemass balances that occur as lower glacier elevations lead to higher ablation and tidewater-style calvingcollapse. Pre-1995 images show that the central ice shelf was fed primarily by Sjogren Glacier flowingfrom the Antarctic Peninsula and by Rohss Glacier flowing from James Ross Island. Numerous structuraldiscontinuities (rifts and crevasses) and melt ponds were present on the ice shelf before the collapse.After the ice shelf collapsed, Rohss Glacier retreated rapidly, becoming a tidewater glacier in 2002 andreceding a total of —15 km between January 2001 and March 2009, losing >70% of its area. Topographicprofiles of Rohss Glacier from ASTER-derived digital elevation models show a thinning of up to —150 m,and surface speeds increased up to ninefold (0.1-0.9 m *V) over the same period. The rates of speedincrease and elevation loss, however, are not monotonic; both rates slowed between late 2002 and 2005,accelerated in 2006 and slowed again in 2008-09. We conclude that tributary glaciers react to ice-shelfremoval by rapid (if discontinuous) recession, and that the response of tidewater glaciers on the AntarcticPeninsula to ice-shelf removal occurs over timescales ranging from sub-annual to decadal.