Featured Science Paper
Grounding-line retreat of the West Antarctic Ice Sheet from inner Pine Island Bay
Over the last few decades, melting of glaciers in West Antarctica has contributed significantly to global sea-level rise. Since 1992 Pine Island Glacier and Thwaites Glacier, two major outlet glaciers draining the West Antarctic Ice Sheet into Pine Island Bay in the Amundsen Sea, have experienced up to 25 kilometres of landward retreat of their grounding line (i.e. the position at which the glacier margin starts to float). As both glaciers rest on a bed far below sea level, their grounding line may undergo further rapid retreat over coming decades.
This paper provides the long-term context of the ‘snapshot’ of ice-sheet history recorded over the last 20 years, which is crucial for predicting future ice loss and resulting sea-level rise. A BAS-led research team from the United Kingdom, Germany and Norway has reconstructed the timing of grounding-line retreat since the end of the last ice age about 12,000 years ago. The scientists analysed marine sediment cores recovered from the seafloor offshore from Pine Island Glacier and Thwaites Glacier. Radiocarbon dates obtained from tiny fossilised marine animals in the seabed sediments demonstrate that the grounding line of the two glaciers has been located within 110 kilometres of its modern position for the last 10,000 years. Currently, there is no evidence that the glaciers ever re-advanced. The new data imply that fast glacier retreat as observed today is unlikely to have happened more than three or four times in the last 10,000 years and therefore seems to be exceptional during this period of time.
Claus-Dieter Hillenbrand, Gerhard Kuhn, James A. Smith, Karsten Gohl, Alastair G.C. Graham, Robert D. Larter, Johann P. Klages, Rachel Downey, Steven G. Moreton, Matthias Forwick, and David G. Vaughan
GEOLOGY, January 2013; v. 41; no. 1; p. 35-38