Preprints
https://doi.org/10.5194/esurf-2021-26
https://doi.org/10.5194/esurf-2021-26

  31 Mar 2021

31 Mar 2021

Review status: this preprint is currently under review for the journal ESurf.

Climatic controls on mountain glacier basal thermal regimes dictate spatial patterns of glacial erosion

Jingtao Lai and Alison M. Anders Jingtao Lai and Alison M. Anders
  • Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA

Abstract. Climate has been viewed as a primary control on the rates and patterns of glacial erosion, yet our understanding of the mechanisms by which climate influences glacial erosion is limited. We hypothesize that climate controls the rates and patterns of glacial erosion by altering the basal thermal regime of glaciers. The basal thermal regime is a first-order control on the spatial patterns of glacial erosion. Polythermal glaciers contain both cold-based portions that protect bedrock from erosion and warm-based portions that actively erode bedrock. In this study, we model the impact of various climatic conditions on glacier basal thermal regimes and patterns of glacial erosion in mountainous regions. We couple a sliding-dependent glacial erosion model with the Parallel Ice Sheet Model (PISM) to simulate the evolution of the glacier basal thermal regime and glacial erosion in a synthetic landscape. We find that both basal thermal regimes and glacial erosion patterns are sensitive to climatic conditions and glacial erosion patterns follow the patterns of the basal thermal regime. Cold temperature leads to limited glacial erosion at high elevations due to cold-based conditions. Increasing precipitation can overcome the impact of cold temperature on the basal thermal regime by accumulating thick ice and lowering the melting point of ice at the base of glaciers. High precipitation rates, therefore, tend to cause warm-based conditions at high elevations, resulting in intensive erosion near the peak of the mountain range. Previous studies often assess the impact of climate on the spatial patterns of glacial erosion by integrating climatic conditions into the equilibrium line altitudes (ELAs) of glaciers, and glacial erosion is suggested to be maximal around the ELA. However, our results show that different climatic conditions produce glaciers with similar ELAs but different patterns of basal thermal regime and glacial erosion, suggesting that there might not be any direct correlation between ELAs and glacial erosion patterns.

Jingtao Lai and Alison M. Anders

Status: open (until 02 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2021-26', Simon Cook, 14 Apr 2021 reply

Jingtao Lai and Alison M. Anders

Jingtao Lai and Alison M. Anders

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Short summary
Glaciers are strong erosive agent and they have created many unique landforms in mountain belts. Climate has been viewed as a primary control on glacial erosion, yet our understanding of the mechanism by which climate impacts glacial erosion remains limited. Using computer simulations, we find that climate controls glacial erosion by modulating the temperature of the basal ice. Our results suggest that a warm and/or wet climate can create warm basal ice and therefore, enhance erosion.