Beschreibung: Glaciers in the Andes are among the fastest shrinking and largest contributors to sea level rise in the world. They also represent crucial water resources in many tropical and semi-arid portions of this extensive mountain range. Yet, the magnitude of the recent ice loss over the entire Andes cordillera is still debated. Here we present Andean glacier mass changes (from 10°N to 56°S) between 2000 and 2018 using time series of digital elevation models derived from ASTER stereo images. The total mass change is -22.9 ± 5.9 Gt yr-1 (-0.72 ± 0.22 m w.e. yr-1), with the most negative mass balances in the Patagonic Andes (-0.78 ± 0.25 m w.e. yr-1) and the Tropical Andes (-0.42 ± 0.24 m w.e. yr-1), and relatively moderate losses (-0.28 ± 0.18 m w.e. yr-1) in the Dry Andes. Sub-period analysis (2000-2009 vs. 2009-2018) reveals steady mass loss in the Tropics and south of 45°S. Conversely, a shift from slightly positive to strongly negative mass balance is measured between 26° and 45°S. In this latter region, the rapid glacier loss in recent years coincides with extremely dry conditions since 2010 and partially helped to mitigate the negative hydrological impacts of this severe drought. These results provide a comprehensive, high resolution and multi-decadal dataset of recent Andes-wide glacier mass changes that constitutes a relevant basis for calibration and validation of hydrological and glaciological models intended to project future glacier changes and their hydrological impacts.

Beschreibung: The on-going glacier shrinkage in the Alps requires frequent updates of glacier outlines to provide an accurate database for monitoring or modeling purposes (e.g. determination of run-off, mass balance, or future glacier extent) and other applications. With the launch of the first Sentinel-2 (S2) satellite in 2015, it became possible to create a consistent, Alpine-wide glacier inventory with an unprecedented spatial resolution of 10 m. Fortunately, already the first S2 images acquired in August 2015 provided excellent mapping conditions for most of the glacierised regions in the Alps. We have used this opportunity to compile a new Alpine-wide glacier inventory in a collaborative team effort. In all countries, glacier outlines from the latest national inventories have been used as a guide to compile a consistent update. However, cloud cover over many glaciers in Italy required including also S2 scenes from 2016. Whereas the automated mapping of clean glacier ice was straightforward using the band ratio method, the numerous debris-covered glaciers required intense manual editing. The uncertainty in the outlines was determined with multiple digitising of 14 glaciers by all participants. Topographic information for all glaciers was derived from the ALOS AW3D30 DEM. Overall, we derived a total glacier area of 1806 ±60 km² when considering 4394 glaciers 〉0.01 km². This is 14% (-1.2%/a) less than the 2100 km² derived from Landsat scenes acquired in 2003 and indicating an unabated continuation of glacier shrinkage in the Alps since the mid-1980s. Due to the higher spatial resolution of S2 many small glaciers were additionally mapped in the new inventory or increased in size compared to 2003. An artificial reduction to the former extents would thus result in an even higher overall area loss. Still, the uncertainty assessment revealed locally considerable differences in interpretation of debris-covered glaciers, resulting in limitations for change assessment when using glacier extents digitised by different analysts.

Beschreibung: Due to the many studies highlights a marked acceleration of rock glaciers after 1990s in the European Alps, a long-term monitoring dataset on Laurichard rock glacier (Ecrins National Parc) was established to investigate rock glacier behavior. Many historical and more recent aerial surveys from ~1950 until 2019 were processed using Structure for Motion (SfM) techniques. Classical Difference of DEM's (DoD) and feature tracking process were applied to document surface elevation changes and surface velocity displacements respectively, at a decadal time scale for 8 sub-periods. Additionally, 40 years of DGPS measurements were used as reference to validate our results. The data help to get more detailed insights into long-term rock glacier behavior and the relationship with climate forcing.