Twitcher Glacier Accelerated Retreat, South Georgia island

Twitcher Glacier is the next glacier south of Herz Glacier on the east coast of South Georgia. Until 1989 the glacier ended at the tip of a peninsula, the ensuing retreat has led to the opening of a new fjord. Twitcher Glacier was 10 km long and had a 2 km wide calving front in 2009. The terminus change of this tidewater glacier was completed by the British Antarctic Survey for the 1960-2007 period. The glacier retreated 1.5 km between 1960 and 2007, with have of the retreat occurring after 1992. (Gordon et al, 2008). The map below indicates the slow retreat from 1960-1988 and a more rapid retreat since. twitcher glacier getwitcher glacier mapIn 1989 this glacier terminated approximately at the end of a peninsula separating the two glaciers. Here we examine Landsat imagery from 1989, 2000, 2009 and 2013 to identify the rate retreat. The 1989 terminus position is indicated with a yellow arrow and the 2009 terminus position with a red arrow. The retreat is 1.2 km during this period. From 2009 to 2013 retreat accelerated with a further 1.2 km retreat to the purple arrow in the 2013 imagery, the retreat may be even greater but the resolution is poor for the January 1, 2013 image. Notice the lake just south of the glacier terminus in 1989, this lake is evident in the 2000 and 2013 imagery, but is snowcovered in 2013. A 2012 MODIS image has poorer resolution but no cloud cover and indicates the extent of the retreat from the Peninsula the glacier had reached in 1989. The last image is a closeup in Google Earth from 2010 note the significant crevassing which is indicative of rapid flow. The terminus is currently quickly retreating to the next peninsula where the terminus will separate into two parts. The southern tributary already is partly exposed to calving into the fjord. The rapid retreat here is similar to that of Neumayer Glacier or Ross Hindle Glacier.
twitcher 1989

twitcher 2000

twitcher 2009

twitcher 2013twitcher 2012twitcher glacier terminus 2010


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