We provide an overview of geodetic survey designs conducted on 43 rock glaciers (RG) in the European Alps, embed these in an overview of the pioneering phase of monitoring RG movement, and compare our approaches with other studies. Different in-situ geodetic approaches used for the annual survey of RG velocity (RGV) and RG frontal advance (RGA) are examined. Geodetic-based RGV monitoring in the Alps started in 1918 and RGA in 1921. RGV is an associated parameter of the Essential Climate Variable “Permafrost” since 2022. Nowadays, satellite-based positioning or classic measurements with a total station are used for in-situ geodetic surveys. The total number of surveyed boulders at the 43 RGs varies from 1 to 206. In most cases, only a part of these points is considered as “reference points” used to calculate the RGV value of RG units. The density of reference points for RGV calculation ranges from 27.5 to 1143 pts./km2. For RGV monitoring using annual geodetic surveys, we suggest: (a) selecting a RG where multi-decennial monitoring seems to be feasible, (b) distributing uniformly observation points over the entire RG unit of interest along either profiles or well-distributed boulders, (c) repeating measurements always at the same time of the year (September), (d) site-RGV-averaging using all data points, (e) site-RGV-averaging using only the survey markers considered to be the most suitable for long-term monitoring, (f) providing additional statistical information of these points and in particular of the central flowline, and (g) securing long-term storage of original data, metadata and results.

Understanding geomorphological processes and landscape evolution is fundamental for UNESCO Global Geoparks (UGGPs), particularly those located in high-altitude, climate-sensitive areas. Concurrently, UGGPs require effective tools for the conservation, promotion, and management of geodiversity and geoheritage. This paper presents the digital Geomorphological Database (GDB) for the Adamello Brenta UGGp in the European Alps, a GIS-based framework documenting geomorphological processes and landforms across the entire protected area (approx. 1,100 km²). We adopted a consolidated and standardised GDB structure based on the guidelines for the Official Geomorphological Map of Italy at a 1:50,000 scale. Although not specifically designed for mountain areas, this database has proven to be a robust and transferable tool, suitable for documenting the complex Alpine geomorphology of the Geopark. It includes over 20,000 landforms, providing a quantitative knowledge base of the area’s geomorphological diversity. As a dynamic tool, the GDB can be updated with new data and is suitable for future multi-temporal analyses. It provides key support for crucial Geopark tasks, including geodiversity assessment, geoheritage promotion, territorial planning, and educational or geotourism activities. Its utility was successfully tested in the production of high-quality geomorphological maps, the planning of educational activities, land-use planning, and raising geohazard awareness. The GDB of the Adamello Brenta UGGp represents a fundamental scientific and management asset, bridging research with the practical needs of geoheritage protection, education, and sustainable development.

We present the first preliminary adaptation and implementation of the HOTSED framework in a high-altitude watershed of the Eastern Italian Alps chosen as pilot area. HOTSED was applied to assess the spatio-temporal variability of sediment source hotspots driven by rainfall-induced surface runoff across different climatic conditions and rainfall intensities. We analyzed four seasonal scenarios and four daily scenarios, including an ordinary event and three extreme events with different return periods (10-year, 30-year, and 50-year). A pre-existing polygon-based geomorphological map was used to spatially define sediment sources across the study area. The geomorphic potential of each sediment source was estimated through a qualitative scoring of map attributes, supported by semi-quantitative, spatially distributed indices, including slope, permafrost distribution, and a proxy for frost-cracking incidence on the bedrock. Structural sediment connectivity was estimated using a geomorphometric index based on a Digital Terrain Model. For each scenario, a proxy for sediment transport potential was computed using a rainfall-calibrated index, applying a 0 °C ground surface temperature threshold to exclude snow-covered areas. All components were then integrated through a raster-based equation, yielding the HOTSED model. Results show that hotspots become more widespread and geomorphologically active during warmer and wetter seasons, particularly in summer and autumn, due to a combination of higher cumulative rainfall, intensified thermo-mechanical weathering, and increased topographic-altitudinal control on water flows. The model successfully identified hotspot toposequences with a high potential to trigger hazardous cascade processes. The analysis shows that even moderate rainfall extremes (e.g., 10-year return period events) can significantly amplify hazard patterns. This highlights the importance of identifying and monitoring geomorphic responses and, hence, managing appropriately cascading systems in Alpine watersheds under changing climatic conditions.

Paleoclimatic glacial archives in low-latitude mountain regions are increasingly affected by melt, which leads to heavy percolation and can remove snow and firn accumulated across months, seasons, or even years. Proxy system models, used for improved interpretation of glacial proxies and paleoclimatic reconstructions, generally do not account for melt because they are optimized for sites where snow layer removal by melting is negligible. In this paper, we present a mass balance model applied to the Mt Ortles drilling site, at 3859 ma.s.l. in the Eastern Italian Alps, with the aim of building a pseudo-proxy of atmospheric conditions during the formation of snow layers that survived to ablation. This pseudo-proxy is useful for improved dating and environmental interpretation of firn layers (< 15 m depth), affected by significant melt in the period 1996-2011, which includes the extremely warm summer of 2003. Here we show that the model significantly improves the interpretation of the firn stratigraphy. This is fundamental for detecting melted layers and for refining the dating of the core based on traditional annual layer counting of stable isotope and pollen seasonal oscillations.

The present climate change is affecting geomorphic processes and landforms related to mountain permafrost in alpine areas. Impressive expressions of permafrost degradation include significant ground surface warming of rock glaciers, a general acceleration of rock-glacier surface-flow velocity, and rapid gravitational mass movements in steep terrains. In this context, the interest in mountain permafrost conditions in the Eastern Italian Alps is growing, in view of the possible consequences in terms of natural hazard assessment and mitigation, and of management of water resources. Therefore, there is a great need to assess the current and future changes of geomorphological processes and landform evolution related to degrading permafrost in this region.Here, we present the study approach and preliminary results of the ongoing project RETURN, which is an Extended Partnership funded by the European Union Next-GenerationEU (National Recovery and Resilience Plan – NRRP, Mission 4, Component 2, Investment 1.3 – D.D. 1243 2/8/2022, PE0000005). Our research group is working on the current and projected impacts of climate change on the alpine cryosphere of the Eastern Italian Alps. The activities of this project, which is focussing on the area of the Province of Trento, are aimed at: i) understanding the current local and regional permafrost state and distribution, ii) modelling the distribution and state of permafrost in future warming scenarios, and iii) determining whether the ongoing permafrost degradation is causing an increase of slope instability in terms of frequency and magnitude. These aims are accomplished by using a multidisciplinary approach that comprises a) photogrammetric analyses aimed at reconstructing interannual variations and possible acceleration of rock glacier kinematics, b) geophysics aimed at estimating the volume of permafrost in active and pseudo-relict rock glaciers, c) ground-surface temperature monitoring aimed at modelling the conditions of permafrost at local and regional scale, and d) geomorphological analyses of areas affected by landslides induced by permafrost degradation.The results of the RETURN project are expected to contribute to a better understanding of ongoing processes and similar issues in other mountain areas affected by warming and degrading permafrost.

In alpine areas, spring-water temperature is affected by the presence of permafrost and by changes in the periglacial domain caused by the current atmospheric warming. Our interest in spring-water temperature is related to the possibility of investigating the spatial distribution of alpine permafrost and its changes. In particular, spring-water temperature might be helpful as indicator of permafrost occurrence in areas where it is discontinuous or sporadic, and in general where its distribution is poorly known. The spring-water temperature in late summer is a useful evidence of permafrost, and various authors employed such method as auxiliary permafrost evidence, or as a stand-alone method that can be used for mapping permafrost distribution at the catchment scale. However, little is known on the spatial and temporal variability of water temperature at springs with different permafrost contribution and characteristics. Here we present an analysis of the spatial and temporal variability of spring-water temperature in a 795 km2 catchment located in the Eastern Italian Alps, aimed at investigating the spatial distribution of permafrost and its effect on spring-water temperature. From 2018 to 2021, we measured the late-summer spring-water temperature at 220 springs, 133 of which are located downslope of rock glaciers, 81 downslope of other deposits, and 8 in bedrock. In addition, we installed dataloggers for continuous temperature measurements at 31 springs. Results show that the cold springs are mainly associated with intact rock glaciers but also with rock glaciers classified as relict, especially if they have blocky and sparsely vegetated surface. Accordingly, the latter should be reclassified as pseudo-relict, i.e. they appear to be visually relict but host patchy permafrost, as confirmed by geophysics carried out at selected case studies. These results have important implications for the study and modelling of the hydrological, hydrochemical and ecological response of periglacial environments under ongoing climate change.

Cryospheric long-term timeseries get increasingly important. To document climate-related effects on long-term viscous creep of ice-rich mountain permafrost, we investigated timeseries (1995-2022) of geodetically-derived Rock Glacier Velocity (RGV), i.e. spatially averaged interannual velocity timeseries related to a rock glacier (RG) unit or part of it. We considered 50 RGV from 43 RGs spatially covering the entire European Alps. Eight of these RGs are destabilized. Results show that RGV are distinctly variable ranging from 0.04 to 6.23 m a-1. Acceleration and deceleration at many RGs are highly correlated with similar behaviour over 2.5 decades for 15 timeseries. In addition to a general long-term, warming-induced trend of increasing velocities, three main phases of distinct acceleration (2000-2004, 2008-2015, 2018-2020), interrupted by deceleration or steady state conditions, were identified. The evolution is attributed to climate forcing and underlines the significance of RGV as a product of the Essential Climate Variable (ECV) permafrost. We show that RGV data are valuable as climate indicators, but such data should always be assessed critically considering changing local factors (geomorphic, thermal, hydrologic) and monitoring approaches. To extract a climate signal, larger RGV ensembles should be analysed. Criteria for selecting new RGV-sites are proposed.

Runoff originating from ground ice contained in rock glaciers represents a significant water supply for lowlands. Pseudo-relict rock glaciers contain patchy permafrost but appear to be relict, and therefore they can be misinterpreted when using standard classification approaches. The permafrost content, spatial distribution and frequency of this type of rock glacier are poorly known. Therefore, identifying pseudo-relict rock glaciers that might still contain permafrost, and potentially ice, is crucial for understanding their hydrological role in a climate change context.This work analyses rock-glacier spring-water temperature in a 795 km2 catchment in the eastern Italian Alps to understand how many rock glaciers classified as relict could have spring-water temperatures comparable to active or transitional rock glaciers as possible evidence of their pseudo-relict nature. Spring-water temperature, often auxiliary to other approaches for specific sites, was used for a preliminary estimate of the permafrost presence in 50 rock glaciers classified as relict. In addition, we present electrical resistivity tomography (ERT) results on two relict rock glaciers with opposing spring-water temperature and surface characteristics to constrain spring-water temperature results at the local scale.The results show that about 50 % of the rock glaciers classified as relict might be pseudo-relict, thus potentially containing permafrost. Both supposedly relict rock glaciers investigated by geophysics contain frozen sediments. The majority of the cold springs are mainly associated with rock glaciers with blocky and scarcely vegetated surfaces, but geophysics suggest that permafrost may also exist in rock glaciers below 2000 m a.s.l., entirely covered by vegetation and with a spring-water temperature of up to 3.7 degrees C. We estimate that pseudo-relict rock glaciers might contain a significant portion (20 %) of all the ice stored in the rock glaciers in the study area. These results highlight the relevance of pseudo-relict rock glaciers in periglacial environments. Even if not a conclusive method, spring-water temperature analyses can be used to preliminarily distinguish between relict and pseudo-relict rock glaciers in wide regions.

This is a correction for Kellerer-Pirklbauer et al (2024 Environ. Res. Lett. 19 034022).

The climatic response of mountain permafrost and glaciers located in high-elevation mountain areas has major implications for the stability of mountain slopes and related geomorphological hazards, water storage and supply, and preservation of palaeoclimatic archives. Despite a good knowledge of physical processes that govern the climatic response of mountain permafrost and glaciers, there is a lack of observational datasets from summit areas. This represents a crucial gap in knowledge and a serious limit for model-based projections of future behaviour of permafrost and glaciers. A new observational dataset is available for the summit area of Mt Ortles, which is the highest summit of South Tyrol, Italy. This paper presents a series of air, englacial, soil surface and rock wall temperatures collected between 2010 and 2016. Details are provided regarding instrument types and characteristics, field methods, and data quality control and assessment. The obtained data series are available through an open data repository (https://doi.org/10.5281/zenodo.8330289, Carturan et al., 2023). In the observed period, the mean annual air temperature at 3830 m a.s.l. was between −7.8 and −8.6 ∘C. The most shallow layers of snow and firn (down to a depth of about 10 m) froze during winter. However, melt water percolation restored isothermal conditions during the ablation season, and the entire firn layer was found at the melting pressure point. Glacier ice is cold, but only from about 30 m depth. Englacial temperature decreases with depth, reaching a minimum of almost −3 ∘C close to the bedrock, at 75 m depth. A small glacier located at 3470 m a.s.l., close to the summit of Mt Ortles, was also found in cold conditions down to a depth of 9.5 m. The mean annual ground surface temperature was negative for all but one monitored sites, indicating cold ground conditions and the existence of permafrost in nearly all debris-mantled slopes of the summit. Similarly, the mean annual rock wall temperature was negative at most monitored sites, except the lowest one at 3030 m a.s.l. This suggests that the rock faces of the summit are affected by permafrost at all exposures.

The kinematic acceleration of rock glaciers observed in recent decades shows that the behavior of these landforms is related to climate change. Velocity variations on yearly to seasonal time scales are frequently investigated, but velocity changes measured on shorter time scales (i.e., on hourly resolutions) are as yet poorly investigated. We used a ground based synthetic aperture radar to investigate, on an hourly time scale, the displacement of a rock glacier located in Val Senales (European Alps, northern Italy). We observed velocity fluctuations occurring at a very regular pace, characterized by phases of sharp acceleration (up to 0.9 mm/hr) lasting 4-11 hr followed by long phases of stagnation lasting 13-20 hr. This study describes an unprecedented observation of an hourly velocity rhythm of an active rock glacier and opens up new perspectives in the analysis and interpretation of rock glacier kinematics.

Differences in the sex-ratio and morphometric parameters in cold-adapted ground beetles were analysed to investigate environmental heterogeneity at small scale in a periglacial contest of the European Alps. Four hundred and thirty specimens of two cold-adapted ground beetles - Nebria germarii (Heer, 1837) and Nebria castanea (Bonelli 1810) - were analysed in order to test the presence of variation in sex-ratio, sexual dimorphism and morphometric parameters in relation to the occurrence of ice, and other environmental variables. Specifically, the populations found on an ice-related landform (active rock glacier) were compared with those on ice-free landforms (a fossil rock glacier and a scree slope). Both species experience sex-dependent morphometric plasticity. In addition, sex-ratio is female -bi-ased, supporting female pioneering tendency in all the studied landforms. Two morphometric parameters resulted indirectly affected by the presence/absence of ice in the terrain: the head width decreases, while elytra width increases passing from ice-free to ice-related landform. Both these morphometric differences may be related to the increase of intra/interspecific competition and to the lower trophic availability. This study highlights that even if these high altitude cold-adapted species are able to survive on ice-free landforms, they probably find more favourable conditions on ice-related landforms. Since the two species show different sensitivity to the ice-presence, it is not always possible to detect this preference through abundances variability (e.g for N. castanea), but it necessary to use more detailed morphometric analysis. Head width and elytra width are good candidates as response traits of interstitial ice occurrence in stony terrains.

Most of the world’s mountain glaciers have been retreating for more than a century in response to climate change. Glacier retreat is evident on all continents, and the rate of retreat has accelerated during recent decades. Accurate, spatially explicit information on the position of glacier margins over time is useful for analyzing patterns of glacier retreat and measuring reductions in glacier surface area. This information is also essential for evaluating how mountain ecosystems are evolving due to climate warming and the attendant glacier retreat. Here, we present a non-comprehensive spatially explicit dataset showing multiple positions of glacier fronts since the Little Ice Age (LIA) maxima, including many data from the pre-satellite era. The dataset is based on multiple historical archival records including topographical maps; repeated photographs, paintings, and aerial or satellite images with a supplement of geochronology; and own field data. We provide ESRI shapefiles showing 728 past positions of 94 glacier fronts from all continents, except Antarctica, covering the period between the Little Ice Age maxima and the present. On average, the time series span the past 190 years. From 2 to 46 past positions per glacier are depicted (on average: 7.8).

The cryosphere (i.e. glaciers and permafrost) and its related landforms offer a wide range of ecosystem services, thus they have strong relationships with human population. Even if these harsh environments have often been regarded as inhospitable, there is a growing amount of literature on glacial biodiversity, specifically concerning European mountains. Glaciers and permafrost-related landforms (e.g. rock glaciers) host a variety of cold-adapted taxa, from bacteria to vertebrates. They have been included in the Natura 2000 network, specifically in the habitat type: Permanent Glaciers (code 8340), but their biodiversity is still poorly known. Even if local extinctions and population reductions of cold-adapted species due to glacier and permafrost shrinking have been already documented, none of the species living in this habitat type are listed in the Habitat Directive Annexes. With this commentary, we call for urgent actions for an ecological characterization of this habitat type in order to plan monitoring and management of the biodiversity hosted by them. An increased knowledge of this no longer permanent habitat appears particularly urgent, because it is not replaceable and is likely to go extinct in the next decades.

Mountain glacier shrinkage represents a major effect of the current global warming and 80–100% of the Alpine glaciers are predicted to vanish within the next few decades. As the thawing rate of mountain permafrost ice is much lower than for glacier ice, a shift from glacial to periglacial dynamics is predicted for Alpine landscapes during the 21st century. Despite the growing literature on the impacts of deglaciation on Alpine hydrology and ecosystems, chemical and biological features of waters emerging from Alpine rock glaciers (i.e. permafrost landforms composed by a mixture of ice and debris) have been poorly investigated so far, and knowledge on microbial biodiversity of headwaters is still sparse. A set of glacier-, rock glacier- and groundwater/precipitation-fed streams was investigated in the Italian Central Alps in late summer 2016, aiming at exploring bacterial community composition and diversity in epilithic and surface sediment biofilm and at verifying the hypothesis that rock glacier-fed headwaters represent peculiar ecosystems from both a chemical and biological point of view. Rock glacier-fed waters showed high values of electrical conductivity and trace elements related to their bedrock lithology, and their highly diverse bacterial assemblages significantly differed from those detected in glacier-fed streams. Bacterial taxonomic composition appeared to be mainly related to water and substrate type, as well as to water chemistry, the latter including concentrations of nutrients and trace metals. The results of this study confirm the chemical and biological peculiarity of rock glacier-fed waters compared to glacial waters, and suggest a potential driving role of thawing permafrost in modulating future ecological traits of Alpine headwaters within the context of progressing deglaciation.

Rock glacier inventories have been created for many mountainous regions in Europe and outside in the past decades. These GIS-based catalogues are an important source of information to investigate periglacial landscapes, such as exploring associations between permafrost phenomena and environmental conditions. In this context, a crucial information stored in rock glacier inventories are the activity status and the related ice content of the mapped landforms (“active”, “inactive”, “intact” or “relict”, and “fossil”). The assignment of the activity status is mostly done by individual operators based on morphological evidences found in the field, on aerial images and on digital terrain models, in some cases by field measurements with different methods. Even though this expert-based approach has proven to be highly valuable, it is also known to be time consuming and somewhat subjective concerning especially the definition of the status of the rock glaciers. Recent technological advances in satellite remote sensing techniques - coupled to new algorithms for multiple variable analysis - offer new possibilities for improving rock glacier classification. This study presents a novel, two-step

Rock glaciers are widespread periglacial landforms in mountain regions like the European Alps. Depending on their ice content, they are characterized by slow downslope displacement due to permafrost creep. These landforms are usually mapped within inventories, but understand their activity is a very difficult task, which is frequently accomplished using geomorphological field evidences, direct measurements, or remote sensing approaches. In this work, a powerful method to analyze the rock glaciers' activity was developed exploiting the synthetic aperture radar (SAR) satellite data. In detail, the interferometric coherence estimated from Sentinel-1 data was used as key indicator of displacement, developing an unsupervised classification method to distinguish moving (i.e., characterized by detectable displacement) from no-moving (i.e., without detectable displacement) rock glaciers. The original application of interferometric coherence, estimated here using the rock glacier outlines as boundaries instead of regular kernel windows, allows describing the activity of rock glaciers at a regional-scale. The method was developed and tested over a large mountainous area located in the Eastern European Alps (South Tyrol and western part of Trentino, Italy) and takes into account all the factors that may limit the effectiveness of the coherence in describing the rock glaciers' activity. The activity status of more than 1600 rock glaciers was classified by our method, identifying more than 290 rock glaciers as moving. The method was validated using an independent set of rock glaciers whose activity is well-known, obtaining an accuracy of 88%. Our method is replicable over any large mountainous area where rock glaciers are already mapped and makes it possible to compensate for the drawbacks of time-consuming and subjective analysis based on geomorphological evidences or other SAR approaches.

An overall acceleration of rock glacier displacement rates in the Alps has been observed in recent decades, with several cases of destabilization leading to potential geomorphological hazards. This behaviour has been attributed to the rising permafrost temperature, induced by atmospheric warming and regulated by thermo-hydrological processes. Landforms derived from the interaction of glacier remnants and permafrost are widespread in mountain areas, but are less studied and monitored than talus rock glaciers. This work presents a comparative study of a talus rock glacier and a glacial-permafrost composite landform (GPCL) in the Eastern Italian Alps. The two landforms are only 10 km apart, but have rather different elevation ranges and main slope aspects. The kinematics and ground thermal conditions were monitored from 2001 to 2015 along with geomorphological surveys, analyses of historical maps and remote sensing data. The dynamic behaviour of the rock glacier was similar to the majority of monitored rock glaciers in the Alps, with an acceleration after 2008 and a velocity peak in 2015. In contrast, the GPCL had a nearly unchanged displacement rate during the observation period. Statistical analyses of kinematic vs. nivo-meteorological variables revealed a dynamic decoupling of the two landforms after 2008 that corresponds with increased winter snow accumulation. Although the kinematics of both landforms respond to ground surface temperature variations, the collected evidence suggests a different reaction of ground surface temperature to variations in the precipitation regime. This different reaction is likely due to local topo-climatic conditions that affect snow redistribution by wind. The different reactions of the two systems to the same climatic forcing is likely a legacy of their different origins. GPCL dynamics result from interaction of permafrost and residual glacial dynamics that are associated with possible peculiarities in the internal/basal meltwater circulation, whose future response is uncertain and requires improved understanding. (c) 2019 John Wiley & Sons, Ltd.