Tracing glacier changes in Austria from the Little Ice Age to the present using a lidar-based high-resolution glacier inventory in Austria

Glacier inventories provide the basis for further studies on mass balance and volume change, relevant for local hydrological issues as well as for global calculation of sea level rise. In this study, a new Austrian glacier inventory has been compiled, updating data from 1969 (GI 1) and 1998 (GI 2) based on high-resolution lidar digital elevation models (DEMs) and orthophotos dating from 2004 to 2012 (GI 3). To expand the time series of digital glacier inventories in the past, the glacier outlines of the Little Ice Age maximum state (LIA) have been digitalized based on the lidar DEM and orthophotos. The resulting glacier area for GI 3 of 415.11 ± 11.18 km2 is 44% of the LIA area. The annual relative area losses are 0.3% yr−1 for the ~119-year period GI LIA to GI 1 with one period with major glacier advances in the 1920s. From GI 1 to GI 2 (29 years, one advance period of variable length in the 1980s) glacier area decreased by 0.6% yr−1 and from GI 2 to GI 3 (10 years, no advance period) by 1.2% yr−1. Regional variability of the annual relative area loss is highest in the latest period, ranging from 0.3 to 6.19% yr−1. The mean glacier size decreased from 0.69 km2 (GI 1) to 0.46 km2 (GI 3), with 47% of the glaciers being smaller than 0.1 km2 in GI 3 (22%).