Glacier geometry and flow speed determine how Arctic marine-terminating glaciers respond to lubricated beds

Basal conditions directly control the glacier sliding rate and the dynamic discharge of ice. Recent glacier destabilization events indicate that some marine-terminating glaciers quickly respond to lubricated beds with increased flow speed, but the underlying physics, especially how this vulnerability relates to glacier geometry and flow characteristics, remains unclear. This paper presents a 1D physical framework for glacier dynamic vulnerability assuming sudden basal lubrication as an initial perturbation. In this new model, two quantities determine the scale and the areal extent of the subsequent thinning and acceleration after the bed is lubricated: Peclet number (Pe) and the product of glacier speed and thickness gradient (dubbed J(0) in this study). To validate the model, this paper calculates Pe and J(0) using multi-sourced data from 1996 to 1998 for outlet glaciers in the Greenland ice sheet and Austfonna ice cap, Svalbard, and compares the results with the glacier speed change during 1996/1998-2018. Glaciers with lower Pe and J(0) are more likely to accelerate during this 20-year span than those with higher Pe and J(0), which matches the model prediction. A combined factor of ice thickness, surface slope, and initial flow speed physically determines how much and how fast glaciers respond to lubricated beds in terms of speed, elevation, and terminus change.

Automated summary

This paper presents a new model to explain the response of glaciers to basal lubrication. By validating the model using data from 1996 to 1998, it was found that glaciers with lower Peclet number and product of glacier speed and thickness gradient are more likely to accelerate over a 20-year period.