DOI: 10.1594/pangaea.971350
title: Length changes of Austrian glaciers in 2022/2023

description: Glacier length change data of 93 Austrian glaciers were collected for the period summer/autumn 2022 to summer/autumn 2023 (variable period for each glacier depending on specific measurement dates). The measurements in 2023 have been carried out by 19 different teams led by one or two investigators each (altogether 24 team leaders). The 93 monitored glaciers are well distributed over the glaciated mountain ranges of the Austrian Alps and consider both small and some of the largest glaciers (up to ca.15 km²; e.g., Pasterze Glacier) in Austria. Therefore, this sample is representative for all present-day glaciers in Austria. The monitored glaciers extend from latitude 46°33'N to 47°30'N and longitude 10°04'E to 13°39' E. The data published here comprise the glacier-length-change results for the glaciological year 2022-2023 and are based on a paper published in the official magazine of the Austrian Alpine Club named Bergauf (https://www.alpenverein.at/bk/bergauf/bergauf2024/Bergauf_2_2024). The collected data are also stored in the database of the World Glacier Monitoring Service (WGMS) in Zurich, Switzerland (https://wgms.ch/). Glacier changes at the 93 glaciers was measured in different ways. First, at 72 glaciers the position of the terminus was quantified for 2023 by measuring the distance between distinct marked points in the proglacial area and the ice margin in clearly defined directions (azimuths) for both years. The difference of the measured distances in 2022 and 2023 yields the glacier length change for one specific point. By calculating the arithmetic mean of several of such marked points at a given glacier, the glacier change value was obtained for glaciers with more than one marked point. Second, at nine Austrian glaciers the position of the glacier terminus was quantified for 2023 using Global Navigation Satellite System (GNSS) techniques, unmanned aerial systems (UAS/drones), or other geodetic instruments which allow the measurement of the glacier terminus in both years. Based on these two GNSS/UAS/geodetic data sets, the glacier length change value was quantified for 2022/2023. Third, for eleven glaciers the change of the glacier position was qualitatively determined by photograph comparison or two-year glacier length-change data. For one glacier (Schneeloch Glacier), a two-year value for the glacier retreat was given, as there is no data for 2022. For a further glacier (Hintereis Ferner) the determination of the glacier terminus was uncertain. These were not considered when calculating the overall mean value. Results of our analysis show that all but one of the observed glaciers (n=92) retreated. Monitoring activities were stopped at one glacier in 2023 (Weisssee Ferner) due to the lack of a measurable glacier size. The mean value of the glacier retreat rate of the 79 glaciers with metric data in 2022 and 2023 was 23.9 m/a (compared to 28.7 m/a in the previous year). This is the third highest value in the entire history of the glacier measurement service of the Austrian Alpine Club initiated 133 years ago. The highest retreat value measured was 203.5 m/a at Pasterze Glacier, Glocknergruppe (Glockner Mountains). Regarding the wider context of these results: glacier length changes of Austrian Glaciers are measured annually within the framework of a monitoring program of the Austrian Alpine Club. This program is one of the longest glacier monitoring programs and runs since 1891. Regular measurements of length variations in Austria at single glaciers have been started even earlier. Since 1879, glaciological surveys have been carried out almost annually at for instance Pasterze Glacier, Glocknergruppe (Glockner Mountains) representing one of the longest time series of continuous glacier monitoring worldwide. For more details regarding the glacier monitoring program of the Austrian Alpine Club visit https://www.alpenverein.at/portal/museum-archiv/gletschermessdienst/index.php (only in German).