Rock glaciers are creeping bodies of ice and rock that account for an important part of the mountain cryosphere. In this study, we investigated long‐term changes of the Laurichard rock glacier (French Alps), to understand how this rock glacier is responding to climate change. Using feature‐tracking and photogrammetric measurements between 1952 and 2019, we quantified changes in thickness, flow velocities and from which we derived the ice/rock flux of the rock glacier at a decadal time scale. This is the first time that emergence velocity and surface mass balance changes have been reconstructed for a rock glacier. Our results reveal a very small surface mass balance ranging from −0.1 m a −1 to +0.05 m a −1, reflecting the role of debris in damping the melt rate of the underlying ice. Surprisingly, we found a more negative surface mass balance in the upper part than in the lower part of the rock glacier during the 1952–1971 cold period, likely due to a reduction in rock and snow mass accumulation. Our study shows that thickness changes are mainly driven by changes in surface mass balance except during the most recent period in the lower part of the rock glacier, which was also influenced by a compressive flow related to a protrusion that prevented the rock glacier from advancing. We conclude that the period 1994–2019 witnessed a marked acceleration in rock glacier flow, in agreement with the observations of other rock glaciers in the European Alps. This strong increase in surface speed is likely a consequence of changes in the basal conditions.
We used historical and modern aerial images to document changes in thickness, flow velocities, and the ice/rock flux of the rock glacier
This is the first time that emergence velocities and the surface mass balances have been reconstructed for a rock glacier
Strong marked acceleration of the entire rock glacier after 1990s, likely a consequence of changes in the basal conditions
See how this article has been cited at scite.ai
scite shows how a scientific paper has been cited by providing the context of the citation, a classification describing whether it supports, mentions, or contrasts the cited claim, and a label indicating in which section the citation was made.