Interdisciplinary approaches are needed to reconstruct the behaviour of glaciers beyond the beginning of systematic, direct measurements. Particularly for the period of the Little Ice Age (LIA), historical documents have been very valuable to successfully reconstruct former glacier extents at different sites. An analysis of historical documents on the well-documented Mont Blanc region, for example, provides unique insights into the LIA glacier development.

The Mont Blanc area became popular with artists, scientists, and travellers in the mid-18th century, including Jean-Antoine Linck from Geneva, who is probably the artist to whom we owe the greatest number of unique glacier views. Jean-Antoine Linck was particularly interested in the icy regions, which he discovered and drew with alpinistic daring and naturalistic accuracy, preferably in gouache, although many pencil sketches have also been preserved. From a glacier history perspective, Linck's work is indispensable, even if many of his artworks are not precisely dated by the author: It represents the whole development of the Mont Blanc glaciers, specifically the Mer de Glace and Glacier des Bossons, but also other glaciers during the period from the end of the 18th century until the 19th century glacier maximum around 1820. As an amazing novelty, Linck was probably the first observer to show a glacier advance with the help of two realistic and accurate views from the same position; one as the Glacier des Bossons retreats and the other as it advances. In addition, various views by Linck make it possible to quantify smaller glacier extents, e.g. around 1800 at the Glacier des Bois (Mer de Glace), which were depicted much more rarely.

To distribute his work, Linck subtly used the etching technique to create easily reproducible plates in large format, which are then hand-coloured with gouache and watercolour. This technique allowed him to create numerous reproductions of the same view, while still giving them a unique and original aspect, views that are remarkable for their serenity and silence, while offering luminous atmospheres. These illustrations introduced the realistic representation of the high mountains into the iconography of Genevese painting and thus led to a new kind of landscape painting with a permanent character.

In terms of glacier history, the work of Jean-Antoine Linck has the same significance for the Mont Blanc area as that of Caspar Wolf and Samuel Birmann for the central Swiss Alps or that of Thomas Ender for the Austrian Alps in terms of glacier iconography. Linck was therefore both an artist and a glacier historian.

How to cite: Nussbaumer, S. U. and Zumbühl, H. J.: The glacier views of Jean-Antoine Linck - a milestone for the Mont Blanc glacier history from the 18th to the 19th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5311, https://doi.org/10.5194/egusphere-egu24-5311, 2024.

Glaciers are excellent climate indicators, and the worldwide glacier retreat serves as a warning signal for the current climate change with its dramatic effects on humans and the environment. Visualizing glacier change by means of images can reach a broad public. Historical glacier images, especially from the so-called Little Ice Age (LIA, approx. AD 1300 to 1850 in the European Alps), show the earlier glacier fluctuations in a particularly impressive way and give us a unique insight into the climatic events of that time. These findings are in turn the key to understand current and possible future climate changes.

The long-term research project "Euro-Climhist" is one of the first projects of its kind worldwide to extract historical documentary data on climate and weather from a wide variety of source types, evaluate the data accordingly, and make it generally accessible in an online database (https://www.euroclimhist.unibe.ch). Until now, the Euro-Climhist database consisted mainly of written sources and measurement data. Within this project, the Euro-Climhist database was conceptually extended to include and secure glacier images in the long term, and to make them accessible to researchers and to the public. Around 500 glacier images were specially prepared for the database and provided with the corresponding metadata, i.e., the name of the artist, the original descriptions as well as supplementary descriptions from the literature, the dating of the images, and the image type. In particular, the assignment to one of five image types - drawing, oil painting, print, photograph, or map - allows conclusions to be drawn about the accuracy of the glacier extents depicted.

Besides written evidence, historical pictorial representations of glaciers allow us to reconstruct glacier extents in the Alps from the early 17^th century onwards. Satisfactory quantities of historical material are only available for those glaciers that achieved the necessary degree of fame early on to attract travellers, scientists, and artists. Pictorial representations in painting and graphic arts date back to the early 17^th century, but only appear in large numbers with the emerging popularity of Alpine travel during the 18^th century. Photographs are available from the end of the 1840s.

How to cite: Rohr, C., Nussbaumer, S. U., Walker, C., Haller, C., Widmer, T. T., Fries, M., Würsch, L., and Zumbühl, H.: Integration of historical glacier images into the Euro-Climhist database, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12440, https://doi.org/10.5194/egusphere-egu24-12440, 2024.

The assimilation of early instrumental, documentary, and proxy data into model simulations allows the study of multivariate climate variability from monthly to centennial time scales. The strength of our paleo-reanalysis ModE-RA (Modern Era Reanalysis) lies specifically in the period of the Little Ice Age because the number of assimilated values per year increases from hundreds in the 17^th century to thousands in the 18^th century to tens of thousands in the 19^th century. In addition, recent efforts of weather reconstruction based on early instrumental data even allow for European reconstructions at daily time scales back into the 18^th century.

Here, we present a case study of the global climate and European weather anomalies following the Laki eruption in 1783. Most reports have been limited to the European domain and described an unexpectedly warm summer of 1783 and extremely cold winters in the three following years. Our weather reconstruction and ModE-RA support recent model simulations which suggested atmospheric blocking to be the cause of the unexpected warm anomalies in Europe. However, the entire summer of 1783 was not hot, but only a relatively short period in June and July. On the northern hemisphere scale, we find an aerosol-induced cooling. African and Indian Monsoon rainfall is reduced due to a weaker land-sea temperature gradient in line with the response to strong tropical eruptions and an interhemispheric temperature contrast in line with the response to strong extratropical eruptions. In contrast to recent simulations of the Laki eruption, ModE-RA shows a clear boreal winter warming at high latitudes, slightly dampening the hemispheric-scale cooling signal. In the future, monthly paleo-reanalysis or even daily weather reconstructions could be used to drive models of Little Ice Age glacier dynamics.

How to cite: Franke, J., Friedman, A., Imfeld, N., and Brönnimann, S.: The Laki Eruption – studying Weather and Climate during the Little Ice Age with Paleo-Reanalysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10439, https://doi.org/10.5194/egusphere-egu24-10439, 2024.

Glaciers play a fundamental role in the Earth’s water cycles. They are one of the most important freshwater resources for societies and ecosystems and the recent increase in ice melt contributes directly to the rise of ocean levels. For this reasons, they have been declared as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). Within the Copernicus Climate Change Services (C3S), the global gridded annual glacier mass change dataset provides information on changing glacier resources for the last five decades by combining the glacier outlines from the globally complete Randolph Glacier Inventory with the mass balance and elevation change observations from the Fluctuation of Glaciers database of the World Glacier Monitoring Service (WGMS).

The glacier change product provides a global assessment of annual glacier mass change and related uncertainties (in m w.e. and Gt) and gridded area changes (km²)  since the hydrological year 1975/76 to present, provided in a 0.5°x0.5° (latitude-longitude) global regular grid and in netcdf file format. The new product bridges the gap on spatio-temporal coverage of glacier change observations, providing for the first time in the CDS an annually resolved glacier mass change product using the glacier elevation change sample as calibration. This goal has become feasible at the global scale only recently and thanks to a new globally near-complete (96% of the world’s glaciers) dataset of glacier elevation changes between 2000 and 2020.

The global gridded annual glacier mass change product integrates nicely into the family of the gridded ECV products provided by the C3S CDS. It provides new insights into regional to global glacier mass changes and, hence, has a great potential for contributing to the various state of the climate reports as well as to assessments of the global sea-level budget, the global energy cycle or the global water cycle. Continuation and expansion of the glaciological in-situ observation network is essential for providing the temporal variability of the glacier mass change product. Ensuring the continuation of open source spaceborne datasets with extensive acquisitions tasking planned over glaciated regions is crucial for ensuring the good quality of future glacier products, and one of the greatest gaps in the quality and continuation of the glacier services delivered to C3S.

How to cite: Dussaillant, I., Bannwart, J., Paul, F., and Zemp, M.: Glacier mass change gridded data from 1976 to present derived from the Fluctuations of Glaciers Database - A new product in the Copernicus Service Climate Data Store, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13856, https://doi.org/10.5194/egusphere-egu24-13856, 2024.

Glacier surges are prevalent in the Karakoram and often threaten local residents by submerging land and initiating secondary disasters. The Kyagar Glacier is well known for its surge history as it frequently blocked the downstream valley, leading to a series of high-magnitude glacial lake outburst floods. Although the surge dynamics of the Kyagar Glacier have been broadly described in the literature, there remains an extensive archive of remote sensing observations that have great potential for revealing specific surge characteristics and their relationship with historic lake outburst floods. We propose a new perspective on quantifying the surging process using successive digital elevation models (DEMs), which could be applied to other sites where glacier surges are known to occur. Advanced Spaceborne Thermal Emission and Reflection Radiometer DEMs, High Mountain Asia 8-meter DEMs, and the Shuttle Radar Topography Mission DEM were used to characterize surface elevation changes throughout the period from 2000 to 2021.We also used Landsat time series imagery to quantify glacier surface velocities and associated lake changes over the course of two surge events between 1989 and 2021. Using these datasets, we reconstruct the surging process of the Kyagar Glacier in unprecedented detail and find a clear signal of surface uplift over the lower glacier tongue, along with uniformly increasing velocities, associated with the period of surge initiation. Seasonal variations in surface flow are still evident throughout the surge phase, indicating the presence of water at the glacier bed. Surge activity of the Kyagar Glacier is strongly related to the development and drainage of the terminal ice-dammed lake, which is controlled by the drainage system beneath the glacier terminus.

How to cite: Lv, M.: Quantifying the surging process of the Kyagar Glacier in the Karakoram using successive digital elevation models and optical satellite images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2778, https://doi.org/10.5194/egusphere-egu24-2778, 2024.

Direct glaciological measurements are an important dataset of glacier mass balances but remain concentrated on a small number of glaciers. On hydrological years 2019/20 and 2020/21, 318 annual mass-balance observations were compiled based on 169 glaciers worldwide (Zemp et al., 2023). On the other hand, the current climate crisis now requires a description of cryosphere evolution at a larger scale by quantifying annual snow and ice losses on a larger number of glaciers.

A relevant attempt to fill this gap has been provided by Huggonet et al. (2021) where a global dataset of mass balances at a glacier scale have been generated from 2000 to 2020. While being an extremely valuable glacier mass balance dataset, it is limited to provide mass balance estimation with a time scale longer than 5 years, i.e. annual mass balances cannot be considered reliable.

On the other side, the equilibrium line altitude (ELA) method (Rabatel et al., 2016) have been proven to be an effective approach to reconstruct annual glacier mass balance time series as soon as annual estimation of ELA from satellite multispectral images (e.g. Landsat, Sentinel-2) and at least two digital terrain models (DTMs) acquired at different years are available. Typically, highly accurate DTMs (e.g. airborne LiDAR or photogrammetric DTMs), which are only available on a regional scale base, have been employed within the ELA method.

The main objective of this work is to test the ELA method using as input: 1) Landsat and Sentinel-2 estimation of ELA and 2) ASTER DTMs (Hugonnet et al., 2021). In this way, annual mass balances can be retrieved using satellite data only.

We initially tested this approach over the glaciers in Trentino and South Tyrol where seven glaciers have been monitored through glaciological measurements and different airborne DTMs have been acquired during the last 20 years. Our results show that the use of the ELA method with high resolution airborne DTMs can produce mass balance estimations characterized by an error around 0.3 m w.e. with respect to ground measurements. This error value is in line with estimations conducted with the same method in other regions (e.g. Rabatel et al., 2016) and it is in the error range of ground based measurements. The use of ASTER-based 5 years DTM differences as input of the ELA method can produce estimations with a similar error range. Therefore, the combination of ASTER DTM and ELA extracted from Landsat or Sentinel-2 images may be an interesting approach to produce accurate annual mass balance estimations for many glaciers in the world.

References :

Hugonnet, R. et al. (2021). Accelerated global glacier mass loss in the early twenty-first century. Nature 592, 726–731

Rabatel, A. et al. (2016). Spatio-temporal changes in glacier-wide mass balance quantified by optical remote sensing on 30 glaciers in the French Alps for the period 1983–2014. Journal of Glaciology, 62(236), 1153-1166.

Zemp, M. et al. (2023). Global Glacier Change Bulletin No. 5 (2020-2021). WGMS.

How to cite: Casarotto, C. and Callegari, M.: Annual glacier mass balance estimation through ASTER DTMs and snowlines extracted from Landsat and Sentinel-2 images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9745, https://doi.org/10.5194/egusphere-egu24-9745, 2024.

Understanding the role and dynamics of debris covering alpine glaciers is complex and multi-faceted. A thin or non-continuous layer (smaller than 2cm) promotes melting, whereas a thicker layer insulates the underlying ice. The response of debris-covered glaciers to climate change is not uniform worldwide. These glaciers not only react to the changing climate, but they are also sensitive to debris-cover evolution. To date, studies analysed limited spatio-temporal data and thus do not describe multi-temporal changes in debris cover thickness. However, these strongly impact long-term glacier evolution as topography changes can lead to ice cliff formation, which is known to considerably speed up glacier melt. Multi-temporal high-resolution remote sensing offers the possibility to fill this gap and monitor changes at a small scale. In this contribution, we apply multi-temporal close-range remote sensing to a debris-covered glacier in the Swiss Alps (Zmuttgletscher, Valais, CH). We make use of Unmanned Aerial Vehicle (UAV) surveys equipped with a dual optical-thermal camera together with manual debris excavations and in-situ meteorological data in different years (2020 and 2023). The thermal surveys are calibrated using supraglacial and proglacial lake water temperatures, combined with debris surface temperature measurements. We explore the debris thickness, morphology, and topography evolution of a portion of the glacier, and discuss it in relation to glacier dynamics and debris transport. The work contributes to the understanding of glacier debris evolution, which is often neglected in debris-covered glacier models and global projections.

How to cite: Bramati, G., Hardmeier, F., Adams, J. S., Vieli, A., and Naegeli, K.: Tapping the potential of multi-temporal thermal infrared UAV over a debris-covered glacier , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9700, https://doi.org/10.5194/egusphere-egu24-9700, 2024.

Ice cliffs are known to enhance ablation on debris-covered glaciers and surface ablation. The upstream part of debris-covered glacier tongues is often characterised by downstream-widening supraglacial valleys with hummocky topography, arch-shaped ice cliffs alongside incised and meandering supraglacial channels. The incision of supraglacial channels has been suggested as a potentially important process for the formation of ice cliffs; however, the interactions between channel undercutting and ice-cliff formation are poorly understood and remain to be quantified. In particular, the stream undercutting cannot be observed from nadir-based satellite or UAV methods.

In this study, we therefore use a more local approach to investigate these interactions by applying high-resolution terrestrial remote-sensing methods at the example of two debris-covered glaciers: Satopanth Glacier, located in the Indian Himalayas, and Zmutt Glacier in the European Alps. We combined (i) high-density point cloud data from a terrestrial laser scanner, (ii) drone imagery, (iii) time-lapse imagery, and in situ stake measurements of the channel overhangs and the debris and ice-cliff surfaces at daily and fortnightly intervals during the melting season. By differencing the point clouds and DEMs using a Lagragian reference system, we are able to calculate channel incision and melt rates alongside ice-cliff backwasting rates. We further constrain the evolution of these surfaces with the stake measurements and continuous time-lapse imagery of 30 (Zmutt) and 5 (Satopanth) minute intervals.

Our results show that our approach, particularly the acquisition of point cloud data using terrestrial laser-scanning, offers promising perspectives for analysing channel incision and related ice-cliff backwasting. The dominating processes observed for the evolution of the surface morphology are the backwasting of the exposed ice cliff, the erosion of the stream in the undercut below, and the ablation of the debris-covered surface, which are exposed to a range of external factors (e.g., meltwater flow, air temperature, solar radiation, deposition, and debris thickness). We find that the sideway component of the channel incision usually exceeds the downward component and creates, depending on the size of the stream, undercuts of several 10s of cm (Zmutt) to several meters (Satopanth) in width. The related horizontal undercutting rates are generally comparable or more significant than ice-cliff backwasting and sub-debris ablation. However, we note that the incision and ice cliff morphology varies according to their location and orientation along the meandering meltwater stream. For deeply undercut ice overhangs, we are able to detect downward deformation that occasionally leads to a collapse of the ice cliff above and may thereby indirectly further enhance ice cliff backwasting. 

Our results imply that stream incision is the driving process of undercutting and maintaining the ice cliffs, hence a crucial process for their formation and evolution. The integrated use of high-resolution field-based remote-sensing methods thereby contributed successfully towards a better understanding of the morphological evolution of surfaces with relatively thin debris and the related characteristic supraglacial valleys.

How to cite: Ouvry, B., Walker, C., Kneib, M., Reinthaler, J., Pellicciotti, F., and Vieli, A.: Quantifying the morphological evolution and interaction of ice cliffs and supraglacial stream incision on debris-covered glaciers using high-resolution terrestrial lidar and UAV methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8967, https://doi.org/10.5194/egusphere-egu24-8967, 2024.

Climate change has had a significant impact on the behaviour of the high mountain cryosphere, with widespread glacier retreat and mass loss now occurring in most of the planet’s glacierised mountain ranges over multi-decadal timescales. If we are to accurately understand the impacts of deglaciation on freshwater availability to communities downstream, robust modelling of future glacier meltwater yield is paramount. Meteorological observations at glacierised elevations are essential to drive simulations of the energy balance at glacier surfaces, and therefore glacier melt, although such records are sparse in most high mountain regions due to the logistical challenges associated with making even short-term measurements. The scarcity of high-altitude meteorological observations has resulted in only limited understanding of factors such as the spatial and temporal variability of temperature lapse rates, precipitation amounts and phase, and the prevalence of conditions suited to sublimation, all of which have an important influence on glacier mass loss rates at high elevation.

Here we summarise the installation of meteorological and glacier ablation stations in different climatic zones of the South American Andes - the Tropical Andes of Peru (Nevado Ausangate basecamp, 4800 m, (13°48'45.96"S, 71°12'53.18"W) and Bolivia (Laguna Glaciar, 5300 m, 15°50'10.59"S, 68°33'11.30"W), the Subtropical Andes (Glaciar Universidad, Chile, 2540 m, 34°43'10.07"S, 70°20'44.98"W) and Patagonian Andes (Lago Tranquillo, Chile, 280 m, 46°35'47.00"S, 72°47'38.91"W) – as part of the NERC-funded Deplete and Retreat Project. Meteorological station records include time series of air temperature and pressure, relative humidity, wind speed and direction, incoming and outgoing short- and longwave radiation, precipitation amount and phase. Coincident glacier ablation is monitored at each site using ‘Smart Stakes’, recording surface elevation change on-glacier. We describe station situation, installation and preliminary measurements, along with aims and objectives of analyses using the meteorological time series.

How to cite: King, O., Matthews, T., Andrade, M., Garcia, J.-L., Bravo, C., Buytaert, W., Calle, J. M., Dussaillant, A., Edwards, T., Irarrazaval, I., Perry, B., Potter, E., Ticona, L., Davies, B., and Ely, J.: Establishing glacier proximal meteorological and glacier ablation stations in different climatic zones along the South American Andes., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15640, https://doi.org/10.5194/egusphere-egu24-15640, 2024.

High Mountain Asia (HMA) contains the largest glacier inventory outside the polar regions and the melting of these glaciers provides an important freshwater supply for over 250 million people in south, central, and east Asia. Recent studies have quantified glacier changes over the past decades in this area mainly based on the interpretation of satellite imagery, while few studies have investigated the longer-term (centennial-scale) glacier changes due to the lack of mapped outlines and reliable methods to reconstruct the three-dimensional surfaces and volumes of past glaciers. We compiled a dataset of >15,000 mapped glacier outlines during the Little Ice Age (LIA) in the Himalayas, Gangdise, Tanggula, and Tian Shan and reconstructed the ice thickness and volumes of LIA glaciers and their corresponding contemporary glaciers based on a flowline-based GIS model, PalaeoIce. Initial results of 640 LIA glaciers and their corresponding 1466 contemporary glaciers from Tian Shan indicate a total of 47.6% loss of ice volumes since the LIA and the ice volume loss are negatively correlated with glacier area and equilibrium line altitude. This presentation reports the reconstruction of >15,000 LIA glaciers and their corresponding >20,000 contemporary glaciers in the four mountain ranges (Himalayas, Gangdise, Tanggula, and Tian Shan) to examine the spatial pattern of LIA glacier changes and their influencing factors (climate, topography, and debris cover). This work provides important insights into the impacts of glacier changes on water resources in High Mountain Asia in the past 300-500 years.

How to cite: Li, Y.: Patterns and influencing factors of glacier changes in High Mountain Asia since the Little Ice Age, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6015, https://doi.org/10.5194/egusphere-egu24-6015, 2024.

Glacier dynamics and the effects of climate change accelerate bedrock erosion and instability of the surrounding topography, causing clean glaciers to be gradually covered by debris, particularly in the ablation zones. While the area of glaciers covered worldwide is increasing, there are few studies on this phenomenon in tropical glaciers and its possible significant effects on glacier melt. In this context, this study analyzes the spatio-temporal evolution of the area of glaciers covered by debris in the Cordillera Blanca from 1962 to 2020. 

To achieve this aim, we used data from the Peruvian National Glacier Inventory for 1962 and 2020. We also identify the covered glaciers through the photo-interpretation of geomorphological features, such as the color and texture of the ground surface, the presence of thermokarst zones, and the formation of small lakes/lagoons observed in the satellite images. In addition, we got the topographic features from the ALOS PALSAR digital elevation model.

The outcomes of this investigation reveal an increase in the number and surface area of glaciers covered, from 33 units (15.41 km2) in 1962 to 173 units (23.06 km2) in 2020. This shows an increase of 49.64% from the glacier area covered by debris. The increase in covered glaciers in the Cordillera Blanca could be because many glaciers identified as debris-free in 1962 were partially or totally covered in 2020; 17.13 km2 of the glacier debris-free area was covered by debris during this period. It has been observed that 93% of the area covered by debris is on slopes greater than 8°. Of these, 25% were in the 24° - 33° range, and 23% were on steeper slopes than 33°. The orientation analysis indicates a predominance of surface covered towards the southwest and south.

Likewise, the areas of glacier retreat covered between 1962 and 2020 were analyzed, identifying 9.45 km2 of glacier surface loss. 18% of the loss areas are on slopes steeper than 8º, mainly from 8º to 17º slope, where 28% of the loss area is located. Meanwhile, a clear retreat trend is observed in those areas with a north orientation of 95% and a northeast orientation of 5%.

These findings suggest a possible association between the higher magnitude slope conditions and the formation of covered glaciers, while the orientation influences the retreat of these glaciers.

How to cite: Curo, Y., Fernandez, J. D. D., Celmi, G., Robles, D., and Mejia, M.: Evolution of the covered glaciers in the Cordillera Blanca during the period 1962 - 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14469, https://doi.org/10.5194/egusphere-egu24-14469, 2024.