Articles | Volume 10, issue 2
The Cryosphere, 10, 639–664, 2016
The Cryosphere, 10, 639–664, 2016

Research article 16 Mar 2016

Research article | 16 Mar 2016

Numerical simulations of the Cordilleran ice sheet through the last glacial cycle

Julien Seguinot1,2,3, Irina Rogozhina3,4, Arjen P. Stroeven2, Martin Margold2, and Johan Kleman2 Julien Seguinot et al.
  • 1Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zürich, Zürich, Switzerland
  • 2Department of Physical Geography and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 3Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 4Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany

Abstract. After more than a century of geological research, the Cordilleran ice sheet of North America remains among the least understood in terms of its former extent, volume, and dynamics. Because of the mountainous topography on which the ice sheet formed, geological studies have often had only local or regional relevance and shown such a complexity that ice-sheet-wide spatial reconstructions of advance and retreat patterns are lacking. Here we use a numerical ice sheet model calibrated against field-based evidence to attempt a quantitative reconstruction of the Cordilleran ice sheet history through the last glacial cycle. A series of simulations is driven by time-dependent temperature offsets from six proxy records located around the globe. Although this approach reveals large variations in model response to evolving climate forcing, all simulations produce two major glaciations during marine oxygen isotope stages 4 (62.2–56.9 ka) and 2 (23.2–16.9 ka). The timing of glaciation is better reproduced using temperature reconstructions from Greenland and Antarctic ice cores than from regional oceanic sediment cores. During most of the last glacial cycle, the modelled ice cover is discontinuous and restricted to high mountain areas. However, widespread precipitation over the Skeena Mountains favours the persistence of a central ice dome throughout the glacial cycle. It acts as a nucleation centre before the Last Glacial Maximum and hosts the last remains of Cordilleran ice until the middle Holocene (6.7 ka).

Short summary
We use a numerical model based on approximated ice flow physics and calibrated against field-based evidence to present numerical simulations of multiple advance and retreat phases of the former Cordilleran ice sheet in North America during the last glacial cycle (120 000 to 0 years before present).