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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 10 | Copyright
The Cryosphere, 12, 3265-3285, 2018
https://doi.org/10.5194/tc-12-3265-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 10 Oct 2018

Research article | 10 Oct 2018

Modelling last glacial cycle ice dynamics in the Alps

Julien Seguinot1,2, Susan Ivy-Ochs3, Guillaume Jouvet1, Matthias Huss1, Martin Funk1, and Frank Preusser4 Julien Seguinot et al.
  • 1Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zürich, Zurich, Switzerland
  • 2Arctic Research Center, Hokkaido University, Sapporo, Japan
  • 3Laboratory of Ion Beam Physics, ETH Zürich, Zurich, Switzerland
  • 4Institute of Earth and Environmental Sciences, University of Freiburg, Freiburg, Germany

Abstract. The European Alps, the cradle of pioneering glacial studies, are one of the regions where geological markers of past glaciations are most abundant and well-studied. Such conditions make the region ideal for testing numerical glacier models based on simplified ice flow physics against field-based reconstructions and vice versa.

Here, we use the Parallel Ice Sheet Model (PISM) to model the entire last glacial cycle (120–0ka) in the Alps, using horizontal resolutions of 2 and 1km. Climate forcing is derived using two sources: present-day climate data from WorldClim and the ERA-Interim reanalysis; time-dependent temperature offsets from multiple palaeo-climate proxies. Among the latter, only the European Project for Ice Coring in Antarctica (EPICA) ice core record yields glaciation during marine oxygen isotope stages 4 (69–62ka) and 2 (34–18ka). This is spatially and temporally consistent with the geological reconstructions, while the other records used result in excessive early glacial cycle ice cover and a late Last Glacial Maximum. Despite the low variability of this Antarctic-based climate forcing, our simulation depicts a highly dynamic ice sheet, showing that Alpine glaciers may have advanced many times over the foreland during the last glacial cycle. Ice flow patterns during peak glaciation are largely governed by subglacial topography but include occasional transfluences through the mountain passes. Modelled maximum ice surface is on average 861m higher than observed trimline elevations in the upper Rhône Valley, yet our simulation predicts little erosion at high elevation due to cold-based ice. Finally, despite the uniform climate forcing, differences in glacier catchment hypsometry produce a time-transgressive Last Glacial Maximum advance, with some glaciers reaching their modelled maximum extent as early as 27ka and others as late as 21ka.

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About 25 000 years ago, Alpine glaciers filled most of the valleys and even extended onto the plains. In this study, with help from traces left by glaciers on the landscape, we use a computer model that contains knowledge of glacier physics based on modern observations of Greenland and Antarctica and laboratory experiments on ice, and one of the fastest computers in the world, to attempt a reconstruction of the evolution of Alpine glaciers through time from 120 000 years ago to today.
About 25 000 years ago, Alpine glaciers filled most of the valleys and even extended onto the...
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