Last glacial cycle glacier erosion potential in the Alps

Abstract. The glacial landscape of the Alps has fascinated generations of explorers, artists, mountaineers and scientists with its diversity, including erosional features of all scales from high-mountain cirques, to steep glacial valleys and large over-deepened basins. Using previous glacier modelling results, and empirical inferences of bedrock erosion under modern glaciers, we compute a distribution of potential glacier erosion in the Alps over the last glacial cycle from 120 000 years ago to the present. Despite large uncertainties pertaining to the climate history of the Alps and unconstrained glacier erosion processes, the resulting modelled patterns of glacier erosion include persistent features. The cumulative imprint of the last glacial cycle shows a very strong localization of glacier erosion with local maxima at the mouths of major Alpine valleys and some other upstream sections where glaciers are modelled to have flown with the highest velocity. The modelled erosion rates vary significantly through the glacial cycle, but show paradoxically little relation to the total glacier volume. Phases of glacier advance and maximum extension see a localization of rapid erosion rates at low elevation, while glacier erosion at higher elevation is modelled date from phases of less extensive glaciation. The modelled erosion rates peak during deglaciation phases, when frontal retreat results in steeper glacier surface slopes, implying that climatic conditions that result in rapid glacier erosion might be quite transient and specific. Our results depict the Alpine glacier erosion landscape as a time-transgressive patchwork, with different parts of the range corresponding to different glaciation stages and time periods.