Erosion-deposition governs sediment dynamics and amplifies cascading hazards of glacial lake outburst floods

Glacial lake outburst hazard assessment linked to moraine dam and permafrost stability in Sikkim Himalaya

Glacial lake outburst floods (GLOFs) represent one of the most severe climate-induced hazards in high-mountain regions. The Shisper Glacier in Hassanabad Village, Hunza, Pakistan, has experienced repeated surge events and rapid ice-dammed lake expansion, posing escalating risks to downstream communities and critical infrastructure. This study presents a multi-temporal, multi-index remote sensing and GIS-based assessment of Shisper Glacier dynamics and associated GLOF hazards for the period 2020-2024. Landsat-8 OLI imagery was used to compute the normalized difference snow index (NDSI), normalized difference water index (NDWI), modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), land surface temperature (LST), land use and land cover (LULC), and green-red-NIR-shortwave infrared (GRZI) composite indices. Elevation change analysis was performed using the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM), while NASA POWER data provided climatological context for temperature, precipitation, and humidity patterns. The ice-dammed lake area at the glacier's snout was delineated using MNDWI-based water body extraction from Landsat-8 OLI imagery, and lake volume was estimated using a depth-area empirical scaling relationship, consistent with established methodologies for ice-dammed lakes in the Karakoram. Results indicate that the debris-covered glacier expanded from 161 km2 in 2015 to 197 km2 in 2018, while the ice-dammed lake exceeded 0.1 km2 with an estimated volume between 1 × 106 m3 and 10 × 106 m3, representing a substantial and growing GLOF hazard. Rising land surface temperatures and changing precipitation patterns are identified as key drivers of accelerated glacial melt. Approximately 80% of Hassanabad Village's infrastructure, including the Karakoram Highway Bridge and a nearby hydropower facility, lies within the projected GLOF inundation zone. The novelty of this study lies in the first integrated application of seven spectral indices combined with DEM-based surge mapping and infrastructure exposure assessment for Shisper Glacier within a unified hazard framework. These findings underscore the urgent need for continuous satellite-based monitoring, early warning systems, and risk-informed land-use planning in the Hunza region.

Mapping glacial lakes with glacial-lake compact efficient neural network (GCE-Net): perspectives on balancing model size and performance

Microplastics (MPs) are increasingly recognized as widespread contaminants in aquatic environments, including remote freshwater systems, where their presence is linked to waste generation and transport pathways. This study examined the occurrence, spatial–temporal distribution, polymer composition, and ecological risks of MPs in surface sediments from Black Lake and Devil Lake, two high-altitude glacial lakes in Durmitor National Park, Montenegro. Sediment samples were collected across three seasons and analyzed using standardized methods, including density separation, visual identification, and polymer characterization. MPs abundance averaged 5.1 ± 1.4 items per 100 g of dry sediment in Black Lake and 3.8 ± 0.5 items per 100 g in Devil Lake. Fibers and fragments were dominant morphotypes, with particles sized 1–3 mm prevailing. Blue particles were most frequent. Five polymer types were identified, with polyethylene as the dominant polymer. Pollution load index values indicated moderate contamination, while polymer hazard and ecological risk indices suggested high to very high environmental risk. The presence of MPs in protected, high-altitude glacial lakes highlights their vulnerability to diffuse pollution sources, including tourism and long-range transport. The findings provide baseline data for alpine freshwater environments and underline the importance of integrating MPs pollution into waste management and environmental protection strategies.

ABSTRACT Rapid glacier retreat across the Western Himalayas has led to the widespread expansion and deepening of proglacial lakes, increasing concerns over moraine stability and Glacial Lake Outburst Flood (GLOF) hazards. In this context, the present study investigates the coupled evolution of the Samudra Tapu glacier and its proglacial lake using multi-temporal Sentinel-1 SAR datasets spanning 2018–2024. The analysis focuses on lake-depth expansion toward the glacier snout and deformation of the moraine rim derived from InSAR-based techniques, enabling an assessment of their temporal interaction. Results indicate a progressive increase in lake depth from approximately 30 m during 2018–2020 to localized maxima of 60–69 m by 2023–2024. This evolution reflects enhanced and spatially variable meltwater inflow, subaqueous over-deepening, and alternating shallow–deep zones observed between 2020 and 2023. Concurrent InSAR-derived deformation patterns ranging from −0.52 m to +0.05 m correspond closely with periods of rapid lake deepening, suggesting moraine weakening driven by increased hydrostatic pressure. Notably, although lake depths appeared more balanced in 2024, deformation signals remained pronounced, indicating delayed mechanical responses of moraine materials to cumulative stress. Overall, integrating InSAR-based deformation mapping with satellite-derived bathymetry provides a robust framework for identifying instability zones and improving hazard assessment.

Glacier retreat transforms landscapes in polar and mountainous regions. Yet, the topography of the emerging terrain remains poorly known. Here, we present a physically consistent, global map of the ice-covered topography beneath all glaciers on Earth distinct from the ice sheets, derived from the three-dimensional higher-order Instructed Glacier Model, and constrained by extensive observational datasets. The map allows us to identify > 50,000 possible future lakes in the presently ice-covered landscape, with a maximum total volume of 3,138 km3—enough to store 7 mm sea-level equivalent (SLE). Additionally, we estimate the total global glacier volume at 149.41 ± 29.28 × 103 km3 (308 ± 60 mm SLE). Large overdeepenings near glacier fronts in High Mountain Asia suggest an increased risk for glacier lake outburst floods under glacier retreat. The subglacial topography and ice thickness data offer new opportunities for diverse cryospheric and Earth system studies, including refined projections of glacier changes and landscape evolution of deglaciated terrain.

Glacier lake outburst floods (GLOFs) pose a significant threat to human life and livelihoods in unstable glacier regions. One of the most significant consequences of climate change, GLOFs threaten local livelihoods, damage vital infrastructure, and intensify socioeconomic vulnerabilities. In this study, the relationship between economic losses, mental health problems, and social cohesion is examined using Applied Structural Equation Modeling Smart PLS 4. The results from 480 respondents demonstrate the complex consequences of GLOFs on community resilience. Major economic losses critically contribute to financial instability. Mental health outcomes, including stress and post traumatic stress disorder (PTSD), are widespread and exacerbated by displacement and loss of livelihoods. Social cohesion, on the one hand, facilitates collective action to cope and recover from crises, but on the other hand, social cohesion can also be lost when communities are strained by scarcity. This study highlights the need for disaster risk management measures that ensure the integration of mental health response, livelihood diversification, and strengthening of community-based resilience programs. By understanding the socioeconomic and psychological dimensions underlying GLOFs, policymakers and institutions in disaster management may deliver holistic interventions. The findings also offer a global perspective, with implications for other high-altitude, glacier-dependent regions across the world confronting similar challenges.

Biotic indicators of climate change in high altitude Tsoltak glacial lake of Ladakh Range, NW Trans-Himalaya, India

The accelerating retreat of glaciers and expansion of glacial lakes in the Trans-Himalayan region of Ladakh are intensifying the risk of Glacial Lake Outburst Floods (GLOFs), posing significant threats to vulnerable downstream communities. However, high-altitude basins like Lato remain poorly assessed in terms of integrated glacier–lake dynamics and hazard potential. In this study, we present a detailed, multi-parameter assessment of the Lato glacier–lake system over a 40-year period (1980–2020), combining remote sensing, empirical modeling, and hydrodynamic simulations. Our results show an ∼11.5% reduction in glacier area, a mean terminus retreat of ∼171 m at the rate of 4.2 m yr -1 , and a decline in total ice volume from 0.48 km 3 to 0.41 km 3 (1980–2020). Glacier surface velocities, derived using Glacier Image Velocimetry (GIV), ranged from 0.97 to 15.73 m yr -1 , with mean values between 7.63 and 8.03 m yr -1 . Ice thickness was estimated using GlabTop2 and ensemble modeling approaches, yielding average thicknesses of 76 m and 58 m, respectively. Geodetic mass balance calculations indicate a persistent negative trend, with an average loss of −0.33 m w.e. yr -1 since the early 2000s. The proglacial Lato lake expanded by ∼66%, reaching 0.088 km 2 in 2020. Lake depth and volume were estimated using multiple empirical models, with the most robust estimate placing the lake volume at 1.47 × 10 6 m 3 . GLOF susceptibility analysis using the Analytical Hierarchy Process (AHP) assigned a high-risk index of 0.82 to the lake. Two-dimensional hydrodynamic simulations using HEC-RAS under full and partial breach scenarios forecast peak discharges of 3726 m 3 s -1 and 2309 m 3 s -1 , respectively, with a potential impact zone extending ∼23 km downstream. This study not only identifies Lato lake as a high-risk GLOF site but also offers region-specific recommendations including glacier and lake monitoring, early warning systems, and the integration of GLOF risk into regional planning and disaster preparedness frameworks.

Bodanella lauterborni W.M. Zimmermann and Heribaudiella fluviatilis (Areschoug) Svedelius are members of brown algae (Phaeophyceae) that exclusively inhabit freshwater habitats. Heribaudiella fluviatilis is the most frequently reported freshwater brown alga, widely distributed in the Northern Hemisphere. In contrast, B. lauterborni, one of the rarest algae globally, has been reported in only four glacial Alpine lakes and has not been observed in nature for nearly 50 years. Since 2019, the species has been considered locally extinct at its type locality, and its presence in the other three lakes is also questionable. Here, we report the occurrence of B. lauterborni in three springs on the Vlasina Plateau (Southeast Serbia), being the first finding of the species in Southeast Europe and the fifth discovery globally in environmental conditions not previously described for the species. We also provide detailed data on the morphology, ecology, and biogeography of B. lauterborni and H. fluviatilis. Additionally, we report the non-obligate association Hildenbrandio rivularis-Heribaudielletum fluviatilis discovered in two rivers. Our findings significantly expand the known ecological and geographical range of phaeophytes, highlighting Southeast Europe as a refugium for freshwater Phaeophyceae biodiversity.

Glacial lake outburst floods (jökulhlaups) are challenging to study because they often take place below hundreds of meters of ice, and the complex interplay between lifting of the glacier and melting of the flood path is not well understood. Here, we provide unique insights into the mechanics of jökulhlaups and how they affect three-dimensional glacier motion using satellite synthetic aperture radar (SAR) and field observations, acquired before, during and after two recent jökulhlaups (in 2021 and 2022) from the subglacial lake Grímsvötn in Iceland. The results indicate that the same event may alternate between channel flow and sheet flow and that ponding of water along the subglacial flood path can play a major role in jökulhlaup dynamics. This has important implications for physical jökulhlaup modeling and for better understanding the role of subglacial hydraulics on glacier dynamics, required for improved predictions of the future evolution of glaciers and ice sheets.

SWOT performance in monitoring water level of high-mountain lakes on the Tibetan Plateau

Successful animal migration hinges on navigation and decision-making in dynamic environments. Yet, how individuals navigate transient, fine-scale landscape barriers, such as seasonally ice-covered water bodies, remains poorly understood. Understanding these responses is critical for forecasting migration routes and connectivity under global change. In the Arctic, rising temperatures are causing earlier ice melt and later freeze-up, reshaping landscape permeability and potentially disrupting migration routes for overland migrants, such as barren-ground caribou (Rangifer tarandus), a keystone Arctic species, which relies on frozen lakes and rivers for efficient spring travel to calving grounds. While caribou generally prefer ice to open water, behavioral responses to changing ice conditions have not been quantitatively assessed. We analyzed 20 years (2001-2021) of GPS data for 406 adult caribou and daily MODIS land surface albedo to examine lake-crossing decisions at Contwoyto Lake, a long (> 100 km) glacial lake in northern Canada. We classified transit events as crossing or circumnavigation based on GPS trajectories relative to lake boundaries and linked behavioral decisions to spatially and temporally resolved ice conditions. Our models revealed distinct seasonal drivers. Spring crossing decisions were shaped by intermediate-scale ice conditions, with a behavioral threshold at a path-averaged annual albedo percentile rank of 0.56, corresponding to intermediate late-spring melt conditions when lake ice transitions from continuous cover toward fragmented surfaces. In fall, when the lake was ice-free, movement-related factors such as relative speeds along alternative routes better explained behavior. Our findings show how ice acts as a seasonal behavior filter, shaping functional connectivity through perceptual and energetic constraints. Although developed for caribou, this framework is transferable across species and systems. By linking high-resolution, spatiotemporal remote sensing to individual behavior, our framework identifies quantitative behavioral thresholds in response to dynamic, climate-sensitive landscape features, supporting predictive monitoring of climate-driven shifts in migratory behavior and emerging constraints on movement.

Daily imaging from China's HJ-2A/B satellites enables yearly mapping of regional glacial lakes

Identification of asynchronous overtopping hazard patterns of glacial lakes in the Yarlung Tsangpo Basin

During the current study, the causes, impacts, and mitigation efforts related to Glacial Lake Outburst Floods (GLOFs) in Bilhanz and Badswat, Ishkoman Valley, were thoroughly examined between July to September 2024. These events led to significant landscape alterations, transforming once fertile agricultural and forest lands into debris covered areas, as evidenced by satellite and digital camera imagery. A large lake formed in Badswat, destroying extensive agricultural and forest land, which forced the relocation of many residents. Most displaced individuals received housing support from the Aga Khan Agency for Habitat (AKAH), while the government provided limited assistance. The Saudi government also made notable contributions. Between 2018 and 2021, successive GLOF events damaged 186 hectares of agricultural land in both villages in addition to damages and losses to livestock and other life supporting systems. Climate change and deforestation were identified as the primary drivers of these disasters. A multivariate analysis revealed that gender, age, and education had significant impacts on awareness and perceptions of environmental degradation and climate change. Older respondents, particularly those aged 50-60, were the most influential in shaping future disaster preparedness and mitigation efforts. Although education had a smaller effect size, it still played a crucial role in raising environmental awareness. Mitigation strategies proposed include afforestation, carbon capture, renewable energy, and waste reduction. Many respondents emphasized the importance of community involvement and education in addressing environmental issues. However, opinions vary on the most effective methods for controlling soil pollution and improving overall environmental health.

Lakes of the White Sea coast have altered owing to postglacial land uplift, changing from marine lagoon to freshwater conditions. The Lake Krivoe (deep, transparent, and stratified) at the Cape Kartesh (northern Karelia) formed via isolation from the sea and is made up of two basins filled with organic-rich sediments. As for the trophic status, the pelagic zone of the lake has remained oligotrophic since the 1960s. Diatoms and phytopigments were studied in a sediment core from a deep part of the lake. A high concentration of valves of benthic and periphytonic diatom species was observed in the core, indicating a significant contribution of these producers to the lake productivity. The lake bottom sediments were classified as highly productive (hypertrophic) based on their phytopigment concentration. Thus, benthic producers can play a key role in the ecosystems of arctic lakes, and the idea is important to consider when monitoring.

Glacial Lake Outburst Floods (GLOFs) are an increasing hydro-meteorological hazard in the high-altitude areas of northern Pakistan, which is enhanced due to the increased glacial melt under human-induced climate change. This paper examines the spatial-temporal occurrence of GLOFs and assesses the socio-economic impact of GLOFs on down-stream communities in Gilgit-Baltistan (GB) and Chitral District, in the Hindu Kush-Karakoram ranges. The study is based on multi-temporal satellite imagery (Landsat and Sentinel series), historical inventory of the Pakistan Meteorological Department (PMD) and International Centre for Integrated Mountains Development (ICIMOD) highly-resolution digital elevation models, and field-based measurements in 12 high-risk valleys, showing a striking 38% increase in GLOF events over the 35-year period, with intense acceleration since Out of 3,044 glacial lakes identified over GB and neighboring Khyber Pakhtunkhwa, 33 are considered to be potentially dangerous, exposing over 7 million people to increased risk. Socio-economic effects were measured using 450 household surveys, semi-structured interviews with 85 key informants, and a geospatial combination of flood inundation maps and census, agricultural and infrastructure data. Notable disasters, such as the Gupis GLOF in Ghizer in August 2025 (destroying more than 300 houses, the Ghizer River, and displacing hundreds), demonstrate an average direct loss of USD 45 million per major outburst, mainly by destroying irrigated agricultural land (42%), road and bridge networks (31%), hydropower and irrigation systems (18% The indirect impacts (livelihood disruption, temporary migration, food insecurity, and increased poverty) lasted 4-8 years after the event, and they were disproportionately on agrarian households, women and indigenous populations with a low adaptive capacity. Vulnerability mapping identifies hotspots that are a combination of physical exposure and socio-economic marginalization. This analysis places GLOF risk as a deep-rooted socio-economic amplifier in GB and Chitral by moving beyond glaciological drivers to pre-empt human dimensions. Results highlight the necessity of combined, community-based adaptation plans, such as more effective early-warning systems, nature-based response, and transboundary risk-financing framework, to achieve resilience in current cryospheric change.

During the final retreat of the Laurentide Ice Sheet, large volumes of meltwater from the Hudson Bay region entered the North Atlantic leading to one of the strongest freshwater perturbations of the Holocene. The resulting 8.2 ka cold event is a key benchmark for understanding ice-sheet–ocean interactions, yet the timing, structure, and mechanisms of this freshwater release from Hudson Bay remain debated. New sediment records from Hudson Strait document a sequence of ice–ocean reorganisations and associated freshwater regimes between ~ 9.0 and 8.0 ka. They include (1) background deglacial meltwater and limited iceberg export prior to ~ 8.8 ka; (2) a short-lived episode of marine intrusion, ice-shelf formation, and subsequent ice-shelf breakup accompanied by transient iceberg discharge; and (3) a prolonged, multi-phase freshwater release between ~ 8.2 and 8.0 ka linked to the final collapse of the Hudson Bay ice saddle and drainage of glacial Lake Agassiz–Ojibway. Notably, the duration of this final freshwater phase is coeval, within uncertainty, with the 8.2 ka climate anomaly recorded in Greenland ice cores, consistent with a causal connection. This refined stratigraphic framework demonstrates that freshwater forcing from Hudson Bay was temporally structured and temporally sustained, highlighting the importance of ice-margin geometry and meltwater routing in modulating early Holocene climate perturbations.