Simulating the Laurentide Ice Sheet of the Last Glacial Maximum

• Published in: The Cryosphere
• Main Authors: Moreno-Parada, Daniel, Alvarez-Solas, Jorge, Blasco, Javier, Montoya, Marisa, Robinson, Alexander
• Other Authors: Ministerio de Ciencia e Innovación (España)
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union 2023
• Subjects: Ice Sheet; The Cryosphere
• Online Access: http://hdl.handle.net/10261/359530; https://doi.org/10.5194/tc-17-2139-2023; https://api.elsevier.com/content/abstract/scopus_id/85163656529

In the last decades, great effort has been made to reconstruct the Laurentide Ice Sheet (LIS) during the Last Glacial Maximum (LGM; ca. 21000 years before present, 21kyr ago). Uncertainties underlying its modelling have led to notable differences in fundamental features such as its maximum elevation, extent and total volume. As a result, the uncertainty in ice dynamics and thus in ice extent, volume and ice stream stability remains large. We herein use a higher-order three-dimensional ice sheet model to simulate the LIS under LGM boundary conditions for a number of basal friction formulations of varying complexity. Their consequences for the Laurentide ice streams, configuration, extent and volume are explicitly quantified. Total volume and ice extent generally reach a constant equilibrium value that falls close to prior LIS reconstructions. Simulations exhibit high sensitivity to the dependency of the basal shear stress on the sliding velocity. In particular, a regularised Coulomb friction formulation appears to be the best choice in terms of ice volume and ice stream realism. Pronounced differences are found when the basal friction stress is thermomechanically coupled: the base remains colder, and the LIS volume is lower than in the purely mechanical friction scenario counterpart. Thermomechanical coupling is fundamental for producing rapid ice streaming, yet it leads to a similar ice distribution overall. We thank Félix Garcia-Pereira for suggesting the two-phase regression method to determine the equilibration time. We are grateful to Julien Seguinot, Niall Gandy and the editor Chris R. Stokes for their comments, which have greatly improved our paper. Financial support This research has been supported by the Spanish Ministry of Science and Innovation (project IceAge, grant no. PID2019-110714RA-100) and the Ramón y Cajal programme of the Spanish Ministry of Science and Innovation and the Spanish Ministry of Universities (grant no. RYC-2016-20587). This research is TiPES contribution no. 183 and has been ...