Lithosphere and Ice Sheet dynamics of West Antarctica

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The West Antarctic Rift System (WARS) is one of the largest continental rifts on earth, and it hosts the West Antarctic Ice Sheet (WAIS), which is currently in a state of rapid retreat and mass loss. A complete WAIS collapse, as predicted by some researchers, would result in a global sea level rise of three to five m. Predictions for future WAIS behaviour, however, are associated with high uncertainties, because its past evolution, particularly in response to global climate change and long-term tectonic processes, are poorly understood. The upcoming Polarstern expedition PS 104, scheduled for early 2017, offers the rare opportunity for collecting and investigating samples from the seldom visited Amundsen Sea sector of West Antarctica. This area experiences the highest glacial losses of whole Antarctica. The expedition also offers, for the very first time, the possibility of obtaining drilled sedimentary deposits from the Amundsen Sea, which record past advances and retreats of the WAIS. For this project plan, we aim to address the following topics and questions; (i) tectonic prerequisites and potential influences on glaciation: when did West Antarctic topography required for continental glaciation evolved, and where and when did rift branches of the WARS form, which may serve as pathways for warm ocean water and which may be characterized by elevated heat flow? (ii) Long-term glacial evolution: when was the WAIS initiated and how did it respond to previous periods of global warming and cooling? (iii) Establishment of modern glacial configurations: Following the LGM, how and when were current configurations achieved? Was glacial retreat a continuous process, or rather episodic, in concert with global Holocene climate and sea level variations? We will tackle these questions by applying a combination of thermochronological dating methods, isotope analysis, petrographic analysis, and surface exposure dating to bedrock, clastic deposits retrieved from the drill cores, and glacial erratics. The results of this project will contribute to an improved understanding of past WAIS behaviour and its controlling factors, which in turn will provide benchmarks for predicting the future WAIS behaviour and its impact on human society. The project plan refers to two of the superimposed topics of SPP 1158, namely to Development of the continent and to Dynamics of climate systems components.