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

• Main Author: Zheng, Whyjay
• Format: Text
• Language: English
• Published: 2021
• Subjects: Arctic; Svalbard; Greenland; Austfonna; glacier; Ice cap
• Online Access: https://doi.org/10.5194/tc-2021-345; https://tc.copernicus.org/preprints/tc-2021-345/

Basal conditions directly control the glacier sliding rate and the dynamic discharge of ice flow. 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 1-D 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: Péclet number ( P e ) and the product of glacier speed and thickness gradient (dubbed J 0 in this study). To validate the model, this paper calculates P e and J 0 using multi-sourced data from 1996–1998 for outlet glaciers in Greenland and Austfonna Ice Cap, Svalbard, and compares the results with the glacier speed change during 1996/1998–2018. Glaciers with lower P e and J 0 are more likely to accelerate during this 20-year span than those with higher P e and J 0 , which matches the model prediction. A combined factor of ice thickness, surface slope, and initial speed for ice flow physically determines how much and how fast glaciers respond to lubricated beds, as forms of speed, elevation, and terminus change.