Permafrost thaw and destabilization of Alpine rock walls in the hot summer of 2003

TLDR

Exceptional rockfall occurred throughout the Alps during the unusually hot summer of 2003, likely due to rapid thermal reactions of steep slopes and destabilization of ice‑filled discontinuities. The study argues that future hotter summers predicted by climate models will reduce the stability of many alpine rock walls. The authors use measurements from Alpine rock faces to run model simulations that show how permafrost distribution degrades during the extreme thaw of 2003. The results indicate that rockfall can be a direct and unexpectedly rapid consequence of climate change, evidenced by extreme permafrost thaw in 2003.

Abstract

Exceptional rockfall occurred throughout the Alps during the unusually hot summer of 2003. It is likely related to the fast thermal reaction of the subsurface of steep rock slopes and a corresponding destabilization of ice‐filled discontinuities. This suggests that rockfall may be a direct and unexpectedly fast impact of climate change. Based upon our measurements in Alpine rock faces, we present model simulations illustrating the distribution and degradation of permafrost where the summer of 2003 has resulted in extreme thaw. We argue that hotter summers predicted by climate models for the coming decades will result in reduced stability of many alpine rock walls.