Snowpatches are sensitive indicators of environmental change in mountain environments because their occurrence reflects interactions among topography, snow redistribution, and climate. Despite their ecological and geomorphological significance, snowpatches have never been systematically documented in the Gaspé Peninsula (eastern Canada). We combined Sentinel-2 imagery, a multi-year snowpatch recurrence inventory (2014–2025), GIS-derived topographic variables, Random Forest modeling, and climate projections to identify the factors controlling snowpatch distribution and evaluate their vulnerability to future climate change. Recurrent snowpatches were concentrated in a limited number of topographically favorable environments characterized by high elevation, reduced solar radiation, concave landforms, and predominantly east- to southeast-facing slopes. The relative importance of environmental factors associated with snowpatch occurrence differed between Mt. Albert and the McGerrigle Mountains, reflecting contrasts in landscape structure and vegetation cover. Climate projections indicate a substantial decline in regional snow-covered area during the twenty-first century under all future climate scenarios, with the strongest reductions occurring under high-emission pathways. These results demonstrate the strong dependence of recurrent snowpatch occurrence on nested topoclimatic controls and suggest that these features may become increasingly vulnerable under continued climatic warming.
The stabilization and persistence of organic carbon (OC) in soils and sediments is thought to be governed in large part by association with mineral matrices, especially reactive iron (Fe) phases. However, the role of these organo-mineral interactions has not been fully evaluated in lake sediments that are typically more OC rich. Here, we conducted detailed analyses of three sediment cores collected along a lake-depth gradient from a small clearwater lake in the Swedish Arctic to explore variability in sediment geochemistry and the role of mineral protection in OC preservation. While mineralogy of the two shallower, littoral cores was similar, mostly consisting of (alumino)silicates, sediments in the deepest part also included Fe-oxides and had 6-7 times higher specific surface area, indicating a greater potential for organo-mineral interactions. Higher specific surface area was strongly associated with more thermally-labile OC (rho = -0.71, p = 0.01), but not with OC stocks (rho = 0.05, p = 0.89). Multiple independent proxies indicated that deep-basin OC was more aliphatic, less degraded, and likely of planktonic algal origin compared to shallower regions. We suggest that the spatial pattern in OC quality is not simply a function of different OC sources or hydrodynamic sorting, but it is also regulated by differential capacity for organo-mineral stabilization.
Climate-driven glacier retreat is reorganizing sediment cascades across Alpine catchments. However, what remains poorly quantified is how their structural connectivity-the spatial configuration of landforms and pathways along which sediment can be transferred-evolves over deglaciation timescales. We reconstruct structural connectivity evolution in three glaciated catchments of the European Alps (i.e. Grastal, Kaunertal, Martelltal) over similar to 150 years since the Little Ice Age, using graph-based analysis of sediment cascade networks in which landforms are nodes and sediment pathways directed edges. Graphs were derived from multitemporal geomorphological maps combining historical maps, terrestrial photographs, Structure-from-Motion multi-view stereo (SfM-MVS) photogrammetry, and Airborne Laser Scanning (ALS)-derived DEMs, extending reconstruction to the 1870s-1890s. Despite similar deglaciation forcing, the three catchments followed divergent trajectories, with sources, links, and barriers evolving along site-specific rather than common paths. Changes were non-linear and episodic: glacier recession produced threshold-like reorganizations at Kaunertal and Grastal near the turn of the millennium, once retreating glaciers crossed topologically significant boundaries. Barrier positioning, not abundance, controlled system-scale filtering: a single strategically located lake in Grastal intercepted more sediment pathways than 13 lakes in Martelltal. Event-based routing showed connectivity increased in Kaunertal but declined in the other two via different mechanisms, indicating that network restructuring can outweigh source expansion in setting potential sediment delivery.
Glacier ice flow not only transports eroded rock material, but can also mobilize remnants of previous touristic activities, linking physical environment with human exploitation of mountains. Here, we investigate the transport and deposition of bottles and cans on a small, rapidly shrinking glacier in the Southeastern Swiss Alps. Object positions were documented using the global positioning system (GPS), and for several items, age estimates from literature and manufacturers suggest production dates between about 1900 and 1980. Field observations were combined with glaciological data and the results from a higherorder iceflow model to reconstruct their likely origin, transport pathways, and deposition period. The results indicate that the objects originated from the summit area of Piz Murt & egrave;l and were transported downslope by ice flow or by sliding over the surface, leading to the deposition of several hundred objects along the former glacier margin. We therefore conclude that bottles and cans were discarded near the summit of Piz Murt & egrave;l between more than a century and 50 years ago, and were then transported to form a morainelike shape. These findings demonstrate that glacierscale reconstructions of surface and englacial debris transport are feasible and highlight the role of glaciers as longterm archives of human activity in alpine environments.
The permafrost carbon cycle in Arctic coastal plains is strongly affected by abrupt thaw processes such as lake and hillslope thermokarst, which are expected to intensify under continued climate warming. Organic matter (OM) degradation may increase if taliks beneath drained lake basins (DLBs) fail to refreeze and retrogressive thaw slump activity accelerates. Thus, we investigated a coastal transect on the Baldwin Peninsula in northwest Alaska spanning a Yedoma upland, a thermokarst lake, a semidrained lake, a DLB, and a nearshore marine unit in proximity of a thaw slump. Using a 70-year aerial imagery analysis (1952-2022) with biogeochemical investigations of sediment cores (0-1 m), we assessed landscape and OM dynamics. We identified two dominant OM mobilization and decomposition trajectories. First, talik conditions favor OM degradation beneath the lake and the semidrained lake basin, where the talik did not completely refreeze for approximately 60 years following partial drainage. Second, thaw slump driven erosion mobilizes prealtered OM from the inland and transfers it into the marine environment, where further degradation occurs during sediment transport and reworking. In contrast, the upland and refrozen DLB currently preserve and sequester OM; yet, high ground ice contents render these systems vulnerable to future abrupt thaw.
