Glacier basal motion is responsible for a large part of ice flux in temperate alpine glaciers and outlet glaciers of ice sheets. However, the hydromechanical processes by which basal water controls sliding at the glacier bed are poorly known in large part because observations are very scarce. Consequently, the impact of surface melting and meltwater input on the future of mountain glaciers and outlet glaciers of ice sheets remains unclear. Here, we use a comprehensive data set of in situ measurements performed over 2 years on the Argentière Glacier in the French Alps, complemented by state-of-the-art ice flow and hydrology modeling, to investigate changes in water storage at the ice-bedrock interface. We find strikingly large uplifts ranging between 0.20 and 0.90 m over the winter/spring seasons in the ablation zone. We show that this uplift is mostly related to enhanced bed separation as a result of increased basal water storage. We expect this study to be helpful to the glaciological community studying basal sliding and its modulation by sub-glacial hydrology with a view of improving predictions of the future behavior of mountain glaciers and outlet glaciers of ice sheets.

Read more: Vincent C., A. Gilbert, A. Walpersdorf, F. Gimbert, O. Gagliardini, B. Jourdain, J. P. Roldan Blasco, O. Laarman, L. Piard, D. Six, L. Moreau, D. Cusicanqui and E. Thibert, 2022. Evidence of seasonal uplift in the Argentière Glacier (Mont Blanc area, France). Journal of Geophysical Research: Earth Surface, 127, e2021JF006454. doi:10.1029/2021JF006454