Quantifying changes and trends in glacier area and volume in the Austrian Ötztal Alps (1969–1997–2006)

Abstract

Abstract. In this study we apply a simple and reliable method to derive recent changes in glacier area and volume by taking advantage of high resolution LIDAR (light detection and ranging) DEMs (digital elevation models) from the year 2006. Together with two existing glacier inventories (1969 and 1997) the new dataset enables to quantify area and volume changes over the past 37 years at three dates. This has been done for 81 glaciers (116 km2) in the Ötztal Alps which accounts for almost one third of Austria's glacier extent. Glacier area and volume have reduced drastically with significant differences within the individual size classes. Between 1997 and 2006 an overall area loss of 10.5 km2 or 8.2% occurred. Volume has reduced by 1.0 km3 which accounts for a mean thickness change of −8.2 m. The availability of three comparable inventories allows a comprehensive analysis of glacier changes over all size classes but lacks a high temporal resolution. We therefore used glacier length as well as mass balance measurements from all available glaciers within the study area to analyse the potential temporal course of glacier changes in terms of area and volume which allows a rough estimation of mean annual area and volume changes and thus acceleration trends. Comparing the net retreating period between 1969 and 1997 with the period 1997 to 2006, the analysis reveals that mean annual absolute area losses have remained constant. Relative area losses have accelerated slightly whereas volume as well as mean thickness losses have accelerated significantly.