Reconstructed glacier area and volume changes in the European Alps since the Little Ice Age

Abstract. Glaciers in the European Alps have experienced drastic area and volume loss since the end of the Little Ice Age (LIA) around the year 1850. How large these losses were is only poorly known as, published estimates of area loss are mostly based on simple up-scaling and alpine-wide reconstructions of LIA glacier surfaces are lacking. For this study, we compiled all digitally available LIA glacier extents for the Alps and added missing outlines for glaciers >0.1 km² by manual digitising. This was based on geomorphologic interpretation of moraines and trimlines on very high-resolution images in combination with historic topographic maps and modern glacier outlines. Glacier area changes are determined for all glaciers with LIA extents at a regional scale. Glacier surface reconstruction with a Geographic Information System (GIS) was applied to calculate (a) glacier volume changes for the entire region from the LIA until today and (b) total LIA glacier volume in combination with a reconstructed glacier bed. The glacier area shrunk by 2405 km² (-57 %) from 4211 km² at the LIA maximum to 1806 km² in 2015 and volume was reduced from about 281 km³ around 1850 to 100 km³ (‑65 %) in 2015, roughly in line with previous estimates. In the mean, glacier surfaces lowered by -43.3 m until 2015 (-0.25 m a^-1), which is three-times less than observed over the 2000 to 2015 period (-0.82 m a^-1). Strongest volume losses occurred around 1600 m and at least 1832 glaciers melted away completely. Many glaciers have now only remnants of their former coverage left, which led to deglaciation of entire catchments. The new datasets should support a wide range of studies related to the effects of climate change in the Alps.