Meltwater from Andean glaciers sustains river flow heavily relied on by ecosystems and communities downstream, particularly during periods of drought. However, contemporary rates of glacier recession in the Andes are accelerating and the yield of freshwater from the high mountain environment here is forecast to decline in coming decades, increasing water stress in the region. Water resource management policies rely on robust hydrological and glacier modelling, which themselves require accurate, long-term records of glacier ice loss rates. Prior to the contemporary satellite era (2000-today), records of glacier mass balance are patchy in the Andes, with available data lacking temporal resolution or covering small glacier samples and our knowledge of glacier behaviour during this period can be improved. Here, we have assembled geodetic glacier mass balance records for 10 glacierised river catchments containing ~3200 glaciers and spanning different climatic zones between 9°S (Rio Santa) and 50°S (Rio Santa Cruz). We have generated glacier surface elevation change data using DEMs generated from regional aerial photography surveys, from three archives of declassified American spy satellite imagery (Corona KH4, Hexagon KH9 mapping camera and Hexagon KH9 panoramic camera) and from contemporary optical stereo archives (ASTER). Our geodetic time series captures considerable inter-catchment variability in glacier mass loss rates across different climatic zones, but clearly indicates accelerating glacier mass loss rates throughout the Andes since the 1960s. These results will be used to calibrate glacier and hydrological models which will simulate meltwater flux from the same 10 catchments towards 2150 as part of the NERC Highlights Project ‘Deplete and Retreat: the Future of Andean Water Towers’.
How to cite: King, O., McNabb, R., Ghuffar, S., Falaschi, D., Dussaillant, I., Carrivick, J., Bhattacharjee, S., Davies, B., and Ely, J.: Andean glacier mass balance through the last six decades, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16893, https://doi.org/10.5194/egusphere-egu25-16893, 2025.
Central Asia hosts a high density of surge‑type glaciers (locally known as pulsating), which exhibit heterogeneous surge characteristics and poorly understood driving mechanisms. Historical monitoring of glacier dynamics in the region is scarce, particularly in the transitional area of the Hissar‑Alay (Pamir-Alay): there, as few as five surging glaciers are reported in existing inventories since the 1970s, and only the Abramov glacier pulsation of 1972 was studied in situ. However, a high prevalence of pulsating glaciers was postulated by Glazirin and Schetinnikov (1980), who used a Bayesian classification model of glacier morphology to predict around 200 occurrences in the Hissar‑Alay – almost 25% of the investigated sample.
Here, we systematically investigate pulsating behavior of glaciers in the Hissar-Alay, using a newly compiled dataset of optical satellite imagery from 1964 to present. We include data from film-based reconnaissance satellites (Key Hole program), SPOT 1 to 7, RapidEye, and Pléiades: these provide superior spatial resolution and temporal coverage compared to the commonly used Landsat and ASTER datasets.
Our analysis reveals asynchronous terminus advances and surge‑like patterns of ice thickness, within an overall context of mass loss. These findings confirm the occurrence of widespread glacier pulsation in the region, despite challenges in the differentiation of actual surge events from glacier advances. We note that existing inventories of surge-type glaciers are highly incomplete and biased towards larger glaciers. The model of Glazirin and Schetinnikov (1980) accurately predicted pulsating behavior at several previously unobserved glaciers; however, we also find a comparable number of misclassifications (both false positive and false negative), confirming that glacier morphology is an imperfect predictor of surging behavior.
Pulsations can induce rapid changes in glacier geometry and surface properties: these may undermine representativity of the computed glacier‑wide mass balance trends, including at reference glaciers like Abramov. Frequently updated topographic data are essential for large-scale modeling and geodetic studies in the region. However, even at pulsating glaciers, point measurements of mass balance remain valuable for calibration and validation of energy and mass balance models. Further investigation of spatio-temporal patterns of the found glacier pulsations will contribute to a better understanding of the drivers of surge behavior in Central Asia.
How to cite: Mattea, E., Barandun, M., Bhattacharya, A., Dehecq, A., Ghuffar, S., and Hoelzle, M.: Six decades of satellite remote sensing reveal widespread glacier pulsations in the Hissar-Alay (Central Asia), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9212, https://doi.org/10.5194/egusphere-egu25-9212, 2025.
Glacier flow is a sensitive indicator of mass balance and dynamics. Monitoring changes in glacier flow at high temporal resolutions enables understanding of the glacier’s sensitivity to short term climate variability. Previous studies have found that the glaciers in High Mountain Asia (HMA) are in tendency slowing down concomitant to losing mass at an accelerating rate. However, only few investigated seasonal velocity variations and the difference between debris-covered and debris-free glaciers flow dynamics. We focus on four debris-covered and four debris-free glaciers across HMA, which have different climates, glaciological, topographic and terminating environments. The four debris-covered glaciers include Kekesay, Satopanth, Khumbu and Xibu glaciers. The four debris-free glaciers include Tuyuksu, Abramov, Petrov and Yanong glaciers. Sentinel-1 and -2 images were selected to calculate the glacial velocities using the feature tracking module provided by CARST (Cryosphere And Remote Sensing Toolkit) (Zheng et al., 2021). We then developed a novel statistical method to extract the seasonally resolved glacial velocity time series. We found clear seasonal signals in the velocities for some of the glaciers and suggest that changes in the subglacial drainage system are driving the seasonal variations in velocities. This mechanism will likely continue in the future due to increased surface melt rates and changes in precipitation patterns across HMA. We also highlight that icefalls may alter the glaciers dynamics by blocking the development of subglacial drainage channels, and thus seasonal propagation of velocities. Our novel methodology enables further understanding of short term dynamics of debris-covered and debris-free glaciers, which is crucial to capture in order to study the response of glaciers today, and in the future to climate change in HMA.
Zheng, W., Durkin, W. J., Melkonian, A. K., & Pritchard, M. E. (2021, March 9). Cryosphere And Remote Sensing Toolkit (CARST) v2.0.0a1 (Version v2.0.0a1). Zenodo. http://doi.org/10.5281/zenodo.3475693
How to cite: Baldacchino, F., Bolch, T., and Zheng, W.: Investigating seasonal velocity variations of debris-covered and debris-free glaciers in High Mountain Asia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4317, https://doi.org/10.5194/egusphere-egu25-4317, 2025.
Glacier AX010 in the Shorong region is an iconic glacier in the Nepal Himalaya, observed since 1978. We conducted a drone photogrammetry survey in November 2023 and evaluated its volume change since 2008 as –1.3 m yr–1, one of the fastest (and accelerating) shrinking rates in the Himalayas. We reconstructed the annual mass balance using the ERA5 reanalysis climate data and a glacier mass balance model, GLIMB. We first evaluated the ERA5 meteorological variables with our recent in-situ observational data of a nearby site (2022-2023). Secondly, we calibrated the ERA5 precipitation to yield the observed geodetic mass balance and reconstructed the annual mass balance over the past 83 years (1940-2023). The estimated mass balance and calibrated temperature were validated with the observational data in the 1970s and 1990s. We also estimated the ideal temperature by which the glacier could maintain equilibrium states. Trend and breakpoint analyses revealed that the temperature warming and glacier shrinkage started in the mid-1970s while precipitation has been rather stable throughout the entire period. These results suggest that temperature warming is the main driver for the glacier shrinkage.
How to cite: Fujita, K. and Kayastha, R. B.: Finding the turning point and main driver of a disappearing Himalayan glacier, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13997, https://doi.org/10.5194/egusphere-egu25-13997, 2025.
Glaciers in México have been present for the last decades on the highest mountains of México: Iztaccíhuatl,Popocatépetl and Citlaltépetl.
In 1964 the size of twelve glaciers was measured at Iztaccíhuatl volcano using aerial photographs resulting in an extension of 1.4 km2. At the time of this review, El Pecho is the only remaining glacier on this mountain which exceeds the projections proposed earlier. Although much of the glacial retreat is related to climate change, in situ observationssuggest that geothermal heat fluxes and hydrothermal flows in the crater area should also be considered.
About the glaciers of Popocatépetl the glacial area in 1964 was 0.72 km2 and consisted of three glaciers. Before 1994, the retreat of glaciers was in the order of ~10,000 m2/year. On December 21, 1994, an eruptive period began atPopocatépetl volcano characterized by volcanic explosions alternating with lava dome construction-destruction phases.An increase in heat flow under the glacial ice, the fall of tephra on its surface, and pyroclastic flows that moved over the glacier surface, caused its irregular thinning, retreat and, in the final stage, its fragmentation between1994-2001.
At Citlaltépetl volcano the existence of 9 glaciers was established, covering an area of 2.04 km2. In 2007 they covered an area of 0.62 km2, and by 2019 the bedrock was exposed, faster than anticipated previously. The accumulation zone of the glacier system is not existent ever since. Exposure of the bedrock increases solar energy transference as heat to the adjacent ice and snow, causing an increasing melting. At the same time, it prevents the flow of ice towards the ablation zone, causing an accelerated retreat of the glacier front. So, the surface of the glacier in 2019 was ~0.46 km2, and the current extension for 2024 is only ~0.37 km2.
How to cite: Delgado Granados, H., Lorenzo, J. L., Julio Miranda, P., Cortes-Ramos, J., Ontiveros-González, G., and Soto, V.: ~70 years of glacier monitoring in Mexico, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14192, https://doi.org/10.5194/egusphere-egu25-14192, 2025.
With around 46 km2, Nevado Coropuna (NC, (15°32’S, 72°39’W; 6377 m) is the largest tropical icecap in the world. NC is situated on a stratovolcano structure with six peaks over 6000 meters, in the arid border of the Andean plateau, Southern Peru. NC is a vital source of freshwater for the communities within the Majes valley and for the vast irrigation plans located in the same valley and on the arid coastal strip. Here we present the 1955-2024 glacier surface evolution, which was retrieved from aerial photography and topographic maps for the initial stage in 1955 and from satellite imagery photogrammetry (SPOT, Worldview, PeruSAT-1 and Pleiades), backed by in-situ GPS-RTK measurements for the last 11 years.
Results show that the glacier lost an average of -0.15 m a-1 of ice between 1955 and 2013. The ice loss subsequently accelerated to a rate of -0.18 m a-1 between 2013 and 2018 and -0.44 m a-1 between 2018 and 2023. During the last year the ice loss rate has been -0.15 m a-1.
Ice loss has not been even across the glacier, but it primarily concentrated on the largest northern outlets, where it approached -1.9 m a-1 between 2018 and 2024 with a much lower ice reduction (-0.9 m a-1) in the southern outlets. Ice loss at the peaks is also reported, as a difference between a negligible ice change in the 1955-2013 timeframe contrasts a -0.7 m a-1 ice loss at the central part of the NC top plateau during the 2018-2024 timespan. The extensive debris-covered and rock glacier area features a much more stable behaviour, with ice loss/gain values within the error limit between 2013 and 2024. Likewise, the northwestern section of NC seems quite stable, possibly because of its comparatively higher elevation.
Results in NC show a continuous and consistent glacier retreat, but the mass loss pace is less accelerated than other Peruvian glaciers. Glaciers in the Vilcanota range, in the humid margin of the Andes, show a -0.5 m a-1 ice loss between 2000 and 2020 and there is an even stronger ice loss acceleration in the Central Andes area after 2013, with an average mass change of -1.067 m a-1.
How to cite: Pellitero Ondicol, R., Llanto Verde, J., Úbeda Palenque, J., and Atkinson Gordo, A. D.: Recent evolution and present situation of the world’s largest tropical icefield: the Nevado Coropuna (Peru). , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13743, https://doi.org/10.5194/egusphere-egu25-13743, 2025.
The Little Ice Age (LIA) is crucial for understanding the pre-industrial state of the cryosphere. Reconstructions often extend modern glacier inventories to LIA moraines, assuming minimal changes in high-altitude regions— a questionable premise for plateau icefields and other ice masses with top-heavy hypsometries. Using geomorphological mapping based on a wide range of high-resolution remote sensing data, including Sentinel-2 satellite imagery, we mapped the LIA extent of the Folgefonna icefield, Western Norway, in the highest attainable detail, distinguishing its geomorphological signature from earlier Holocene advances. A notable distinction was the contrast between densely vegetated pre-LIA surfaces and sparsely vegetated areas characteristic of the LIA. In steep topographical regions, talus cones outside the LIA boundary remained glacially undisturbed, while those within were often reworked into glacial drift, losing their original form. Other key indicators of the LIA boundary included fresh glaciofluvial fans below moraines. The identification of these distinguishing features may improve the accuracy of LIA reconstructions, which in turn may contribute to better glacier inventories and provide a more reliable foundation for assessing long-term glacier dynamics and changes in the cryosphere.
How to cite: Weber, P., Andreassen, L. M., Boston, C. M., and Tvede, A.: High-Resolution Glacier Mapping of Folgefonna, Western Norway, During Its ‘Little Ice Age’ Maximum and Subsequent Retreat, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20005, https://doi.org/10.5194/egusphere-egu25-20005, 2025.
Loss of glacier ice is contributing substantially to rising sea levels, and is negatively impacting up to 1.9 billion people globally who rely on meltwater for agriculture, drinking water, hydropower and other ecosystem services. Quantifying how glaciers are responding to ongoing climate change therefore has far-reaching implications, though a global observational assessment of this at an individual glacier scale is currently lacking.
Here, we leverage the Randolph Glacier Inventory v7.0 (RGI) dataset (baseline date: 2000), and imagery from the Sentinel-2 archive between 2020 and 2024 to establish the change in extent of the 181,402 small ice masses (area <= 2 km2) globally that are most vulnerable to climate change. We achieve this through developing a simple, highly automated approach to glacier extent identification in Google Earth Engine, analysing all cloud free imagery for the end of the melt season in each RGI region.
Our workflow derives thresholded Normalised Difference Snow Index (NDSI) glacier masks for each Sentinel-2 image where at least 95% of the RGI outline area is visible, with the area of each contiguous ice/snow patch calculated using object based connected component analysis. To minimise potential false positives associated with ephemeral snow cover, the resulting masks for each glacier are ranked smallest to largest by the largest ice patch observed, before a final glacier mask is obtained from the areas identified as ice in at least two out of the three top ranked images. Results are compared to custom ERA5-Land reanalysis baselines to highlight the likely climate drivers of these changes, while CMIP6 climate simulations are used to project potential future change.
Our results highlight that significant global glacier loss and fragmentation has already occurred since 2000, and is likely to continue with future projected warming. This demonstrates recent glacier vulnerability to climate change and that negative impacts arising from glacier loss will likely become more acute on timescales much shorter than a human lifespan. In the International Year of Glacier's Preservation, this analysis therefore has tangible use for establishing the sensitivity of glaciers to future climate change, communicating the global vulnerability of glaciers, and motivating calls for action.
How to cite: Lea, J., Brough, S., Chudley, T., Davies, B., Ely, J., King, O., Lamantia, K., Larocca, L., and Maussion, F.: Significant global loss and fragmentation of glaciers since 2000, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12214, https://doi.org/10.5194/egusphere-egu25-12214, 2025.
The rapid shrinkage of glaciers in recent years is a result of global warming. Long-term, worldwide observations of glacier mass balance—excluding the Antarctic and Greenland ice sheets—based on satellite data indicate that estimated mass loss between 2000 and 2019 accounts for about 21 ± 3% of observed sea-level rise (Hugonnet et al., 2021). The retreat of glaciers is expected to have major environmental and social impacts; therefore, predicting future glacier responses to a changing climate is crucial for anticipating and mitigating these impacts (Bolibar et al., 2022).
One way to quantify glacier responses to climate change is by monitoring the equilibrium line altitude (ELA) (e.g., Zemp et al., 2007). The ELA is defined as the spatially averaged altitude on the glacier surface where the climatic mass balance is zero at a given time. Moreover, it represents the lowest boundary of climatic glacierization (Ohmura et al., 1992). Hence, analyzing changes over time in glacier ELA is important for predicting future glacier behavior. However, field-based ELA observations (the glaciological method) are limited to only a few hundred glaciers due to the considerable labor and time required. It is also possible to detect the ELA using optical satellite images (Rastner et al., 2019), but these observations are often restricted at the end of the snowmelt season by cloud cover or the polar night.
In contrast, synthetic aperture radar (SAR) is largely insensitive to weather conditions and can observe glaciers regardless of solar illumination or cloud cover. Additionally, glacier zones (such as firn, superimposed ice, and ice) could be distinguished using SAR images (Barzycka et al., 2023). The lower boundary of the firn area is referred to as the firn line. In temperate glaciers without superimposed ice, the altitude of the newly formed annual firn line can be considered equivalent to that year’s ELA. However, the firn line does not exhibit strong year-to-year variability because the previous year’s firn remains in place. Instead, multiple consecutive years of negative (or positive) mass balance will cause the firn line to retreat (or advance). Consequently, firn line variations tend to smooth out annual fluctuations, revealing long-term trends of ELA (König et al., 2002).
In this study, we investigated long-term changes in the firn line altitude (FLA) of two temperate glaciers (Taku glacier, Kesselwandferner) with extensive ELA observation records using a time series of L-band SAR images (JERS-1, ALOS, and ALOS-2). We then compared the SAR-derived FLA with ELA recorded in the long-term. The results indicate that the FLA is consistent with long-term ELA changes, suggesting that the SAR-derived FLA effectively captures the long-term trends in glacier ELA.
How to cite: Arie, K. and Tadono, T.: The detection of long-term changes in the glacial firn line using L-Band SAR, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3010, https://doi.org/10.5194/egusphere-egu25-3010, 2025.
Temporal variations of glacier velocity estimation are essential to understanding glacier dynamics and predicting glacier hazards. Therefore, in the current study, the continuous glacier velocities were estimated from 2014 to 2023 in the Nathorstbreen Glacier System (NGS), Svalbard, where a recent surge event was observed. Also, the study identified and quantified the factors controlling variations in annual glacier velocity. Using Landsat 8 OLI imageries, Cossi-corr, an advanced Fourier-based image-matching tool, was utilized to estimate the velocity of the NGS. After that, a multivariate regression analysis preceded by the backward stepwise selection method to identify the controlling factors of annual glacier velocity variations, considering temperature, precipitation, snowfall, and terminus fluctuations. The result indicates that the highest and lowest average yearly velocity of NGS was observed in 2021 and 2018 with a magnitude of 0.86 ± 0.11 m/day and 0.34 ± 0.18 m/day, respectively. An overall decline in velocity was observed between 2014 and 2018, followed by a resurgence between 2020 and 2022 and a final decline in 2023. The terminus of the glaciers show retreat and advancement annually, with an overall retreat of 2.9 km through the study period. Terminus fluctuations were identified as a key driver of annual glacier velocity, with a strong correlation between terminus movement in one year and velocity changes in the next. A 100-meter retreat increased the following year’s yearly velocity by around 9.2 meters, whereas a 100-meter advancement of terminus slowed down the following year's velocity with the same magnitude.
How to cite: Kim, H.-C. and Guha, S.: Temporal Glacier Velocity Variations and Their Controlling Factors in the Nathorstbreen Glacier System, Svalbard, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3886, https://doi.org/10.5194/egusphere-egu25-3886, 2025.
Denman Glacier is one of the largest outlet glaciers in Antarctica. Despite its potential significance for sea level change, its geometry and dynamics remain poorly constrained, making predictions of its response to the changing climate challenging. Seismic signals arise from internal stress and interaction with the subglacial landscape, however, seismic methods are still an often underutilised tool for investigating glacial characteristics. In fact, seismology provides one of the few tools for directly observing the processes and properties that control outlet glacier stability and flow.
We present an overview of the seismic data acquired from a transect across Denman Glacier during the Denman Terrestrial Campaign (2023/24). The transect is located 50 km upstream from the grounding line, where the glacier is 13 km wide, and modelling studies suggest a very deep subglacial trough.
We employ a combination of passive and active seismic techniques to study the glacier’s geometry, internal structure, and dynamics. Our findings reveal constraints on the glacier's geometry, providing an independent view of the depth extent of the main trough. The recorded seismicity also offers preliminary insights into the glacier's dynamics, the baseline for the monitoring of changing environmental forcing.
How to cite: Stål, T., Reading, A. M., Askey-Doran, N., Cook, S., Gradl, J., Hudson, T., Kelly, I., Kulessa, B., Kupis, S., Lösing, M., Magyar, J., Manassero, M. C., Scheiter, M., Selway, K., Thompson, S., and Turner, R.: Seismicity of Denman Glacier: Constraints on Geometry and Dynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5279, https://doi.org/10.5194/egusphere-egu25-5279, 2025.
The High Mountain Asia (HMA) hosts the most significant number of glaciers outside the polar region, called the "Third Pole." Glacier meltwater is vital for 1.5 billion inhabitants in the HMA. The Yarlung Zangbo–Brahmaputra (YB), a transboundary river flowing from China through India and Bangladesh into the Bay of Bengal supporting more than 80 million people, is fed by over 15,000 pieces of glaciers. However, glacier melt contribution to the runoff in the YB by sub–basins is still unclear. In this study, we presented an updated glacier inventory for debris–free glaciers in the YB for 2020, calculated geodetic mass balance by glacier surface elevation difference, using NASADEM and GLO30 DEMs from 2000 to 2013, laser altimetry data from ICESat–2 from 2018 to 2023, and available elevation difference datasets from 2000 to 2020. Additionally, we studied nine individual glaciers to verify our geodetic glacier mass balance results with available in–situ observations and to better understand the glacier dynamics in the basin. Our study shows that (1) the glacier area decreased from 12,638.3±758.3 km2 in the 1970s to 9,081±12.09 km2 in 2020, with a loss of 28.15% of debris–free glacier area at –0.56 % a–1 in the past fifty years; (2) glacier mass balance (GMB) was –0.49 ± 0.02 m w.e.a–1 from 2000 to 2013, with glacier mass change (GMC) at –4.61 ± 0.41 Gt a–1; (3) based on ICESat–2 and GLO30 from 2013 to 2023, the GMB was –0.47 ± 0.02 m w.e.a–1, and GMC was –4.44 ± 0.38 Gt a–1; (4) the GMB was consistently negative in the YB from 2000 to 2020 at five–year intervals, with –0.36 m w.e.a–1 (–3.95 Gt a–1) in 2000 – 2005, and –0.64 m w.e.a–1 (–7.07 Gt a–1) in 2015 – 2020; (5) the GMB contribution to runoff increased from 0.05 % a–1 during 2000 – 2005 to 0.86 % a–1 during 2015 – 2020, with an average of 0.59% a–1 in the YB from 2000 to 2023.
How to cite: Ali, N., Ye, Q., Cuo, L., Zhang, X., Hu, Y., Ji, X., Lei, W., Junbo, W., and Liping, Z.: The glacier geodetic mass balance and its hydrological contribution to runoff in the Yarlung Zangbo-Brahmaputra basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5481, https://doi.org/10.5194/egusphere-egu25-5481, 2025.
The surface elevation of the Greenland Ice Sheet undergoes continuous changes driven by the interaction of surface mass balance processes and ice dynamics, each displaying distinct spatial and temporal characteristics. In this study, we utilize satellite and airborne altimetry data with high spatial (1 km) and temporal (monthly) resolution to examine these changes from January 2003 to August 2023. Our analysis highlights the complex and evolving elevation change patterns of Jakobshavn Isbræ (JI). Specifically, we document thinning near the JI terminus from 2003 to 2015, followed by thickening of approximately 25 meters between 2015 and 2018, thinning of around 20 meters from 2018 to 2022, and slight thickening during 2022–2023.
To validate these findings, we compare surface elevation changes derived from satellite and airborne altimetry with GPS observations from bedrock-based monitoring stations near the JI margins. These GPS stations capture bedrock displacement due to ongoing land uplift in response to current ice mass changes, with the glacial isostatic adjustment (GIA) signal removed. The GPS data, providing continuous daily estimates of mass changes, corroborates the intricate and evolving elevation change patterns observed in JI.
How to cite: Khan, S. A., Berg, D., Cheng, G., Morlighem, M., Barlatta, V., Seroussi, H., and Hassan, J.: Complex evolving elevation change pattern of Jakobshavn Isbræ during 2003-2023, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6055, https://doi.org/10.5194/egusphere-egu25-6055, 2025.
How to cite: Kupis, S., Stål, T., and Reading, A.: Seismic reconnaissance of firn structure in Denman Glacier region, East Antarctica, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6229, https://doi.org/10.5194/egusphere-egu25-6229, 2025.
High-altitude lakes across High Mountain Asia (HMA) are one of the critical freshwater reservoirs and sensitive indicators of climate change due to their remote locations and limited human disturbances. However, the ongoing climate change and enhanced glacier melt represent a substantial risk of outburst floods. We present an updated estimate of changes in water level of 239 lakes across HMA from 2010 to 2023 using satellite altimetry data from the CryoSat-2 mission. Examining lake levels, we observe a decline until 2015, followed by a rapid increase until 2023. About 42% of the lakes located above 4000 m a.s.l. are within glaciated catchments. Increased lake levels are particularly notable in glaciated catchments by 0.22 ± 0.01 m a-1, which is slightly faster than those in non-glaciated catchments (0.17 ± 0.01 m a-1). Elevated lake levels in glaciated catchments enhance the risk of glacial outburst floods.
How to cite: Hassan, J., Nielsen, K., Colgan, W., Kayastha, R., Khadka, M., and Khan, S.: Rising Lake Levels Across High Mountain Asia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7485, https://doi.org/10.5194/egusphere-egu25-7485, 2025.
Glacier albedo is a key driver of glacier energy and mass balance. In recent years, multi-annual firn and summertime snow cover has decreased on Alpine glaciers, exposing larger areas of ice at increasingly high elevations. This reduces glacier albedo and contributes to feedback mechanisms that lead to increased melt. To understand and better predict mass loss in former accumulation areas under conditions of rapid glacier recession, it is important to constrain the possible range of ice albedo that occurs in these newly snow and firn free regions, the duration of ice exposure, and the correlation and causal connection of these factors with ablation at point and glacier scales. Using a unique dataset from an on-ice weather station (3492 m.a.s.l.), ablation stakes, and remote sensing derived albedo, we provide a quantitative overview of albedo and ablation in the summit region of Weißseespitze, the high-point of Gepatschferner (Austria) from 2018 to 2024. We contextualize the observational data with modeling experiments quantifying the sensitivity of surface mass balance to the observed albedo. In the continuous time series of in situ albedo, the seasonal minimum is reached between late July and early September. From 2018 to 2021, minimum albedo values were about 0.30. In 2022, 2023, and 2024 the minima were considerably lower at 0.16-0.17. Prior to 2022, albedo dropped below 0.4 on 3 to 8 days per year. In 2022, 37 days of low albedo conditions (<0.4) were recorded. Ice ablation at the stakes generally increased with increased duration of ice exposure and ranged from zero ablation in years with mostly continuous summer snow cover (e.g. 2020) to more than -1.5 m w.e. in high-melt years like 2022 and 2024. Sentinel-2 derived albedo captures the range and variability of albedo measured in situ well and shows that ice albedo near the summit of Weißseespitze dropped to values similar to those of the surrounding rock in 2022. For average July-September conditions, an albedo decrease from 0.4 to 0.15 results in 10-15 mm w.e. of additional modeled surface melt per day. The impact of ice exposure on melt varies seasonally, with highest sensitivities early in the season. A five day period of very low albedo conditions (<0.2) results in 26% more modeled surface melt if it occurs in late July compared to early September. The albedo decrease at the AWS since 2022 may be related to the exposure and melting of impurity rich firn and ice layers and the accumulation of impurities at the surface, increased presence of meltwater, and the state of the weathering crust. Our extensive dataset sheds light on upcoming changes to be expected at the highest elevations of alpine glaciers in many regions worldwide and provides a starting point for further studies aimed at linking cause and effect of ice albedo variability across scales.
How to cite: Hartl, L., Covi, F., Stocker-Waldhuber, M., Baldo, A., Fugazza, D., DiMauro, B., and Naegeli, K.: Losing the accumulation zone: Exploring albedo and ablation in the summit region of Gepatschferner, Austria, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9169, https://doi.org/10.5194/egusphere-egu25-9169, 2025.
The Getz Glaciers, situated near the Amundsen Sea in West Antarctica, represent the third-largest source of freshwater discharge from the Antarctic Ice Sheet. Understanding the physical mechanisms driving ice loss in this region is essential for refining projections of future ice loss and its contributions to global sea-level rise. Subglacial hydrology has recently been recognized as a critical factor influencing long-term glacial mass balance. However, the inland regions of the Getz Glaciers remain relatively understudied compared to other parts of Antarctica. This study utilizes CryoSat-2 satellite altimetry data to detect active subglacial lakes across the Getz Glacier region from 2010 to 2024. The findings reveal a significant number of active subglacial lakes, indicative of vigorous meltwater generation, consistent with observations from other West Antarctic glaciers, such as the Thwaites Glacier and Ross Ice Stream. Further research is required to investigate the potential connections between subglacial hydrology, ocean circulation, and its impact on ice shelf destabilization.
How to cite: Kim, B.-H., Lee, C.-K., Lee, W. S., and Seo, K.-W.: Active subglacial lakes in the Getz glaciers revealed by CryoSat-2 radar altimetry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9283, https://doi.org/10.5194/egusphere-egu25-9283, 2025.
The retreat of tropical glaciers is a visible effect of climate change, which is evident in Peru. These glaciers are sensitive to global and local temperature increases, causing accelerated glacier mass loss. From 1962 to 2020, there has been a decrease in glacier cover at the national level, with a loss of approximately 1,280.95 km². This phenomenon significantly affects local ecosystems and water availability, putting at risk the supply of water for human consumption, agriculture and other essential activities, particularly during dry seasons.
The research was carried out on the Shallap and Llaca glaciers, located in the Cordillera Blanca in Ancash, Peru. The Shallap glacier is characterized by two clearly differentiated zones: one covered by debris and the other with a clean surface. While the Llaca glacier has a glacial tongue completely covered by debris which terminates in a proglacial lake. This distinction in the surface characteristics of both glaciers allows for detailed comparisons, providing insights into the role of supraglacial debris in modifying glacier melt rates, processes which have been rarely studied in the Peruvian Andes.
Repeat Unmanned Aerial Vehicle (UAV) imagery conducted in 2019 and 2024 allowed the calculation of mass and area changes of both glaciers, and the assessment of morphological changes between the time periods. Imagery was co-registered to reduce the planimetric errors in the Digital Elevation Models (DEMs).
Much lower mass losses were found over Shallap glacier in the debris-covered compared to clean ice zones, with the debris-covered zone retreating by a maximum of 36 meters, with an area loss of 8,257 m² (equivalent to -14,202 m³ of ice). On the other hand, the debris-free zone retreated by a maximum of 165 meters, with an area loss of 24,439 m², representing a volume of -61,160 m³. However, the Llaca glacier showed a maximum retreat of 122 meters, with an area loss of 21,144 m² (equivalent to -397,813 m³ of ice). This difference in volume loss compared to Shallap glacier, could be due to the presence of the proglacial lagoon, which is still in contact with Llaca glacier and that would be contributing to a greater glacial melting.
Another factor that modulates glacial behavior is the supraglacial debris layer, according to the results obtained from the loss of glacier volume considering the movement recorded between June and November 2024, it was observed that the debris layers of 1.5 cm and 5.5 cm were associated with ice losses of 3.6 m and 2.5 m, respectively. In contrast, the 33 cm and 50 cm thick debris layers showed considerably smaller ice losses of only 0.4 m and 0.2 m. It can be seen that the thicker the debris layer, the lower the ice thickness loss.
How to cite: Granados, H., Santiago, A., Curo, Y., Dávila, L., Celmi, G., and Fyffe, C.: Influence of the debris layer on the behavior of the Shallap and Llaca glaciers, Cordillera Blanca, Ancash, Peru, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14455, https://doi.org/10.5194/egusphere-egu25-14455, 2025.
Glacier inventories serve as critical baseline data for understanding and assessing past, current, and possible future conditions of the local, regional, and global environment. In this study we present a manually mapped inventory of glaciers in the sub-Antarctic Heard Island, for 1947, 1988, and 2019, derived from large-scale topographical maps (1:50,000), cloud-free medium-resolution SPOT, and high-resolution PLEIADES satellite orthoimages.
The total glacier area has reduced from 289.4±6.1 km2 in 1947 to 260.3±6.3 km2 in 1988, which further decreased to 225.7±4.2 km2 in 2019. The mean glacier area has also reduced from 10 km2 to 8.7 km2 and to 6.4 km2 respectively, during the same period. The rate of annual glacier area loss was almost doubled (−0.43% yr−1) in the second investigated period (1988-2019), then it was (−0.25% yr−1) in the first period (1947-1988). Glaciers on the eastern slopes has experienced much higher decrease and retreat rates than the rest of the glaciers. The maximum retreat we observed between 1947 and 2019 was ~5.8 km for the east-facing Stephenson Glacier.
The findings of our study may provide information on how glaciers on Heard Island respond to climate change, potentially reducing uncertainty for further climate and glaciological modelling in this sub-Antarctic region.
How to cite: Tielidze, L., Mackintosh, A., and Yang, W.: Glacier inventory of the sub-Antarctic Heard Island, Australian external territory, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10618, https://doi.org/10.5194/egusphere-egu25-10618, 2025.
Greenland’s peripheral glaciers and ice caps are particularly sensitive to a warming climate and often respond more rapidly to warming than the Greenland Ice Sheet. These smaller ice bodies also play a vital role in local ecosystems. End-of-winter distribution of snow cover is a key driver of glacier mass balance, but predicting snow accumulation in the complex glacier terrain is challenging due to the interplay of topography and wind that influences snowfall deposition and re-distribution. Accurate mass balance estimates must therefore rely on in-situ observations.
Here, we present a dataset of end-of-winter snow depths over A.P. Olsen Ice Cap (APO), northeast Greenland, derived from ground-penetrating radar (GPR) measurements over the period 2008-2024. Spanning a total profile length of 568 km collected over 12 survey years, this dataset combines a rare long-term time series of in-situ observations with extensive spatial coverage, offering exceptional insights into snow accumulation patterns. We use this dataset to i) assess the spatio-temporal distribution of snow accumulation over the 16-year period, and ii) evaluate the performance of a regional climate model, the Arctic reanalysis product CARRA, to simulate end-of-winter snow depths. Our findings provide insights into the utility of CARRA for filling spatial and temporal gaps in in-situ end-of-winter snow depth data, a key input parameter for surface mass balance models over A.P. Olsen Ice Cap and other peripheral glaciers.
How to cite: Rutishauser, A., Hillerup Larsen, S., Karlsson, N. B., Citterio, M., Binder, D., and Hynek, B.: 12 years of snow accumulation from ground-penetrating radar surveys on AP Olsen Ice Cap, northeast Greenland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12445, https://doi.org/10.5194/egusphere-egu25-12445, 2025.
The World Glacier Monitoring Service (WGMS) and its global network of collaborators maintain a comprehensive programme of ongoing glacier change, resulting in an unprecedented dataset that serves as an increasingly important basis for fundamental glacier research and various applications at local, regional, and global scales. Knowledge of glacier distribution and quantification of glacier change is crucial for assessing the impact of glacier shrinkage on regional freshwater availability, local geohazards, tourism, sites of cultural significance, and global sea levels. Therefore, glacier monitoring is essential for the development of sustainable adaptation strategies in regions wherever glaciers (still) exist.
In this presentation, we assess the status of glacier monitoring in each country in 2025 and compare it to the 2015 baseline (Gärtner-Roer et al., Mountain Research and Development, 2019). During this time, surface elevation changes derived from satellite data reached nearly global coverage. In addition, temporal but also spatial gaps could be filled by adding new glaciological in situ series thanks to data rescue efforts. For each country, we describe the number of observed glaciers and total number of observations available in the WGMS Fluctuations of Glaciers (FoG) database for the following observation types: front variation, glaciological surface mass balance, and geodetic surface elevation change. In addition, we review the availability of glacier outline inventories and the annual mass-balance trend in each country.
Finally, we discuss the role of glacier monitoring in international research and policy-making to place our results in the context of global climate-change monitoring. With the advent of new datasets, such as those derived from satellites, information on glaciers transcends national boundaries. However, limited funding often hampers the long-term monitoring of glaciers, regardless of data source. In view of the International Year of Glaciers’ Preservation in 2025 and the United Nations (UN) Decade of Action for Cryospheric Research in 2025–2034, we establish a 2025 baseline and make recommendations for the future of glacier research.
How to cite: Nussbaumer, S. U., Gärtner-Roer, I., Saibene, G., Welty, E., and Zemp, M.: National and global glacier monitoring efforts – a comparative assessment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13593, https://doi.org/10.5194/egusphere-egu25-13593, 2025.
Changing glaciers are definite indicators, warning lights, contemporary witnesses and memorials of climate change, as they are accessible beauties and related impacts on the environment, economies, and societies are relatively easy to understand. While these immediate impacts are mainly relevant on local and regional scales, related measures to preserve them need to be taken on the global scale. Therefore, the United Nations have declared 2025 the International Year of Glaciers’ Preservation (IYGP; https://www.un-glaciers.org) to raise global awareness of glaciers' importance and to ensure that those relying on them or affected by their vanishing have access to the necessary data and information services.
The World Glacier Monitoring Service (WGMS) – together with the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the World Meteorological Organization (WMO) – helped to coordinate the implementation of the international glacier year, the World Day of Glaciers (from 2025 on the 21st of March) and the United Nations Decade of Action for Cryospheric Research 2025−2034. The contributions have focused on the communication of the scientific basis by explaining the basic processes of glacier dynamics, giving insights into in-situ and remote-sensing techniques to quantify glacier changes and by presenting the latest numbers of glacier mass changes. The WGMS has been actively supported by its network of National Correspondents and Principle Investigators, who highlighted individual or regional glacier changes in workshops, exhibitions, and innovative outreach projects.
Based on the experiences gained so far from national and international outreach events, we want to carefully assess the effect and benefits of these science-based activities on the international glacier monitoring and beyond. This analysis should help to prepare upcoming activities during United Nations Decade of Action for Cryospheric Research 2025−2034 as well as negotiations with decision makers at various levels.
How to cite: Gärtner-Roer, I., Nussbaumer, S. U., and Zemp, M.: WGMS contribution to the International Year of Glaciers’ Preservation 2025 – experiences and first conclusions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14985, https://doi.org/10.5194/egusphere-egu25-14985, 2025.
The elevation bias due to signal penetration in bistatic InSAR DEMs is recognized as a main error source together with co-registration for estimating glacier mass balance with the DEM differencing method. For TanDEM-X DEMs, the elevation processed from X-band (9.65 GHz) SAR data can lie up to 4-8m lower than the actual snow/ice surface in alpine accumulation areas [1]. However, this bias can often be mitigated by differencing TanDEM-X acquisitions from the same season with unchanged SAR geometry, reducing penetration differences between DEMs. The relative importance of SAR signal penetration for accurate mass balance measurements also reduces with the length of the observation period.
Notably, methods have been developed to correct for SAR signal penetration bias, including estimating volumetric coherence and inverting it [2,3]. However, correction methods have rarely been tested and validated across entire TanDEM-X scenes with coincident ground truth measurements of the actual ice surface. [4] calculated signal penetration based on inversion of volumetric coherence on Union Glacier, Antarctica and validated the results against the optical REMA DEM mosaic over temporally stable surfaces.
A recent study on Aletsch Glacier has observed the elevation bias due to signal penetration in a time stamped TanDEM-X DEM by comparing it to a coincident DEM acquisition from Pléiades optical imagery [1]. Moreover, during an inter-comparison experiment on glacier elevation changes, airborne lidar validation DEMs were produced for Aletsch Glacier enabling a comparison of volumetric changes with TanDEM-X measurements [5].
We use these results to analyse the circumstances under which a signal penetration correction layer associated to the individual processed TanDEM-X DEMs can be used to generate bistatic X-band DEMs that reflect the actual ice/snow surface. We will assess the impact of a signal penetration correction on mass balance measurements similar to [6].
References
[1] Bannwart, Jacqueline, Livia Piermattei, Inés Dussaillant, Lukas Krieger, Dana Floricioiu, Etienne Berthier, Claudia Roeoesli, Horst Machguth, and Michael Zemp. 2024. “Elevation Bias Due to Penetration of Spaceborne Radar Signal on Grosser Aletschgletscher, Switzerland.” Journal of Glaciology, April, 1–15. https://doi.org/10.1017/jog.2024.37.
[2] Weber Hoen, E., and H.A. Zebker. 2000. “Penetration Depths Inferred from Interferometric Volume Decorrelation Observed over the Greenland Ice Sheet.” IEEE Transactions on Geoscience and Remote Sensing 38 (6): 2571–83. https://doi.org/10.1109/36.885204.
[3] Dall, Jørgen. 2007. “InSAR Elevation Bias Caused by Penetration Into Uniform Volumes.” IEEE Transactions on Geoscience and Remote Sensing 45 (7): 2319–24. https://doi.org/10.1109/TGRS.2007.896613.
[4] Rott, Helmut, Stefan Scheiblauer, Jan Wuite, Lukas Krieger, Dana Floricioiu, Paola Rizzoli, Ludivine Libert, and Thomas Nagler. 2021. “Penetration of Interferometric Radar Signals in Antarctic Snow.” The Cryosphere 15 (9): 4399–4419. https://doi.org/10.5194/tc-15-4399-2021.
[5] Piermattei, Livia, Michael Zemp, Christian Sommer, Fanny Brun, Matthias H. Braun, Liss M. Andreassen, Joaquín M. C. Belart, et al. 2024. “Observing Glacier Elevation Changes from Spaceborne Optical and Radar Sensors – an Inter-Comparison Experiment Using ASTER and TanDEM-X Data.” The Cryosphere 18 (7): 3195–3230. https://doi.org/10.5194/tc-18-3195-2024.
[6] Abdullahi, Sahra, David Burgess, Birgit Wessel, Luke Copland, and Achim Roth. 2023. “Quantifying the Impact of X-Band InSAR Penetration Bias on Elevation Change and Mass Balance Estimation.” Annals of Glaciology 64 (92): 396–410. https://doi.org/10.1017/aog.2024.7.
How to cite: Krieger, L., Ibarrola Subiza, N., Floricioiu, D., Fischer, G., and Abdullahi, S.: Assessing the TanDEM-X elevation bias due to SAR signal penetration for glacier mass balance measurements, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16658, https://doi.org/10.5194/egusphere-egu25-16658, 2025.
The Pamir Mountains are an important target of current research: they constitute a crucial mountain water tower that is highly vulnerable to future climatic, environmental, and social change; and they contain glaciers experiencing limited early 21st-century mass loss despite climate warming. Due to geopolitical factors, the in-situ records in the region were interrupted during this period, and current assessments of glacier volume and mass change in this region are highly uncertain. A global assessment of geodetic mass balance from ASTER images has suggested a change in the mass balance regime in the region toward declining glacier health, but its uncertainties are very high. In this study, we leverage high-resolution (<5m) optical stereo images that compensate for the scarcity of in-situ snow and glacier observation to provide a mass balance estimate entirely independent of the ASTER dataset.
We analyze high-resolution SPOT5, SPOT6, and Pléiades stereo satellite images acquired since the 2000s over the Sangvor glacierized catchment in the Pamir mountains as a case study. We adopt a stereo image analysis workflow from the Ames Stereo Pipeline to process these data, including coregistration and bias correction, and to remove erroneous artifacts such as jitter-induced undulations. In addition to approximating and subtracting the undulation errors using Fourier transforms, for the results with insufficient correction, we adopt an empirical method that calculates the average value of the error in the cross-track direction of the image from the estimated satellite orbit and directly subtracts the averaged error in each along-track direction. We evaluate the elevation change uncertainty based on the patch approach and then quantify glacier mass balance spanning twenty years over our study domain. In order to empirically estimate the error in the spatially averaged elevation change in the study area, we sampled the area into a certain area, calculated the median of the elevation change in the stable terrain, and then calculated the mean of the absolute difference of these tiled median errors. Finally, we compare our results to those derived from ASTER DEMs for this period. Our results demonstrate the potential of very high-resolution satellite imagery for snow and glacier monitoring despite the challenge of short-interval observations and highlight the value of multiple independent, high-quality geodetic mass balance estimates to resolve changes over shorter periods.
How to cite: Hagiwara, H., Miles, E., Jouberton, A., and Pellicciotti, F.: Glacier mass changes in the Western Pamirs 2003-2024 from high-resolution stereo satellite images, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17900, https://doi.org/10.5194/egusphere-egu25-17900, 2025.
Extensive databases of satellite imagery are now available and can be used to undertake assessments of the mass balance of glaciers. Previous studies have mapped the end-of-season snowlines (ESS) on glaciers from satellite imagery to find their snowline altitudes (SLA) and used these as proxies for the glacier equilibrium-li ne altitudes (ELA). This approach is advantageous because it can be implemented at a large scale and may employ automated methods. The veracity of using remotely measured SLAs as a proxy for in-situ measured ELAs however, has not yet been robustly demonstrated.
We have undertaken a systematic mapping of ESSs on 20 glaciers with existing measured mass balance records to determine the errors associated with remotely measured SLAs. Glaciers are selected from the World Glacier Monitoring Service (WGMS) Fluctuations of Glacier (FoG) database. For each ELA record, we identify the Landsat image closest in date to the original ELA measurement (where cloud cover is minimal) and the image with the highest altitude snowline for the year. For each image, the snowline is mapped, and its corresponding SLA is extracted from the ASTER Global Digital Elevation Map (ASTERGDEM). We find that the reliability of this method is variable, as it is often limited by satellite revisit periods, cloud cover, and late-summer snowfall events. We specifically investigate further the complexities associated with distilling the range of elevation values comprising a mapped snowline into a single elevation value, for example, taking the mean and median elevations along the full width of the glacier and within a fixed buffer of the central flowline and the effect patchy and irregular snowline segments might have on the calculations. Where snow cover is patchy, a greater length of snowline is mapped in order to trace the boundary than is required for smoother segments. This is regardless of whether it contributes a larger area of snow cover or not. Consequently, the SLA calculations are prone to oversampling from areas of irregular snow cover. These results highlight a need to better define the end-of-season SLA and how best to calculate it.
How to cite: Hallford, M., Rea, B. R., Mullan, D., Spagnolo, M., Sam, L., and Singh, S.: Complexities of Using Satellite Imagery for Defining Snowline Altitudes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19578, https://doi.org/10.5194/egusphere-egu25-19578, 2025.
Over the past two decades, glaciers in the Himalaya-Karakoram (HK) region have exhibited heterogeneous but accelerated mass loss. Factors driving this loss, such as atmospheric warming and snowfall variability, have been extensively studied by analyzing precipitation and air temperature data, often derived from meteorological reanalysis data. However, reanalysis data such as ERA5 exhibit significant biases and uncertainties, resulting in large spread in glacier mass balance estimates across studies. To address this, we propose to use thermal remote sensing data from the MODIS satellite, which provides glacier surface temperature (GST) at an 8-day temporal and 1 km spatial resolution.
This study leverages 24 years (2000–2024) of MODIS land surface temperature data to analyze GST characteristics, seasonality, and trends across HK subregions. Since temperature modulates glacier mass balance, remote-sensing-based GST is likely to be a superior dataset for mass balance modelling. We demonstrate this by obtaining a strong correlation (r: -0.47; p-value: 0.02) between GST and mass balance for ~6000 glaciers in the HK region. We also show that MODIS-derived GST outperforms ERA5 surface temperature when validated against in-situ surface temperature data measured on glaciers (R2: 0.88, RMSE: 3.57 °C vs. R2: 0.38, RMSE: 8.01 °C).
Our analysis of the spatiotemporal behaviour of GST reveals that during the ablation season, GST has been increasing at an average rate of +0.25 °C dec-1across the HK region, with the Eastern Himalaya experiencing the highest warming (+0.44 °C dec-1). Ablation months, August and September, exhibit more pronounced GST warming compared to other months. Comparisons between the decadal averages (2001-2010 vs. 2011-2020) indicate a marked increase in GST, on average +0.18 °C higher in the second decade across the HK subregions, with the Karakoram showing a threefold higher warming rate than others. Altitudinally, GST warming is strongest in mid-glacier areas (4300-5300 m), predominantly clean-ice zones, which warmed +0.30 °C more than debris-covered areas.
In the Eastern Himalaya, rising GST has significantly increased the annual positive GST area ratio (fraction of glacierised area with > 0 °C GST) by ~3% of total glacierised area, contributing to the region's steeper glacier mass loss than other subregions. Overall, the Eastern Himalaya stands out as a hotspot for GST warming, with significant increases annually, during the ablation season, and across altitudinal zones, making it highly vulnerable to persistent and accelerated glacier mass loss.
This study highlights the utility of satellite-derived GST for assessing glacier thermal states and their mass loss characteristics, offering valuable insights into glacier-surface-atmosphere interactions.
How to cite: Mandal, A. and Vishwakarma, B. D.: Glacier surface temperature warming in the Himalaya-Karakoram: Implications for glacier mass loss, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9239, https://doi.org/10.5194/egusphere-egu25-9239, 2025.
Glaciers terminating in lakes typically flow, thin and lose mass more rapidly than those that terminate on land. This is due to a range of thermomechanical processes exerted at the lake-ice interface, where lake waters drive melt-induced undercutting, enable flotation and facilitate calving. In Greenland, ice marginal lakes (IMLs) have increased in size and number over recent decades and now occupy more than 10% of the ice sheet margin. Despite this, very few observations of their effects on ice dynamics exist, meaning they remain largely unaccounted for in models of ice sheet change.
Here, we use ITS_LIVE ice surface velocity data and the How et al. (2021) IML inventory to compare the flow characteristics of 102 lake-terminating outlet glaciers and 102 neighboring land-terminating outlet glaciers across the Greenland Ice Sheet (GrIS) during 2017. We find that along-flow decelerations are much less pronounced at lake- versus land-terminating glaciers, and that some lake-terminating glaciers (n = 33) even speed up towards the ice margin. In turn, lake-terminating glaciers are on average 4.6 times faster than their land-terminating counterparts within the terminus region. Moreover, the fastest flowing glaciers are found to terminate in the largest lakes, suggesting that lake influence evolves with lake development. Ultimately, these observations demonstrate the capacity of IMLs to enhance the surface velocity of Greenlandic outlet glaciers, highlighting their potential to accelerate future mass loss from the GrIS.
How to cite: Harpur, C., Smith, M., Carrivick, J., Quincey, D., and Taylor, L.: Ice marginal lakes enhance outlet glacier velocities across Greenland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12360, https://doi.org/10.5194/egusphere-egu25-12360, 2025.
The glaciers of North Sikkim, located in the Central Himalaya, serve as crucial indicators of climate change, shedding light on cryospheric processes and hydrological impacts. This study utilizes feature tracking-based remote sensing techniques to analyze glacier velocity trends from 1990 to 2022, examining 679 glaciers categorized as clean glaciers (CG), debris-covered glaciers (DG), glaciers associated with lakes (GL), rock glaciers (RG), and smaller glaciers (SG, <0.5 km²). Landsat imagery reveals velocity values ranging from -20.17 m/year to 21.99 m/year, with a mean velocity of 0.49 m/year. spatial-temporal analysis identifies three velocity phases for the glaciers like moderate variability (1990–2000), stabilization (2001–2010), and acceleration (2011–2022). The latest phase shows a sharp rise in mean velocity to 0.75 m/year, correlating with increased warming trends. Smaller glaciers exhibited the highest climate sensitivity, with extreme velocities reaching 21.9 m/year, while debris-covered glaciers showed periodic accelerations exceeding 10 m/year in 1996 and 2022. Spatial analysis highlights the influence of glacier size and elevation, with higher-altitude glaciers (>5000 m) moving faster due to steeper gradients.
Class-wise analysis reveals distinct behaviors. Clean glaciers remained stable (-0.5 to 1.5 m/year), while lake-associated glaciers experienced significant velocity surges, peaking at 19.4 m/year in 2021–2022 due to hydrological influences. Debris-covered glaciers recorded the highest mean velocity (0.66 m/year), whereas rock glaciers were the most stable (-0.08 m/year). High-velocity glaciers clustered near the Teesta basin, suggesting localized drivers like increased precipitation and glacial lake expansion. This study provides crucial insights into Himalayan glacier dynamics, informing hydrological modeling, disaster risk assessment, and water resource management. Future research should incorporate climate datasets and advanced modeling to predict glacier responses under varying climate scenarios, ensuring effective cryospheric monitoring amid rapid environmental change.
How to cite: Dutta, S., Ranjan, R. K., and Gaddam, V. K.: Deciphering Glacier Velocity Dynamics in North Sikkim, India (1990–2022) through Geospatial Investigation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20954, https://doi.org/10.5194/egusphere-egu25-20954, 2025.
