Marine ice-cliff instability modeling shows mixed-mode ice-cliff failure and yields calving rate parameterization

Area of Science:

• Glaciology
• Climate Science
• Earth System Science

Background:

• Marine ice-cliff instability (MICI) poses a significant threat to Antarctic ice loss.
• Over-deepened basins, like those in West Antarctica, are particularly vulnerable to MICI.
• Current models predict MICI could contribute over 1 meter to global sea level rise by 2100 under current emission rates.

Purpose of the Study:

• To enhance the understanding of structural failure modes in marine ice cliffs.
• To develop a conservative parameterization for ice-cliff failure retreat rates in ice-sheet models.

Main Methods:

• Utilized a suite of high-fidelity glacier models.
• Analyzed the roles of viscous deformation, shear-band formation, and brittle-tensile failure.
• Investigated the non-linear relationship between cliff height and calving rates.

Main Results:

• Identified viscous deformation, shear-band formation, and brittle-tensile failure as key modes of ice cliff structural failure.
• Quantified the non-linear increase in calving rates with increasing ice cliff height.
• Demonstrated that viscous flow and iceberg mélange back-force can inhibit runaway ice-cliff retreat.

Conclusions:

• MICI is a critical process for Antarctic ice loss and global sea level rise.
• The derived parameterization provides a more robust representation of ice-cliff failure for ice-sheet models.
• Further research into inhibiting factors like viscous flow and mélange is crucial for accurate sea-level rise projections.