Glaciated Regions Research Articles

Understanding the atmospheric dynamics over high-altitude glaciated regions in the central Himalaya using high-resolution numerical simulations

Abstract The atmospheric dynamics over the higher Himalaya play a crucial role in controlling glacier variability and ultimately regulating downstream water availability. However, the paucity of station observations makes exploring these atmospheric dynamics challenging. To address these issues, we employed a high-resolution configuration of the Weather Research and Forecasting (WRF) model with a 2-km convection-permitting grid scale to simulate atmospheric variables over the central Himalaya. We analyze the atmospheric variables over three high-altitude glaciated regions, namely the Langtang, Rolwaling, and Everest regions, in the central Himalaya. The model reproduces precipitation and temperature seasonality well, with the model precipitation displaying better agreement with the station data and outperforming the satellite observations. Furthermore, we investigate the spatial variability of precipitation during the monsoon and winter seasons and explore the associated dynamics by computing the vertically integrated moisture transport (VIMT) and vertically integrated moisture flux divergence (VIMFD). The VIMT and VIMFD analysis reveal that the valleys that meridionally dissect the Himalaya transport the moisture from the Indo-Gangetic plains to the higher Himalaya, and the sharp rise in elevation results in moisture convergence and precipitation, with the results that the ridges and windward slopes accumulate more precipitation than the leeward slopes and valleys. The orographic effect on moisture convergence, cloud formation, and precipitation consequently controls the glacier energy balance. During the monsoon season, the enhancement of net radiation by thick monsoon cloud cover, coupled with added latent heat and reduced albedo from the dominant liquid precipitation below 5,000 m amsl, increases the melt energy, promoting glacier melt.

Ice thickness and bed topography of Jostedalsbreen ice cap, Norway

Abstract. We present an extensive dataset of ice thickness measurements from Jostedalsbreen ice cap, mainland Europe's largest glacier. The dataset consists of more than 351 000 point values of ice thickness distributed along ∼ 1100 km profile segments that cover most of the ice cap. Ice thickness was measured during field campaigns in 2018, 2021, 2022 and 2023 using various ground-penetrating radar (GPR) systems with frequencies ranging between 2.5 and 500 MHz. A large majority of the ice thickness observations were collected in spring using either snowmobiles (90 %) or a helicopter-based radar system (8 %), while summer measurements were carried out on foot (2 %). To ensure accessibility and ease of use, metadata were attributed following the GlaThiDa dataset (GlaThiDa Consortium, 2020) and follow the FAIR (findable, accessible, interoperable and reusable) guiding principles. Our findings show that glacier ice of more than 400 m thickness is found in the upper regions of large outlet glaciers, with a maximum ice thickness of ∼ 630 m in the accumulation area of Tunsbergdalsbreen. Thin ice of less than 50 m covers narrow regions joining the central part of Jostedalsbreen with its northern and southern parts, making the ice cap vulnerable to break-up with future climate warming. Using the point values of ice thickness as input to an ice thickness model, we computed 10 m grids of ice thickness and bed topography that cover the entire ice cap. From these distributed datasets, we find that Jostedalsbreen (458 km2 in 2019) has a present (∼ 2020) mean ice thickness of 154 ± 22 m and an ice volume of 70.6 ± 10.2 km3. Locations of depressions in the map of bed topography are used to delineate potential future lakes, consequently providing a glimpse of the landscape if the entire Jostedalsbreen melts away. Together, the comprehensive ice thickness point values and ice-cap-wide grids serve as a baseline for future climate change impact studies at Jostedalsbreen. All data are available for download at https://doi.org/10.58059/yhwr-rx55 (Gillespie et al., 2024).

Glacial lakes inventory and susceptibility assessment in the Alsek River Basin, Yukon, Canada

BackgroundThis study investigates glacial lake outburst floods (GLOFs) within the Alsek River Basin, Yukon, Canada, a region experiencing accelerated glacier retreat due to climate change. The formation and expansion of glacial lakes pose significant hazards to geomorphological and ecological systems, even in the absence of human infrastructure. Despite extensive research in other glaciated regions such as the Himalayas and Andes, the Canadian Cordillera remains understudied. This research aims to inventory glacial lakes and assess their susceptibility to GLOFs using remote sensing techniques and two distinct methodologies.ResultsA total of 590 glacial lakes were identified, with 57 in direct or indirect contact with glaciers, warranting a detailed susceptibility assessment. The study applied the glacier-focused methodology of Wang et al. (Mt Res Dev 31(2):122 (2011). https://doi.org/10.1659/mrd-journal-d-10-00059.1) and the lakespecific dynamics approach of Khadka et al. (Front Earth Sci 8(January):1–16 (2021). https://doi.org/10.3389/feart.2020.601288). Key findings include: High-Hazard Lakes: Lakes 22, 23, 133, 134, and 275 were consistently identified as high-hazard due to factors such as large glacier inputs, steep moraine dams, and rapid expansion rates. GLOF Events: Four GLOF events were confirmed between 2017 and 2019, with the most significant reducing Lake 21's area by over 80%. Comparative Analysis: The integration of both methodologies provided a comprehensive understanding, revealing complementary insights into glacier-driven and lake-specific GLOF triggers.ConclusionThe results underscore the critical role of glacier retreat and lake dynamics in driving GLOF hazards in the AlsekRiver Basin. The study highlights the importance of combining multiple assessment methodologies for robust hazard evaluation. Given the dynamic nature of glacial lakes and ongoing climate change, continuous monitoring and proactive hazard management strategies are essential to mitigate potential geomorphological and ecological impacts. This research contributes to the broader understanding of GLOFs in North America and underscores the need for similar assessments in other understudied glaciated regions.

Spring-water temperature suggests widespread occurrence of Alpine permafrost in pseudo-relict rock glaciers

Abstract. 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 °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.

Ocean warming drives immediate mass loss from calving glaciers in the high Arctic

Glaciers in the Arctic have lost considerable mass during the last two decades. About a third of the glaciers by area drains into the ocean, yet the mechanisms and drivers governing mass loss at glacier calving fronts are poorly constrained in part due to few long-term glacier-ocean observations. Here, we combine a detailed satellite-based record of calving front ablation for Austfonna, the largest ice cap on Svalbard, with in-situ ocean records from an offshore mooring and modelled freshwater runoff for the period 2018-2022. We show that submarine melting and calving occur almost exclusively in autumn for all types of outlet glaciers, even for the surging and fast-flowing glacier Storisstraumen. Ocean temperature controls the observed frontal ablation, whereas subglacial runoff of surface meltwater appears to have little direct impact on the total ablation. The seasonal warming of the offshore waters varies both in magnitude, depth and timing, suggesting a complex interplay between inflowing Atlantic-influenced water at depth and seasonally warmed surface water in the Barents Sea. The immediate response of frontal ablation to seasonal ocean warming suggests that marine-terminating glaciers in high Arctic regions exposed to Atlantification are prone to rapid changes that should be accounted for in future glacier projections.

Significant changes of area, length and terminus of Sikkim Himalayan glaciers within the Kanchenjunga national park from 1990 - 2022

In this study, we have investigated four glaciers, namely Zemu, Talung, Alukthang and Rathong within Kanchenjunga national park. This study evaluates physical and morphometric parameters (area, length, perimeter, area of accumulation zone, ablation zone length, snout position, thickness and specific mass balance) of multiple glaciers and to ascertain the poorly understood glaciers of western Sikkim region under Kanchenjunga national park. The principal objective of this research is to find out the changes of glacial mass and other physical parameters of the selected glaciers using multi sources digital elevation model data.Various techniques of statistics, including Mann-Kendall and Sen’s slope tests have been applied at different confidence interval. We have identified that climate change is responsible for the alterations of the physical characteristics of the glaciers. Result shows that during the study period, Zemu glacier has faced highest amount of deglaciation in terms of area (20.79 sq.km) along with maximum 30 meter elevation reduction, 24m increase of snout elevation and 200m retreat of terminus. Furthermore, it is observed that terminus of the each selected glaciers retreated during the study period. Rathong experienced maximum retreat rate, approximately 550m, and it is accompanied by a notable 163% increase in the ablation zone. Alukthang and Talung reduced their areas 0.56 and 4.06 sq.km respectively, along with 2.75m and 9.10m thickness respectively. Maximum 36.39m/y-1 flow rate has been observed over Zemu glacier. The flow rate of Talung, Rathong and Alukthang glacier is 26.4m/y-1, 34.1m/y-1, and 23.7m/y-1 respectively.

Multiple late Holocene glacier advances on the sub-Antarctic Kerguelen (49°S) islands: Evidence from a 1200 yr sediment core from a glacial threshold basin

Southern Ocean (SO) climate is rapidly changing because of global warming and regional climate feedback loops like shifts of the Southern Hemisphere (SH) westerly winds (SHW) and related Southern Annular Mode (SAM). Over the past decades, the former has been persistently positive, shifting the latter southwards: the ensuing changes in temperature and precipitation are linked to the rapid retreat of mid-latitude mountain glaciers. Beyond the short instrumental period, the long-term impact of this coupled SHW-SAM system on regional glaciers remains poorly constrained. To help close this gap, we reconstruct glacier advances from an outlet glacier on the sub-Antarctic Kerguelen (49°S, 69°E), an archipelago that is strategically located in an under-investigated region of the SHW core belt. Based on alternations between relatively organic and minerogenic mud detected using a multiproxy approach on a 1200-year-long sediment record from a glacial threshold basin, we document glacier advances between 1150 and 850, 820–620, 500–250 and 160–90 cal yr BP. Coincident glacier advances in adjacent regions like sub-Antarctic South Georgia and southern Patagonia, suggest that SO glaciers responded symmetrically to climate forcings during the past 1200 years. We attribute this synchronicity to shifting SAM-like conditions and associated temperature changes. We suggest that cold and negative SAM-like conditions, favourable for glacier growth on the Kerguelen and other SO land masses, dominated during much of this period. Furthermore, the findings presented here support the growing consensus for a two-phased regional expression of the Little Ice Age (LIA).

Regional ice flow piracy following the collapse of Midgaard Glacier in Southeast Greenland

Southeast Greenland contributes significantly to global sea level rise, with mass loss having increased by about 600% over the past 30 years due to enhanced melt and dynamic instabilities of marine-terminating glaciers. Accurate modelling of glacier dynamics is crucial to minimise uncertainties in predictions of future sea level rise, necessitating detailed reconstructions of long-term glacial histories. One key complexity in these models that is not well understood or documented is ice flow piracy, where ice is redirected between catchment basins, significantly influencing regional glacier dynamics and mass balance. Here, we document and characterise the collapse of Midgaard Glacier in Southeast Greenland using a multi-data approach, providing a 90-year record of the area’s complex glacial history. Initiated over 80 years ago, this collapse triggered catchment-scale dynamic changes in several neighbouring glaciers, impacting local glacial stability throughout the 20th century and into the present. Our analysis reveals that catchment-scale ice flow piracy can cause substantial disturbances in mass balance evolution and catchment reconfigurations, independent of climatic conditions. These findings underscore the importance of understanding long-term changes in complex glacier systems to make accurate predictions of future glacial mass loss and associated sea-level rise.

Сравнительная динамика отдельных ледников широтного трансекта (Кодар–Гималаи)

Landsat remote sensing data make it possible to analyze the state of nival-glacial objects in various areas of modern glaciation with a periodicity of up to 5 years. One of the indicative and well-decipherable characteristics of such objects is the open area of the glacier. The latitudinal transect from the northern glaciation regions of Southern Siberia to the Himalayas makes it possible to present the dynamics of glaciers on the example of individual glaciers of key regions from this perspective with a five-year periodicity. Along the transect, the dynamics of glaciers in the mountains is shown: Kodar, Barguzinsky Range, Baikal Range, Eastern Sayan (Topografov Peak and Munku-Sardyk massifs), Mongolian Altai, Tien Shan, Himalayas. An analysis of changes in the open part of the glaciers of some representatives of these mountains is given. Throughout the transect, glaciers shrink, but to varying degrees. There is a decrease in glaciers and an increase in the intensity of surface moraine armor to a greater extent in the northern part of the transect. Based on the data of remote sensing of the Earth (Landsat), a comparison of the dynamics of the selected glaciers Azarova (No. 20, Kodar), Urel-Amutis (Barguzinsky Ridge), Chersky (Baikal Range), Peretolchina (No. 31, Munku-Sardyk), Topografov (No. 18, Okinsky Ridge), Tsast-Ula (No. 8, Tsambagarav), Karlygtag (Tien Shan), Altyntag (No. 3, Kunlun) and Yubra (No. 30, Langtang) was carried out. From the mid-1970s, when Landsat imagery began, to the present day, glaciers have shrunk in area from 17 to 63 percent. The glaciers of the northern part of the transect are shrinking more smoothly compared to the southern part. In the southern part, there is a reduction and slowdown, and sometimes an increase in the open part of the glaciers with a periodicity of about 10 years. The Himalayan glacier has the most uneven dynamics. The rate of glacier shrinkage decreases from south to north of the transect. The Azarova glacier is shrinking at a rate of 0.007 km2/year, the Urel-Amutis glacier is shrinking at a rate of 0.005, the Chersky glacier is shrinking at a rate of 0.002, the Peretolchina glacier is shrinking at a rate of 0.012, the Topografov glacier is shrinking at a rate of 0.002, the Tsast-Ula glacier is shrinking at a rate of 0.056, the Altyntag glacier is shrinking at a rate of 0.013, the Karlyktag glacier is shrinking at a rate of 0.07, and the Yubra glacier is shrinking at a rate of 0.085.

Effective identification of debris-covered glaciers in Western China using multiple machine-learning algorithms

Debris-covered glaciers (DCGs) represent a substantial portion of global glaciers, but their automatic identification remains a challenge due to environmental complexity and glacier type variability. This study focuses on 30 glacial areas across Western China, representing continental, sub-continental, and maritime glaciers. Using four machine-learning algorithms—Random Forests (RF), Extreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), and Support Vector Machine (SVM)—we integrated multiple environmental variables, including surface reflectance, normalized indices, surface temperature (ST), and topography, to classify DCGs through a three-process approach. Process 1 distinguished overall ice/snow cover from other land features, while Processes 2 and 3, both building on results of Process 1, further separated ice from snow cover and differentiated debris from other land features, respectively. Results showed that RF generally outperformed the other algorithms, with median Matthews correlation coefficient (MCC) values exceeding 0.999 in Process 1 and reaching 0.612 and 0.784 in Processes 2 and 3, respectively, and the average MCC value for DCGs identification reached 0.819. Regional modeling significantly improved the accuracy of DCG identification in Processes 2 and 3, particularly in continental glacier regions, with a notable increase in MCC values. Additionally, the independent binary-class models outperformed the integrated multi-class model in Processes 2 and 3, further validating the necessity of process-specific modeling. Comparison with the GGI18 glacier inventory showed a high level of consistency with the DCGs identified by the optimal algorithms, with an R2 value of 0.971. Despite uncertainties in maritime glacier regions, the proposed method demonstrates robustness and high spatiotemporal generalization. This approach, combining machine learning and environmental variables, offers a reliable tool for automated DCG identification and can significantly aid future glacier inventory compilation and monitoring efforts.

A century of variability of heatwave-driven streamflow in melt-driven basins and implications under climate change

AbstractMeltwater runoff from snow and glaciers in high mountain regions supports the water needs of hundreds of millions of people, but extreme events such as heatwaves modify the timing and magnitude of water available for downstream communities and ecosystems. The streamflow response to heatwaves depends strongly on heatwave timing and temperature, and the amount of snow and glacier ice available to melt. However, as ongoing climate change continues to alter both seasonal melt patterns and the frequency and intensity of heatwaves, it is not well understood how such streamflow responses will evolve relative to the seasonal cycle of streamflow. We address this knowledge gap by using long-term meteorological and hydrological datasets to characterize spatial and temporal heterogeneity in the streamflow sensitivity to heatwaves at six basins with >80 years of observations in Western Canada. We use years with earlier freshets and less snowfall as proxies of anticipated climate change, and apply a metric to describe how the streamflow sensitivity to heatwaves varies across years with different hydro-climatological characteristics. We find that in future proxy years relative to baseline years, nival streamflow is more sensitive to early spring heatwaves but less sensitive to late spring and summer heatwaves. Relative to baseline years, late spring heatwaves in future proxy years generate a smaller fraction of peak streamflow that is diminished as the freshet progresses. Our findings imply that future heatwave-driven peak flows in spring may be lessened by the diminished streamflow sensitivity to heatwaves in late spring, but this may be partially offset by excess melt during future heatwaves that are longer and hotter.

ТЕСТИРОВАНИЕ ВОЗМОЖНОСТЕЙ МЕТОДИКИ ОПЕРАТИВНОГО МОНИТОРИНГА ГОРНО-ЛЕДНИКОВЫХ СИСТЕМ

The article considers the possibilities of assessing the glaciation area of ​​the Northern Ile and Ile-Kungey glacier systems based on monitoring data from a limited sample of test glaciers. During testing in each of the mentioned glacier systems, based on the data on the area of ​​two samples of 10 glaciers, their total sample (20 glaciers) and their share in the total area of ​​glaciers in each of the named glaciation regions, the area of ​​glaciers of the corresponding glacier system was calculated. According to the testing results, the values ​​of the correlation coefficient of the calculated and actual (based on the results of glacier cataloguing) values ​​of the glaciation area for the three mentioned glacier samples were 0.99, 0.98, and 0.99 for the Northern Ile glacier system and 0.99, 0.97, and 0.99 for the Ilei-Kungey, respectively. The testing results leave no doubt about the possibility of operational monitoring of the glaciation area dynamics of mountain glacier systems based on the data on the area of ​​a limited sample of glaciers of the corresponding glacier system with an error of no more than ±5 %. According to the testing results, the calculated values ​​of the glacier area of ​​the considered glacier systems in 88 % of cases were less than 5% of the actual values, and only in 4 cases out of 33 (12 %) they exceeded this threshold, with an average deviation of the calculated data from the actual values ​​of less than 2 % and the largest calculation errors of 7.8 and -9.6 %. This indicates the high efficiency of the method of operational monitoring of mountain glacier systems. It allows to rapidly (with a repeatability from once every few years to annually) assess the loss of perennial ice in the considered glacier system and the contribution of glacial meltwater to the formation of river flow. Which, in its turn, is a good basis for the corresponding modeling of current and predicted changes.

Water quality assessment of Upper Ganga and Yamuna river systems during COVID-19 pandemic-induced lockdown: imprints of river rejuvenation.

Clean river water is an essential and life-sustaining asset for all living organisms. The upper Ganga and Yamuna river system has shown signs of rejuvenation and tremendous improvement in the water quality following the nationwide lockdown due to the coronavirus pandemic. All the industrial and commercial activity was shut down, and there was negligible wastewater discharge from the industries. This article addresses the water quality assessment from the study area, which is based on the original data of physical parameters, major and trace elements, and stable isotopes (hydrogen and oxygen) systematics during the nationwide lockdown. The impact of the lockdown could be seen in terms of an increase in dissolved oxygen (DO). Water samples were collected from the Upper Ganga and Yamuna river basins (Alaknanda, Bhagirathi, and Tons rivers) during an eight-week lockdown in Uttarakhand, India. We discussed the signs of rejuvenation of riverine based on physical parameters, major ions, trace elements, isotopic ratios, and water pollution index (WPI). Results reveal that the water quality of the entire upper basins of the Ganga has significantly improved by 93%, reflecting the signs of self-rejuvenation of the rivers. Multivariate analysis suggests a negative factor loading for an anthropogenic element ( ), implying that they contribute little to the river water during the lockdown. Further, bicarbonate ( ) is a dominant element in both river basins. The geochemical facies are mainly characterized by the ( ) type of water, suggesting that silicate rock weathering dominates with little influence from carbonate weathering in the area. The positive factor loadings of some cations, like , , and reflect their strong association with the source of origin in the lockdown phases. Stable isotopic reveals that the glaciated region contributed the most to the river basin, as evidenced by the low d-excess in riverine water compared to anthropogenic contributions. Rivers can self-rejuvenate if issues of human influence and anthropogenic activities are adequately resolved and underline our responsibility for purifying the ecosystem. We observed that this improvement in the river water quality will take a shorter time, and quality will deteriorate again when commercial and industrial activity resumes.

Reconciled estimation of Antarctic ice sheet mass balance and contribution to global sea level change from 1996 to 2021

AbstractThe Antarctic Ice Sheet (AIS) has been losing ice mass and contributing to global sea level rise (GSLR). Given its mass that is enough to cause ∼58 m of GSLR, accurate estimation of mass balance trend is critical for AIS mass loss monitoring and sea level rise forecasting. Here, we present an improved approach to reconciled solutions of mass balance in AIS and its regions from multiple contributing solutions using the input-out, altimetric, and gravimetric methods. In comparison to previous methods, such as IMBIE 2018, this approach utilizes an adaptive data aggregation window to handle the heterogeneity of the contributing solutions, including the number of solutions, temporal distributions, uncertainties, and estimation techniques. We improved the regression-based method by using a two-step procedure that establishes ensembled solutions within each method (input-output, altimetry, or gravimetry) and then estimates the method-independent reconciled solutions. For the first time, 16 contributing solutions from 8 Chinese institutions are used to estimate the reconciled mass balance of AIS and its regions from 1996 to 2021. Our results show that AIS has lost a total ice mass of ∼3213±253 Gt during the period, an equivalent of ∼8.9±0.7 mm of GSLR. There is a sustained mass loss acceleration since 2006, from 88.1±3.6 Gt yr−1 during 1996–2005 to 130.7±8.4 Gt yr−1 during 2006–2013 and further to 157.0±9.0 Gt yr−1 during 2014–2021. The mass loss signal in the West Antarctica and Antarctic Peninsula is dominant and clearly presented in the reconciled estimation and contributing solutions, regardless of estimation methods used and fluctuation of surface mass balance. Uncertainty and challenges remain in mass balance estimation in East Antarctica. This reconciled estimation approach can be extended and applied for improved mass balance estimation in the Greenland Ice Sheet and mountain glacier regions.

Ice Darkening on Turner Glacier in Auyuittuq National Park, Nunavut

The glaciers of the Canadian Arctic are currently the third largest contributor to global sea level rise due to enhanced Arctic warming driving increased glacier melt and runoff (Zemp et al., 2019). Recent modelling suggests that the glaciers of the southern Qikiqtaaluk region, specifically Baffin and Bylot Islands, are 70% more sensitive to 1°C of warming (Brice et al., 2018). However, these studies lack field-based data to contextualize the drivers of glacier change in this region. Light absorbing particles (LAPs) such as dust, ash, and algae lower the albedo of snow and ice, which is the fraction of light a surface reflects, leading to an increase in the absorption of incoming radiation (Aubry-Wake et al., 2022). On glaciers in western Canada (Engstrom et al., 2022), the European Alps (Di Mauro et al., 2020) and south-western Greenland (Cook et al., 2020), positive feedback mechanisms have been discovered where summer snow and ice melt, augmented by LAPs, leads to the localized release of nutrients in ice and the subsequent enhanced growth of algae. Preliminary remote sensing analysis revealing a dark purple hue on glaciers in the Akshayuk Pass region of Auyuittuq National Park in Baffin Island, NU indicate these processes are likely occurring. The question of how this phenomenon is impacting glacier albedo, and therefore glacier melt which has implications for mass balance and regional sea level rise in the Canadian High Arctic has yet to be answered. Field-based sampling of LAPs on Turner Glacier, characterized through light microscopy and scanning electron microscopy, combined with in-situ hyperspectral spectroradiometer measurements (320nm-1100nm) of the sampled LAPs, and fine resolution (1cm) UAV surveys of sampling sites, are integral to develop a field-calibrated remote sensing approach to monitor LAP accumulation on the glacier surface and to assess the associated melt potential.

First results of the polar regional climate model RACMO2.4

Abstract. The next version of the polar Regional Atmospheric Climate Model (referred to as RACMO2.4p1) is presented in this study. The principal update includes embedding of the package of physical parameterizations of the Integrated Forecast System (IFS) cycle 47r1. This constitutes changes in the precipitation, convection, turbulence, aerosol and surface schemes and includes a new cloud scheme with more prognostic variables and a dedicated lake model. Furthermore, the standalone IFS radiation physics module ecRad is incorporated into RACMO, and a multilayer snow module for non-glaciated regions is introduced. Other updates involve the introduction of a fractional land–ice mask, new and updated climatological data sets (such as aerosol concentrations and leaf area index), and the revision of several parameterizations specific to glaciated regions. As a proof of concept, we show first results for Greenland, Antarctica and a region encompassing the Arctic. By comparing the results with observations and the output from the previous model version (RACMO2.3p3), we show that the model performs well regarding the surface mass balance, surface energy balance, temperature, wind speed, cloud content and snow depth. The advection of snow hydrometeors strongly impacts the ice sheet's local surface mass balance, particularly in high-accumulation regions such as southeast Greenland and the Antarctic Peninsula. We critically assess the model output and identify some processes that would benefit from further model development.

Determinants of microbial community structure in supraglacial pool sediments of monsoonal Tibetan Plateau.

Supraglacial pools are prevalent on debris-covered mountain glaciers, yet only limited information is available on the microbial communities within these habitats. Our research questions for this preliminary study were: (1) What microbes occur in supraglacial pool sediments of monsoonal Tibet?; (2) Which abiotic and biotic habitat variables have the most influence on the microbial community structure?; and (3) Does microbial composition of supraglacial pool sediments differ from that of glacial-melt stream pool sediments? We collected microbial samples for 16S rRNA sequencing and invertebrates for enumeration and identification and measured 14 abiotic variables from 46 supraglacial pools and nine glacial-melt stream pools in 2018 and 2019. Generalized linear model analyses, small sample Akaike information criterion, and variable importance scores were used to identify the best predictor variables of microbial community structure. Multi-response permutation procedure (MRPP) was used to compare taxa composition between supraglacial pools and stream pools. The most abundant phyla in supraglacial pool sediments were Proteobacteria, Actinobacteria, Bacteroidota, Chloroflexi, and Cyanobacteria. Genera richness, indicator genera richness, and Polaromonas relative abundance were best predicted by Chironomidae larvae abundance. Angustibacter and Oryzihumus relative abundance were best predicted by pH, Acidiphilium relative abundance was best predicted by turbidity, and Sphingomonas relative abundance was best predicted by glacier zone. Taxa composition was similar between supraglacial and stream pools at the class, genus, and ASV taxonomic levels. Our results indicate that Chironomidae larvae may play a keystone species role in shaping bacterial communities of supraglacial pools on debris-covered glaciers.IMPORTANCEGlacier meltwater habitats (cryoconite holes, supraglacial pools, supraglacial ponds and lakes, glacial streams) and their biota have not been well-studied, especially on debris-covered glaciers in temperate monsoonal regions. Our study is the first to document the microbial community-habitat relationships in supraglacial pools on a debris-covered glacier in Tibet. Microbial genera richness, indicator genera richness, and Polaromonas relative abundance declined with increasing larval Chironomidae abundance, which is a novel finding that highlights the importance of larval insects in structuring microbial communities in supraglacial pools.

Using Iron Stable Isotopes to Quantify the Origins of the Cryoconite Iron Materials in Western China and Exploring Controlling Factors

AbstractIron (Fe) has profound impacts on Earth's ecosystem and global biogeochemical cycles. Fe deposited onto glacier surfaces reduces snow and ice albedo, thereby accelerating glacier melting, and supplying downstream ecosystems with dissolved Fe. However, the origins of atmospheric Fe deposition in glacier regions of western China remain unclear. This study presents novel insights into Fe isotopic composition (refer to δ56Fe) and origins, gained from geochemical analysis of large‐scale cryoconite samples collected from glaciers in western China, which encompass the Tibetan Plateau (TP) and the Tianshan Mountains. Results showed that cryoconite δ56Fe ranged from −1.06 ± 0.07‰ to 0.33 ± 0.04‰, regardless of their concentration. Moreover, anomalous δ56Fe values deviating significantly from the upper continental crust values (with an average of 0.09‰) were detected, indicating a significant impact of anthropogenic Fe materials on the investigated glaciers. This impact was particularly prominent in the margin regions of the TP and its surroundings, but was less apparent in the interior and southern of the plateau. Using MixSIAR isotope mixing model, we determined that coal combustion and other anthropogenic combustion sources (such as liquid fuel combustion and steel smelting) contributed to cryoconite Fe in the range of 6.9%–43.1% and 0.8%–23.4%, respectively. Among these, coal combustion was the predominant anthropogenic source of cryoconite Fe in western China's glaciers. Compared with other sink areas in the Northern Hemisphere, glaciers in western China are obviously affected by anthropogenically sourced Fe. This study has significant implications for understanding glacier‐fed downstream ecosystems and the regional biogeochemical cycle.

The Impact of Glacial Shrinkage on Future Streamflow in the Urumqi River Source Region of Eastern Tien Shan, Central Asia

Understanding changes in runoff due to climate variations in glacier-dominated headwaters is key to managing water resources and dryland watersheds effectively and rationally. The continuous glacier shrinkage caused by climate warming has significantly impacted the water supply and ecological systems in the vast arid regions of Central Asia, attracting extensive public concern. The study results indicate an increase in total runoff at the Urumqi River source region during both the baseline (1997–2016) and mid-century (2040–2059) periods, encompassing rain, glacier meltwater, and snowmelt components. Compared to the baseline period, the temperature increases by the mid-century under the three climate scenarios (SSP1−26, SSP2−45, and SSP5−85) range from 0.98 to 1.48 °C. In this region, during the period from 1997 to 2016, glacier meltwater was the dominant component of runoff, comprising 42.10–43.79% of the total, followed by snowmelt at 29.64–30.40% and rainfall contributions of 26.56–27.49%. Additionally, glacier storage in this typical catchment responds quickly to temperature fluctuations, significantly impacting runoff. The Urumqi River source region’s runoff exhibits heightened sensitivity to these temperature shifts compared to precipitation effects. We hypothesized three glacier coverage scenarios: unchanged at 100% glaciation, reduced by half to 50%, and fully retreated to 0% glaciation. Analysis of these scenarios demonstrated that glaciers are pivotal in runoff formation. Under the SSP1−26, SSP2−45, and SSP5−85 climate scenarios, glaciers contributed additional runoff increases of 51.61%, 57.64%, and 62.07%, respectively. Generally, glaciers play a critical role in supplying water in dry areas. Thus, accurately forecasting future water resource shifts in high-altitude glacier regions is crucial for downstream water resource management and utilization.

Altimetry-based ice-marginal lake water level changes in Greenland

Greenland holds over 3300 ice-marginal lakes, serving as natural reservoirs for outflow of meltwater to the ocean. A sudden release of water can largely influence ecosystems, landscape morphology, ice dynamics and cause flood hazards. While large-scale studies of glacial lake outburst floods (GLOFs) have been conducted in many glaciated regions, Greenland remains understudied. Here we use altimetry data to provide the first Greenland-wide inventory of ice-marginal lake water level changes, studying over 1100 lakes from 2003–2023, revealing a diverse range of lake behaviors. Around 60% of the lakes exhibit minimal fluctuations, while 326 lakes have drained, collectively contributing to 541 observed GLOFs from 2008–2022. These GLOFs vary substantially in magnitude and frequency, with the highest concentration observed in the North and Northeast regions. Our results show substantial annual differences in the number of GLOFs with a notable peak in 2019, coinciding with a year marked by extreme runoff. Our method detected a 1200% increase in the number of draining lakes compared to existing historical databases. This highlights a large underreporting of GLOF events and emphasizes the pressing need for a deeper understanding of the mechanisms behind and the consequences of these dramatic events.