Abstract
The Greenland ice sheet is one of the most significant contributors to the rising global sea level with a contribution of 0.5 mm per year (Rignot & Kanagaratnam 2006). Evidence is emerging that rising temperatures of subsurface ocean currents play a vital role in the recent acceleration of large fast flowing glaciers such as Jakobshavn Isbræ in West Greenland (Holland et al. 2008) and Helheimgletscher in South-East Greenland (Straneo et al. 2010). Important questions are whether these incursions of warmer water are part of a recurrent phenomenon and indeed exactly how they influence the glaciers. The Geocenter Denmark project SEDIMICE (Linking sediments with ice-sheet response and glacier retreat in Greenland) investigates past ice fluctuations in the Helheimgletscher region in South-East Greenland with regard to magnitude, possible causes and effects. One of the main tasks in this project is to analyse sedimentary deposits in the main fjord Sermilik (Fig. 1), which is influenced by the tidally affected Helheimgletscher that has a short floating tongue. By combining sediment studies with modern climate studies we aim to extrapolate meteorological data back in time.
Highlights
The Greenland ice sheet is one of the most significant contributors to the rising global sea level with a contribution of 0.5 mm per year (Rignot & Kanagaratnam 2006)
Frequent glacial and geologically controlled fissure valleys dissect the area in a criss-cross pattern
The climate of the region is low arctic and the weather conditions are influenced by lows moving north along the coast
Summary
A study from the Toqqulertivit Imiat valley (Fig. 1) shows that a glacier flowed through this valley and most likely coalesced with a glacier flowing south in Sermilik and out over the continental shelf during the Last Glacial Maximum (Roberts et al 2008). Exposure ages of 11.8–9.9 ka (kilo-annum, 103 years BP) from bedrock surfaces at high elevations (683–740 m a.s.l.) provide minimum ages for the last deglaciation (Roberts et al 2008) These ages from Toqqulertivit Imiat support the ‘maximum’ model of a large Last Glacial Maximum ice sheet extending to the shelf break in SouthEast Greenland (Stein et al 1996; Kuijpers et al 2003). This is in accordance with surface exposure ages from lower Toqqulertivit Imiat indicating that ice retreated to the mouth of Sermilik between 11.1 and 9.7 ka (Roberts et al 2008) These data are further supported by a minimum age of 11 cal. These data are further supported by a minimum age of 11 cal. ka for the formation of the local marine limit (at 69 m) and thereby local ice retreat near Tasiilaq (Long et al 2008)
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