The global cryosphere with all its components is strongly impacted by climate change and has been undergoing significant changes over the past decades. Glaciers are shrinking and thinning. Snow cover and duration is reduced, and permafrost, in both Arctic and mountain environments, is thawing. Changes in sea ice cover and characteristics have attracted widespread attention, and changes in ice sheets are monitored with care and concern. Risks associated with one or several of these cryosphere components have been present throughout history. However, with ongoing climate change, we expect changes in the magnitude and frequency of hazards with profound implications for risks, especially when these interact with other aspects relating to context vulnerability, exposure, and other processes of biophysical and/or socioeconomic drivers of change. New or growing glacier lakes pose a threat to downstream communities through the potential for sudden drainage. Thawing permafrost can destabilize mountain slopes, and eventually result in large landslide or destructive rock and ice avalanches. An accelerated rate of permafrost degradation in low-land areas poses risk to existing and planned infrastructure and raises concerns about large-scale emission of greenhouse gases currently trapped in Arctic permafrost. Decreased summertime sea ice extent may produce both risks and opportunities in terms of large-scale climate feedbacks and alterations, coastal vulnerability, and new access to transport routes and natural resources. Furthermore, rapid acceleration of outlet glacier ice discharge and collapse of ice sheets is of major concern for sea level change. This session invites contributions across all cryosphere components that address risks associated with observed or projected physical processes. Contributions considering more than one cryosphere component (e.g. glaciers and permafrost) are particularly encouraged, as well as contributions on cascading processes and interconnected risks. Contributions can consider hazards and risks related to changes in the past, present or future. Furthermore, Contributions may consider one or several components of risks (i.e. natural hazards, exposure, vulnerability) as long as conceptual clarity is ensured. Furthermore, cases that explore diverse experiences with inter- and transdisciplinary research, that sought to address these risks with communities through adaptation and resilience building, are also be considered.
vPICO presentations: Fri, 30 Apr
Marine plastic pollution is a growing worldwide environmental concern as recent reports indicate that increasing quantities of litter disperse into secluded environments, including Polar Regions. Plastic degrades into smaller fragments under the influence of sunlight, temperature changes, mechanic abrasion and wave action resulting in small particles < 5mm called microplastics (MP). Sea ice cores, collected in the Arctic Ocean have so far revealed extremely high concentrations of very small microplastic particles, which might be transferred in the ecosystem with so far unknown consequences for the ice dependant marine food chain. Sea ice has long been recognised as a transport vehicle for any contaminates entering the Arctic Ocean from various long range and local sources. The Fram Strait is hereby both, a major inflow gateway of warm Atlantic water, with any anthropogenic imprints and the major outflow region of sea ice originating from the Siberian shelves and carried via the Transpolar Drift. The studied sea ice revealed a unique footprint of microplastic pollution, which were related to different water masses and indicating different source regions. Climate change in the Arctic include loss of sea ice, therefore, large fractions of the embedded plastic particles might be released and have an impact on living systems. By combining modeling of sea ice origin and growth, MP particle trajectories in the water column as well as MPs long-range transport via particle tracking and transport models we get first insights about the sources and pathways of MP in the Arctic Ocean and beyond and how this might affect the Arctic ecosystem.
How to cite: Peeken, I., Bergami, E., Corsi, I., Hufnagl, B., Katlein, C., Krumpen, T., Löder, M., Wang, Q., and Wekerle, C.: The role of sea ice for plastic pollution in the Arctic, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13366, https://doi.org/10.5194/egusphere-egu21-13366, 2021.
As the Arctic ice cover has transitioned to a younger and thinner state it has become weaker and therefore increasingly mobile. One of the key indicators of this change is the increase in ice flux through Nares Strait, which connects the central Arctic to Baffin Bay and is an export pathway for some of the oldest and thickest sea ice remaining within the Arctic. Historically ice flux through the narrow Strait was seasonally limited by the formation of an ice arch, however as the ice cover has thinned the arch no longer forms every winter, and when it does form it tends to break up earlier. An increase in ice flux through Nares Strait not only affects the retention of old thick ice within the central Arctic, but also affects the icescape downstream of the Strait that extends from Baffin Bay, through the Labrador Sea and towards the southern ice edge around Newfoundland. While an ice cover does form annually around Newfoundland, it is typically a thin seasonal ice cover, which forms in January and is gone by May. However, during spring 2017 the ice conditions were considerably heavier, presenting hazardous conditions for the local maritime industry into June and requiring the Canadian Coast Guard research ice breaker Amundsen be pulled off of its scientific cruise and used to escort vessels and conduct search and rescue operations along Newfoundland’s northeast coast. The ice cover was considerably thicker and more extensive than previous years and sank two fishing vessels that became beset within the ice pack. Using a unique suite of in situ observations we confirmed that multiyear sea ice from the central Arctic was present within this anomalous ice cover. Using satellite imagery and regional ice charts we tracked the source of this multiyear ice back to Nares Strait and the central Arctic. While regional in focus, this work highlights how the decline of the Arctic ice pack has implications for downstream areas where risk may be increasing as the ice pack declines.
How to cite: Babb, D., Barber, D., Ehn, J., Chan, W., Mathes, L., Dalman, L., Campbell, Y., Harasyn, M., Lukovich, J., Zagon, T., Papakyriakou, T., Capelle, D., and Gariepy, A.: Increasing Mobility of High Arctic Sea Ice Increases Marine Hazards off the East Coast of Newfoundland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12793, https://doi.org/10.5194/egusphere-egu21-12793, 2021.
Due to their large mass, ice sheets induce significant stresses in the Earth’s crust. Stress release during deglaciation can trigger large-magnitude earthquakes, as indicated by surface faults in northern Europe. Thus, the current ice-mass loss in Greenland can be accompanied by earthquakes. Here, we will present an example of a possible large magnitude earthquake that occurred during the large melting period of the Greenland Ice Sheet in the early Holocene. The glacially induced stresses showed an instability occurring at 10,600 years ago. An offset in past sea level indicators falls within the same time frame, which gave us indications that the stresses have been released by an earthquake. The potential fault could have slipped up to 47 m, resulting in a large magnitude earthquake, if only one event occurred. The earthquake may have shifted relative sea level observations by several meters. In addition, as the potential fault is located offshore, the earthquake could have produced a tsunami in the North Atlantic Ocean with runup heights of up to 7.2 m in the British Isles and up to 7.8 m along Canadian coasts. Thus, ice-mass loss is strongly linked to the occurrence of earthquakes and even earthquakes-related tsunami. These scenarios due to a changing cryosphere can have effects for all countries bordering the North Atlantic Ocean and are in addition to the well-known sea-level rise.
How to cite: Steffen, R., Steffen, H., Weiss, R., Lecavalier, B., Milne, G., Woodroffe, S., and Bennike, O.: Earthquakes induced by ice-mass loss: A case example for southern Greenland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-335, https://doi.org/10.5194/egusphere-egu21-335, 2021.
When rain falls on an existing cover of snow, followed by low temperatures, or falls as freezing rain, it can leave a hard crust. These Arctic rain on snow (ROS) events can profoundly influence the physical environment, animals, and human livelihoods. Impacts can be immediate (e.g., on human travel, herding, or harvesting) or evolve or accumulate, leading, for example, to massive starvation-induced die offs of reindeer, caribou and musk oxen. The international Arctic Rain on Snow Study (AROSS) will detect and catalogue ROS events, and study their impacts, addressing human-environment relationships, associated meteorological conditions, and challenges in their detection. We offer a path forward to anticipate and mitigate impacts through knowledge co-production. Although ROS events can be detected, and their intensity and trends across the Arctic region evaluated by combining data from satellite remote sensing, atmospheric reanalyses and meteorological station records, information most germane to impacts, such as the thickness of ice layers, how ice layers form within a snowpack, and antecedent conditions that can amplify impacts, can only be obtained through collaboration with local and Indigenous knowledge-holders.
How to cite: Barrett, A. and Serreze, M.: The Arctic Rain on Snow Study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13980, https://doi.org/10.5194/egusphere-egu21-13980, 2021.
Isfallsglaciären in Northern Sweden is a steep polythermal valley glacier located in the Kebnekaise Mountains, which is well studied and thoroughly observed because its proximity to Tarfala Research Station run by Stockholm University. Isfallsglaciären is also included in the Swedish monitoring program for glaciers reported to WGMS.
The glacier advanced during the 1990s, but continues to recede and thin at a high rate since the turn of the century. On August 26, 2018, a 5x 105 m3 large portion of Isfallsglaciärens ice tongue decoupled from the main glacier and began to slide down-valley. Within 5 days, a 50 m wide gap had formed which increased to a width of c. 80 m later during the autumn. The front of the decoupled ice section advanced 50 m (timeframe?) over moderately inclined bed topography, and came eventually to a halt, without developing into an ice avalanche. The upstream cliff of the main glacier advanced first at a high rate and then progressively slowed down forming a new glacier front. [NK1]
The event is very well documented by recurrent aerial photography taken during 2016-2020, as well as more frequent inage acquisition a few weeks before, and shortly after, the event. The photos have been analyzed using structure-from-motion photogrammetry to reveal the magnitude of change at a decimeter-level.
Departing from a description of this event, we discuss the impact of hazardous changes on glaciers becoming steeper and thinner due to recession, as well as complications arising for glacier front monitoring as part of the WGMS program.
Similar events have been reported at glaciers elsewhere in Sweden but these events are less well documented and do not influence the monitoring program. In this paper we will describe how data have been handled and inspire to similar studies in any glacier area. We will also discuss the issue in a glacier monitoring perspective.
How to cite: Holmlund, P., Kirchner, N., and Mannerfelt, E.: Hazardous calving event on Isfallsglaciären in Northern Sweden as a result of climate warming, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1761, https://doi.org/10.5194/egusphere-egu21-1761, 2021.
Jökulhlaups from marginal and subglacial lakes are a considerable hazard in Iceland and the rapid retreat of glaciers and ice caps is leading to hydrological changes in many locations at or near the glaciers. This calls for careful monitoring of glaciers and proglacial areas.
On August 17 2020, increased discharge was observed in Hvítá, a glacial river originating in the ice cap Langjökull. Sediment-laden jökulhlaup waters filled a narrow gorge of the river near the farm and tourist resort Húsafell and dead salmon were found strewn over fields 30–40 km downstream.
Reconnaissance trips, overflights and satellite image studies revealed the following course of events:
A marginal glacial lake (current size: 1.3 km2) started forming at 890 m elevation at the western margin of Langjökull after the turn of the century. Sentinel-2 satellite images indicate that subglacial outflow from the lake had started in the morning of August 17. The exact path of the 2 km long subglacial water course can be inferred from a Landsat-8 image taken on November 11 2020. The image shows a narrow surface depression resulting from lowering of the glacier surface when the subglacial tunnel carrying the water was formed. The ice thickness averages 70 m along the flowpath.
Emerging from beneath the ice cap, the water flowed 13 km through the Svartá river canyon, eroding sediment from the river bed and canyon walls. Fresh colouring and sediment deposition was observed on sandur plains where Svartá joins the Geitá and Hvítá rivers.
Observations of the jökulhlaup (water level and flow velocity) as it passed beneath a bridge near Húsafell help constrain discharge levels and flood volume at a location 18 km from the outlet at Langjökull. In addition, real-time data on Hvítá river water level are available from the Kljáfoss hydrometric station 35 km further downstream, discharge started rising from a background value of 90 m3/s on August 17 at 16:00. The flood peaked there at 260 m3/s at 01:45 in the early morning of August 18 and had subsided again at noon on that day.
Using imagery from the Sentinel-2 satellites the area of the marginal lake is estimated to have diminished from 1.29 km2 to 0.46 km2 during the jökulhlaup. A lowering of 4 m has been determined from aerial imagery and the total volume released was 3.4 million m3 according to preliminary estimates. We estimate an average flow velocity of 3±1 m/s for the entire distance from the outlet at the glacier to Kljáfoss.
The glacier margin in the region has retreated by 500-1000 m and thinned by 3 m/a in the period 2004-2019 leading to the formation of the proglacial lake. Flooding events occurring in 2014 and 2017 have now been detected in hydrometric and remote sensing data. The lake is likely to become larger when retreat continues and further thinning of the ice may lead to more frequent jökulhlaups in coming years. Plans to monitor the lake level and install early warning systems will be outlined in the presentation.
How to cite: Thorsteinsson, T., Eythórsdóttir, K. G., Jensen, E. H., Jónsdóttir, I., Pálsson, F., Gunnarsson, A., Pálsson, H. Sk., Sigurðsson, O., Karlsdóttir, G. H., Þrastarson, R. H., Sigurðsson, G., Jóhannesson, T., and Roberts, M. J.: The August 2020 jökulhlaup from a marginal lake at Langjökull, W-Iceland: Course of events, discharge and volume estimates, future monitoring, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13666, https://doi.org/10.5194/egusphere-egu21-13666, 2021.
Topographic development via paraglacial slope failure (PSF) represents a complex interplay between geological structure, climate, and glacial denudation. Where debris generated by PSFs is deposited on the surface of a glacier, this debris can increase the extent or thickness of a supraglacial debris-cover, in turn modifying glacier ablation and affecting meltwater generation. To date, little attention has been paid to intensity and frequency of PSFs and their significance as a geomorphic agent and hazard in glacierised, monsoon temperate regions of Southeast Tibet. We mapped PSFs along the 5 km-long, west-east trending ice tongue of Hailuogou Glacier (HLG), Mt. Gongga, using repeat satellite- and UAV-derived imagery between 1990 and 2020. Three types of PSF were identified: (A) rock fall, (B) slide and collapse of sediment-mantled slopes, and (C) gulley headwards erosion. We analyzed the formation, evolution and current state of these PSFs and discuss these aspects with relation to glacier dynamics and paraglacial geomorphological history. South-facing slopes (true left of HLG) showed more destabilization and higher PSF activity than north-facing slopes. We observed annual average rates of downslope sliding for type B PSFs of 1.6-2.6 cm d-1, whereas the average upward denudation rate for type C PSFs was 0.7-3.39 cm d-1. We show that type A PSFs are non-ice-contact rock collapses that occur as a long-term paraglacial response following glacier downwasting and the exposure of steep rocky cliffs and which could also be influenced by precipitation, freeze-thaw cycling, earthquakes or other factors. In contrast, type B and C PSFs are a more immediate response to recent glacier downwasting. We further argue that the accelerating downwasting of glacier are used as a preparatory or triggering factor, which could directly or indirectly cause the PSFs.
How to cite: Zhong, Y., Liu, Q., Nie, Y., Westoby, M., Zhang, B., Cai, J., Liao, H., and Liu, G.: Intensified paraglacial slope failures due to accelerating downwasting of a temperate glacier in Mt. Gongga, Southeastern Tibet Plateau, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1086, https://doi.org/10.5194/egusphere-egu21-1086, 2021.
In recent decades, slope instability in high-mountain regions has often been linked to the increase in temperature and the associated permafrost degradation and/or the increase in frequency/intensity of rainstorm events. In this context we analyzed the spatiotemporal evolution and potential controlling mechanisms of small to medium-size rockfalls and debris flows in a small catchment of the Italian Alps (Sulden/Solda basin). We found that rockfall events have been increasing since the 1990s, whereas debris flows have increased only since 2010. The current warming trend of mountain regions such as the Southern Alps is leading to an increased elevation of rockfall detachment areas (altitudinal shift of ca. 300-400 m in the study site), mostly controlled by frost-cracking and permafrost thawing. In contrast, the occurrence of debris flows does not exhibit such an altitudinal shift, as it is primarily driven by extreme precipitation events exceeding the 75th percentile of the intensity-duration rainfall distribution. The possible occurrence of a debris-flow event in this environment may be additionally influenced by the accumulation of unconsolidated debris over time, which is then released during extreme rainfall events. Overall, there is evidence that the upper Sulden basin (above ca. 2500 m asl), and especially the areas in the proximity of glaciers, have experienced a significant decrease in slope stability since the 1990s and that an increase in rockfalls and debris flows during spring and summer can be observed. Our study thus confirms that “forward-looking” hazard mapping should be undertaken in these increasingly frequented areas of the Alps, as these environmental changes have elevated the overall hazard level in these high-elevation regions.
How to cite: Savi, S., Comiti, F., and Strecker, M.: Global warming, slope stability, and the dynamization of geological hazards in high mountain regions: a case study from the Eastern Alps., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2070, https://doi.org/10.5194/egusphere-egu21-2070, 2021.
As everywhere in the Andes, tropical glaciers have been rapidly retreating since several decades. The glaciers of Cotopaxi volcano, Ecuador, have been reduced in area by about 50% since 1976 (Cáceres, 2017). The Cotopaxi is mostly famous for its capacity to produce massive lahars during volcanic eruptions, but comparably smaller, secondary lahars generated in post-eruptive periods by heavy rainfall occur more frequently on the volcano’s flanks. However, since a few years, secondary lahars that originate in proglacial areas without any clear trigger mechanism are recorded at Cotopaxi. This raises the question of whether there exists a process-based link between the occurrence of secondary lahars and the retreat of cold-based glaciers with accompanied permafrost degradation in the former subglacial frozen pyroclastic material over the following years and decades.
Here, we present the data obtained from laboratory-calibrated Electrical Resistivity Tomography (ERT) and Seismic Refraction Tomography (SRT) conducted near the glacier margin between 5000 and 5300 m asl, which provide a better understanding of frozen/unfrozen conditions and the structure of the subsurface. In addition, data loggers have been recording surface air temperatures close to the glacier since May 2018. Our measurements show that permafrost cannot develop under current thermal conditions, but high electrical resistivities at depths of 10-20 m correspond to calibrated rock temperatures below 0 °C. The detected frozen lenses may act as detachment planes of periglacial secondary lahars in pyroclastic material recently exposed by glacier retreat.
Cáceres, B. (2017). Goal workshop 2017 Mexico 135 Evolución de los glaciares del Ecuador durante los últimos 60 años y su relación con el cambio climático. Conference paper: The role of Geosciences to societal development: A German-Latin American Perspective. GOAL Geo-Network of Latin American-German Alumini. P. 149. México: UANL-Monterrey-México.
How to cite: Frimberger, T., Andrade, D., and Krautblatter, M.: Towards a better understanding of the role of glacier retreat and permafrost degradation in triggering secondary lahars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13502, https://doi.org/10.5194/egusphere-egu21-13502, 2021.
Molards are cones of loose debris, from ~ 50 cm to ~ 15 m in height, and are the remnants of formerly ice-cemented blocks that moved within a landslide, then degraded progressively (e.g., ). Thus, presence of molards in landslide deposits implies an involvement of both ice-cemented and non-ice-cemented ground within the mass movement, and so the presence of an area of discontinuous permafrost at the level of the detachment zone. Permafrost is frozen or unfrozen ground that remains < 0°C for at least two consecutive years, and it can be sensitive to temperature variations . Increasing temperatures can cause its degradation, which can create areas of discontinuous permafrost and enhance slope instability (e.g. ), which represents a threat for populations in polar and mountainous regions . Therefore, accurately identifying areas of discontinuous permafrost is a contemporary challenge for assessments of the state and evolution of permafrost, and for understanding landslide-related hazards to protect local populations.
In this context, we will carry out physical modelling of the degradation of initial ice-cemented blocks made of sediments into molards. The M2C laboratory contains two cold rooms – the largest one > 12 m² – that can go down to -20°C, allowing near-field-scale simulations to be performed. We are developing an experimental protocol that consists in freezing mixes of sediment and water in 30 cm cubes, and then observing their degradation under controlled conditions. We identified grain size of the sediment and its ice content as the main two parameters that should influence the degradation process. Therefore, we will vary these parameters in the first series of experiments. We will observe the degradation processes that occur (e.g. grain falls, gravitational collapses, debris flows) using video cameras. The thaw-front propagation will be monitored by thermocouples within the frozen blocks. An array of time-lapse cameras will be used to produce time series of elevation models to monitor the 3D morphological evolution from blocks to molards. Air temperature and humidity will be monitored. Data on grain size, ice content, degradation processes and temperature/humidity will be used to calibrate a numerical model, which will allow us to explore a parameter space inaccessible/impractical for the laboratory (e.g. bigger scales, or realistic diurnal/seasonal thermal cycles). The final 3D shape (e.g. height, slope, basal area covered) of experimental molards should vary according to the initial parameters (i.e. grain size and ice content) and these measurements will inform the criteria used to distinguish molards from other similar landforms, such as hummocks or hummocky moraine, in the field and/or from remote sensing data.
Acknowledgements: authors thank the Agence Nationale de la Recherche for funding the ANR-19-CE01-0010 PERMOLARDS project, which supports this experimental work.
References:  Morino C. et al. (2019) EPSL 516, 136-147.  Hinzman L. D. et al. (2005) Climate Change 72, 251-298.  Dramis F. et al. (1995) PPP 6, 73-82.  Saemundsson Þ. et al. (2003) In: Rickenman, D., Chen, C.I. (Eds.), Debris-Flow Hazards Mitigation: Mechanics, Prediction, and Assessment. 1, pp. 167–178.
How to cite: Philippe, M., J. Conway, S., Font-Ertlen, M., Morino, C., and Bourgeois, O.: Link between molards and permafrost degradation: an experimental study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8268, https://doi.org/10.5194/egusphere-egu21-8268, 2021.
The Grandes Jorasses Massif culminates at 4203m at the Punta Walker summit on the border between France and Italy. The south slope of Grandes Jorasses is widely glaciated and overlies a populated and highly frequented area, the Val Ferret, presenting the main infrastructure being the road in the valley bottom and different hamlets the most important being Planpincieux village. Located at an altitude between 3900 and 4100 m, the Whymper Serac is a hanging glacier that undergoes periodic gravity-driven instabilities. On 1st June of 1998, 150.000m3 of ice fell, and the resulting ice avalanche reached 1750m, at a mere 400m from houses of the Le Pont village and the main Road. The monitoring activity started in 1997: a series of boreholes had been drilled to assess the basal thermal regime of the Serac and subsequently install a monitoring system for failure prediction time. Since then, no other thermal investigation was repeated.
In September 2020, three thermistor chains in three different boreholes were installed by means of hot water diesel-powered drill machine on Whymper Serac. Geophysical and topographic reconstructions at Whymper Serac are crucial for the volume estimation of possible instabilities; therefore, to assess ice thickness changes and morphological modifications, different geophysical soundings and topographical surveys were performed in 2020. The ice thicknesses were estimated employing a first airborne GPR survey on the 4th of July 2020 using a pair of orthogonal 25 MHz antennas; a second airborne GPR survey was performed using a single 40 MHz antenna on 14/12/2020. Moreover, an in-situ measure was performed through passive seismic sounding later processed as HVSR analysis to assess ice thickness estimation.
The geomatic analysis was performed by aero photogrammetric UAV surveys, and additional GCPs were materialized. The first assessment of thermal regime variation on the Serac suggests that risk scenarios, as well as monitoring possibilities, are rapidly evolving. According to these findings, bigger volumes could be involved in the destabilization of the Serac, and the evolution of the Serac from cold-based to polythermal poses a big challenge in the monitoring of deformations for the possibility of time prediction of failures. Therefore, experimentation of a long-range GB-InSAR surface deformations measures has begun to implement the existing monitoring network based on a robotized total station with reflective prisms used on the Serac. The installation of more thermistor chains is planned for summer 2021, to validate the previous results. Ground-based GPR soundings and more HVSR seismic measurements have as well been planned for 2021 for the more robust reconstruction of the bedrock geometry.
How to cite: Troilo, F., Gottardelli, S., Giordan, D., Dematteis, N., Godio, A., and Vincent, C.: Geophysical and geomatic recent surveys at Whymper hanging Glacier (Aosta Valley – Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5178, https://doi.org/10.5194/egusphere-egu21-5178, 2021.
A prominent phenomenon accompanying glacier retreat is the formation of new lakes. Such glacial lakes are the subject of numerous studies and investigations due to their potential to produce far-reaching glacial lake outburst floods (GLOFs), but also because they might provide opportunities for water resource management and energy production. Here we present a first global inventory of potential future glacial lakes, along with expected formation times under different RCP scenarios.
From published datasets of ice thickness distributions of all glaciers of the world, we identified glacier bed overdeepenings and extracted parameters of potential future lakes, such as area, depth and volume. The consideration of the ensemble of ice thicknesses allowed for a first-order quantification of uncertainties. We identified 67,000 (ranging from 55,000 to 87,000) overdeepenings with volumes larger than 1 x 106 m3, the total surface area and volume of corresponding potential lakes is 61,000 (56,000 to 64,000) km2 and 4,600 (3,100 to 7,200) km3, respectively. However, these numbers are based on the assumption of fully water-filled overdeepenings and therefore represent upper bound estimates. Global results are strongly influenced by very large depressions identified beneath (flat) polar glaciers and ice caps. We then combined potential future lake sites with estimated future glacier extents from a global glacier evolution model (GloGEM), in order to estimate formation periods of these future lakes, considering different RCPs. Strong regional differences are also found in the anticipated formation periods: While in the low latitudes most future lakes are expected to form in the current decade, irrespective of the RCP, Arctic regions have highest lake formation rates towards the end of the 21st century, with the majority of bed overdeepening not being exposed by glacier retreat until 2100. In mid latitude mountain regions, large differences between RCP2.6 and RCP8.5 exist in regard of the timing of lake formation and the amount of total uncovered overdeepenings.
In addition to geometric properties and expected formation periods, the topographic potential for impacting mass movements, such as rock or ice avalanches, is determined for each overdeepening. In combination with potential lake volume and watershed area of the lake, these characteristics can be used for a first order estimation of lake outburst susceptibility. With a basic flow routing algorithm, potential outburst trajectories are modeled for each overdeepening. In combination with information on population density, settlements and further socio-economic and environmental datasets, this information can be used for future analyses of hazards, risks and opportunities associated with these potential future glacial lakes.
How to cite: Frey, L., Frey, H., Huss, M., Allen, S., Farinotti, D., Huggel, C., Emmer, A., and Shugar, D.: A global inventory of potential future glacial lakes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4774, https://doi.org/10.5194/egusphere-egu21-4774, 2021.
The deglaciation since the end of the Little Ice Age (LIA, ~1850) has given way to >700km² of “new” landscape in Switzerland. Glacial lakes are a conspicuous feature of this new landscape – with relevance for natural hazards, hydropower and landscape planning. In this study, we compiled an inventory of glacial lakes for Switzerland for the year 2016. Using existing data, we investigated the evolution of glacial lakes in Switzerland for six time periods since the LIA. Additionally, we compiled information constituting a basis for hazard assessment for all ice-contact lakes in 2016 and all lakes >0.5 ha, i.e. surface outflow, dam type and material, and lake freeboard.
We found that a total of 1230 lakes formed over the period of ~170 years, 982 still existing in 2016. The largest lakes are >0.4 km² (40 ha) in size, while the majority (>90%) are smaller than 0.01 km². Annual increase rates in area and number peaked in 1946-1973, decreased towards the end of the 20th century, and reached a new high in the latest period 2006-2016. For a period of 43 years, we compared modelled overdeepenings from previous studies to actual lake genesis. For a better prioritisation of formation probability, we included glacier-morphological criteria such as glacier width and visible crevassing. About 40% of the modelled overdeepened area actually filled with water. The inclusion of morphological aspects clearly aided in linking a lake formation probability to a modelled overdeepening.
Fig. 1: Glacial lake distribution in Switzerland and its evolution over time.
How to cite: Mölg, N., Huggel, C., Herold, T., Storck, F., Allen, S., Haeberli, W., Schaub, Y., and Odermatt, D.: Inventory and genesis of glacial lakes in Switzerland since the Little Ice Age, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12144, https://doi.org/10.5194/egusphere-egu21-12144, 2021.
On 28 November 2020, about 18 Mm3 of quartz diorite detached from a steep rock face at the head of Elliot Creek in the southern Coast Mountains of British Columbia. The rock mass fragmented as it descended 1000 m and flowed across a debris-covered glacier. The rock avalanche was recorded on local and distant seismometers, with long-period amplitudes equivalent to a M 4.9 earthquake. Local seismic stations detected several earthquakes of magnitude <2.4 over the minutes and hours preceding the slide, though no causative relationship is yet suggested. More than half of the rock debris entered a 0.6 km2 lake, where it generated a huge displacement wave that overtopped the moraine at the far end of the lake. Water that left the lake was channelized along Elliot Creek, deeply scouring the valley fill over a distance of 10 km before depositing debris on a 2 km2 fan in the Southgate River valley. Debris temporarily dammed the river, and turbid water continued down the Southgate River to Bute Inlet, where it produced a 70 km turbidity current and altered turbidity and water chemistry in the inlet for weeks. The landslide followed a century of rapid glacier retreat and thinning that exposed a growing lake basin. The outburst flood extended the damage of the landslide far beyond the limit of the landslide, destroying forest and impacting salmon spawning and rearing habitat. We expect more cascading impacts from landslides in the glacierized mountains of British Columbia as glaciers continue to retreat, exposing water bodies below steep slopes while simultaneously removing buttressing support.
How to cite: Geertsema, M., Menounos, B., Shugar, D., Millard, T., Ward, B., Ekstrom, G., Clague, J., Lynett, P., Friele, P., Schaeffer, A., Jackson, J., Higman, B., Dai, C., Brillon, C., Heathfield, D., Bullard, G., Giesbrecht, I., and Hughes, K.: A landslide-generated tsunami and outburst flood at Elliot Creek, coastal British Columbia , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9148, https://doi.org/10.5194/egusphere-egu21-9148, 2021.
On 23rd February 2020, a landslide-triggered GLOF process chain was initiated from the SW slope of Nevado Salkantay, Cordillera Vilcabamba, Peru. An initial slide evolved into a rock/ice avalanche and part of the released material fell into the moraine-dammed Lake Salkantaycocha, triggering a displacement wave which overtopped and eroded the distal face of the dam. Dam overtopping resulted in a far-reaching GLOF causing fatalities and people missing in the valley downstream. In this contribution, we analyse the situation before and after the event as well as the dynamics of the GLOF process chain, based on field investigations, remotely sensed data, meteorological data, and a computer simulation with a two-phase flow model. Comparing pre- and post-event field photographs helped us to estimate the initial landslide volume of 1–2 million m³. Meteorological data suggest rainfall and/or melting/thawing processes as possible causes of the landslide. The simulation reveals that the landslide into the lake created a displacement wave height of up to 27 m. We reconstructed a released volume 57,000 m3 (less than 10% of lake volume) and estimated a total GLOF peak discharge almost 10,000 m³/s at the dam. The lake had 40 m dam freeboard at the time of a GLOF, and the lake level increased by 10–15 m directly after the event, since most of the volume of landslide material deposited in the lake (roughly 1.3 million m³). The model results show a good fit with the observations, including the travel time to the uppermost village. The findings of this study serve as a contribution to the understanding of landslide-triggered GLOFs in changing high-mountain regions.
How to cite: Vilca, O., Mergili, M., Emmer, A., Frey, H., and Huggel, C.: Reconstruction of the sudden drainage of a moraine-dammed lake in the Cordillera Vilcabamba (Peru): the 2020 Salkantay event, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13584, https://doi.org/10.5194/egusphere-egu21-13584, 2021.
Addressing the question of whether Glacial Lake Outburst Floods (GLOFs) are changing in frequency and magnitude in modern times requires historical context, but suffers from incomplete GLOF inventories, especially in remote mountain regions. Here, we exploit high-resolution, multi-temporal satellite and aerial imagery combined with documentary data to identify GLOF events across the glacierized Cordilleras of Peru and Bolivia, using a set of diagnostic geomorphic features. More than 150 GLOFs are characterised and analysed, far exceeding the number of previously reported events. We provide statistics on location, magnitude, timing and characteristics of these events. Further, we describe several cases in detail and document a wide range of process chains associated with GLOFs. Our findings outline implications for regional GLOF hazard identification and assessment and provide solid basis for enhanced understanding GLOF occurrence under changing climate conditions and glacier retreat.
How to cite: Emmer, A., Cook, S., Wood, J. L., Harrison, S., Wilson, R., Diaz-Moreno, A., Reynolds, J. M., and Torres, J.: A new GLOF inventory for the Peruvian and Bolivian Andes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9744, https://doi.org/10.5194/egusphere-egu21-9744, 2021.
Glacial Lake Outburst Floods (GLOFs) are amongst the most common and high-magnitude natural hydrological disasters in high-mountain regions that have resulted in severe casualties and socioeconomic losses over the last century. Here, we integrate various data and methods to analyse and reconstruct the GLOF process chain involving the moraine-dammed proglacial lake ‒ Jinwuco (30.356°N, 93.631°E) in eastern Nyainqentanglha, Tibet, China, which occurred on 26th June 2020. This lake underwent rapid expansion in area from 0.2 km2 to 0.56 km2 (1965-2020), and subsequently shrank to 0.26 km2 after the GLOF. Topographic reconstruction and empirical relationships indicate that the GLOF had a volume of 10 million m3, an average breach time of 0.62 hours, and an average peak discharge of 5,390 m3/s at the dam. Pre- and post-event high-resolution satellite scenes reveal a large progressive debris landslide originating from western lateral moraine. This landslide which occurred 5-17 days before the GLOF was most likely triggered by extremely heavy, south Asian monsoon-associated rainfall in June. The time lag between the landslide and the GLOF suggests that pre-weakening of the dam due to landslide-induced outflow pushed the system towards a tipping point, that was finally exceeded following subsequent rainfall, snowmelt, a secondary landslide, or calving of ice into the lake. We back-calculate a part of the GLOF process chain, using the GIS-based open source numerical simulation tool r.avaflow, considering two scenarios: Scenario A - a debris landslide-induced impact wave with overtopping and resulting retrogressive erosion of the moraine dam; and Scenario B - retrogressive erosion due to pre-weakening of the dam without a major impact wave. Both back-calculated scenarios yield plausible results which are in line with empirically derived ranges of peak discharge and breach time. The breaching process is characterized by a slower onset and a resulting delay in Scenario B, compared to Scenario A. Our evidence, however, points towards Scenario B. The 2020 Jinwuco GLOF caused severe destruction of infrastructure (e.g. roads and bridges) and property losses in downstream areas (no fatalities were reported).
This study corroborates the clear role of continued glacial retreat in destabilizing the adjacent lateral moraine slopes, and directly enabling the landslide to deposit into the expanding lake body. As such, the GLOF process chain can be robustly attributable to anthropogenic climate change, while downstream consequences have been driven by recent development of infrastructure on exposed flood plains. Such glacial lake related process chains could become more frequent under a warmer and wetter future climate, calling for comprehensive and forward-looking risk reduction planning. We anticipate our findings will provide critical new process understanding on GLOF triggering mechanisms and these new insights will improve GLOF hazard and risk assessment frameworks, highlighting the need to consider both complex instantaneous and gradual process chains.
How to cite: Zheng, G., Mergili, M., Emmer, A., Allen, S., Bao, A., Guo, H., and Stoffel, M.: Landslide-GLOF cascade at the expanding Jinwuco in Tibet, 2020: a clear consequence of anthropogenic climate change , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2185, https://doi.org/10.5194/egusphere-egu21-2185, 2021.
Widespread retreat of glaciers has accelerated over recent decades in most mountain regions as a consequence of global warming, leading to rapid expansion of glacial lakes, bringing related risks.When water is suddenly released, Glacial Lake Outburst Floods (GLOFs) can devastate lives and livelihoods up to hundreds of kilometres downstream of their source. This threat is most apparent in High Mountain Asia (HMA), home to >200 million inhabitants, and where >150 GLOFs have been recorded from moraine dammed lakes alone. Here we reflect on our recent experience working across HMA to outline key learnings, challenges and perspectives in applying GLOF hazard and risk assessment at various scales, with an emphasis on how results have or can inform local response planning.
The number of large-scale assessment studies has increased exponentially over recent years, often giving inconsistent results in terms of what are considered potentially dangerous lakes. This makes it difficult for authorities and funding agencies to identify where more detailed hazard mapping and risk management strategies should be targeted, especially in cases where the science may not be aligned with local understanding and experience. We therefore recommend a consensus approach, drawing across multiple studies, and including the knowledge of local authorities to arrive at a final listing of high priority lakes which may be subject to further monitoring, Early Warning Systems and other response strategies. In our stakeholder interactions, we have particularly emphasised that GLOFs from even relatively small lakes can lead to significant damages when combined with other hazardous processes, e.g., the case of 2013 Chorabari GLOF combining with monsoon flooding and landslides in Northern India, or the 2016 outburst from Gongbatongshaco, Chinese Himalaya, Tibet, where erosion and bulking was significantly enhanced as a consequence of the Gorkha earthquake occurring a year earlier.
Looking to the future, several assessment studies have now combined modelling of glacier bed topography to identify where new lakes could emerge in the future, and even combined this information with changing exposure levels (e.g., planned hydropower development). However, there are challenges around communicating these uncertain future hazards and risks, and to what extent they should be considered in planning. In the transboundary Poiqu basin originating in Tibet, we have focussed on worst-case scenario modelling for such a future lake, demonstrating that flow depths and velocities would exceed the threat from current lakes, and the peak wave would reach the border with Nepal up to 20 minutes faster. Open questions remain around how triggering processes will evolve in the future. Most assessments currently focus on cascading process chains triggered by ice or rockfall, whereas under a wetter and warmer future climate, heavy rainfall and snowmelt as a direct or indirect trigger could become increasingly important. Further, major uncertainties arise from socio-economic developments and related changes in exposure and vulnerability, that could, in some regions, be the most significant drivers of future GLOF risk. Ultimately, forward-looking, GLOF hazard and risk assessment must ensure that response strategies remain robust in the face of ongoing environmental and societal change.
How to cite: Allen, S., Bolch, T., Frey, H., Zhang, G., Zheng, G., Mal, S., Chen, N., Sattar, A., and Stoffel, M.: Glacial lake outburst floods in High Mountain Asia: From large scale assessment to local disaster risk management, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14213, https://doi.org/10.5194/egusphere-egu21-14213, 2021.
The Hindu-Kush-Himalayan region is home to numerous glacial lakes. Some of these lakes could fail and produce hazardous Glacial Lake Outburst Floods (GLOF). GLOFs are primarily triggered by an avalanche or a rockfall entering the lake that generates an overtopping displacement waves. In the present study, we investigate the susceptibility of all lakes present in the Hindu-Kush-Karakorum (HKH) region (Randolph Glacier inventory region 14 and 15) to the dynamic mass movement (avalanche and rockfall). Avalanche and rockfall trajectories are developed considering various depths and “Minimum Look-Up Angle” (MLUA: a term used to define the avalanche runout distance). These trajectories are also validated against the results obtained from the Rapid Mass Movement Simulation (RAMMS) model. The mass movement of avalanche or rockfall along the major axis may enhance the wave run-up leading to a higher impact on the damming structure. Therefore, each susceptible lake is critically assessed for the angle of intrusion of a mass movement. The stability of the glacial lakes was also evaluated using the steep lake front area method to understand the associated hazard. Obtained results suggest that out of 3725 glacial lakes, 239 are susceptible to an avalanche when the mean avalanche depth is considered 50 m, and only 43 if the assumed mean avalanche depth is reduced to 10 m. Furthermore, the rockfall trajectories suggest that 343 lakes are susceptible to rockfall while considering MLUA of 17˚, which falls to 217 when MLUA is increased to 23˚. Overall, glacial lakes in the Central Himalayas were more susceptible to mass movement than the Karakoram, Western and Eastern Himalayas. We hope that our work will enable stakeholders to make a well-informed decision for hazard management in the Hindu-Kush-Himalayas. In addition to this, developed avalanche and rockfall trajectories will also help identify critical regions and hazard susceptibility structures.
How to cite: Dubey, S., Goyal, M., Sattar, A., and Haritashya, U.: Susceptibility of glacial lakes to avalanche and rockfall in the Hindu-Kush-Himalaya, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12475, https://doi.org/10.5194/egusphere-egu21-12475, 2021.
In May 2012, a sudden outburst flood along the Seti Khola river caused 72 fatalities and damaged infrastructure in the northern Pokhara Valley, Nepal. This destructive event raised concerns about possible future landslide- or glacier-surge-related outburst floods from the Higher Himalayas. The Seti Khola runs along one of the steepest topographic gradients in this mountain belt. The river is fed by the debris-covered Sabche glacier, Nepal’s only observed surging glacier, below the flanks of Annapurna III (c. 7500 m asl) and reaches Pokhara, the country’s second largest city, at about 850 m asl. Over a course of some 40 km, the Seti Khola shaped the Pokhara Valley’s distinctive landscape of unpaired, several tens of meters to >100-m high alluvial terraces that alternate with deep slot gorges of <1 km length, all mostly cut into deposits of medieval and earlier outburst and outwash deposits. These abrupt changes in channel cross section provide many potential locations of hydraulic ponding during floods. We present a reanalysis of the 2012 Seti Khola outburst flood, and combine field-based surveys of valley geometry, flood markers, and surface roughness (i.e. Manning’s n value estimates) with landform mapping from high-resolution satellite images and digital elevation models. These components form the input for a one-dimensional steady flow simulation in HEC-RAS that allows us to reconstruct the dynamics, stage height, and runout from the 2012 Seti Khola flood. Validated by both this recent and the catastrophic historic events, we use our model to simulate future scenarios of inundation by these infrequent but potentially highly destructive outburst floods and compare them to the Pokhara Valley’s recurring monsoonal floods.
How to cite: Fischer, M., Korup, O., Veh, G., and Walz, A.: Hydrodynamic modelling of outburst flood hazard in the Pokhara Valley, Nepal, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1260, https://doi.org/10.5194/egusphere-egu21-1260, 2021.
The presence of large and rapidly growing glacial lakes along the Himalayan Arc makes glacial lake outburst floods (GLOFs) a serious mountain hazard. While glacial lakes are mainly located in remote and unsettled mountain valleys, far-reaching GLOFs may claim lives and damage assets tens of kilometers downstream. Evaluating GLOF hazard is therefore of high importance, considering current and potential future climate-driven changes of glaciers and glacial lakes. A major concern in the Northeastern Indian Himalayan state of Sikkim is the damage potential these flood events can cause to hydropower plants and local vulnerable communities. This is particularly true for outburst floods potentially originating from the two lakes in Sikkim that are considered hazardous: the South Lhonak Lake and the Shako Cho Lake. Both lakes have been recognized in previous studies, and by local and state authorities, as being high priority sites for further monitoring and potential risk reduction measures. Recognizing the need for related risk reduction strategies to be based on robust scientific understanding, this study aims to combine remote sensing approaches with hydrodynamic flood modeling to identify key threats to lives and livelihoods.
This study also provides the first implementation of recently developed national guidelines on the management of GLOFs, where a detailed risk assessment including potential GLOF triggers, conditioning factors, and downstream impacts forms the scientific core. First results of only-water flow using HEC-RAS show that a high-potential scenario (dam breach depth = 40 m) produces flow depth and flow velocity up to 25 m and 9-12 m s-1, respectively, at Chungthang, a town located close to a major hydropower station, 62 km downstream of the lake. The fact that GLOF flow rheology is often changing as it propagates downstream, further modeling has been undertaken with r.avaflow, which can simulate the entire process chain from initial avalanche triggering, to dam erosion, and downstream flow propagation with a multi-phase modeling approach. Hence, we can evaluate the potential downstream impact in the case of a GLOF transitioning into a debris flow process. Our results provide flow hydraulics including flow velocities, flow heights, and total downstream inundation. These parameters will provide important insights for risk reduction strategies, such as early warning systems and land-use planning under current and future glacial conditions.
How to cite: Sattar, A., Allen, S., Frey, H., Huggel, C., and Mergili, M.: Modeling glacial lake outburst flood process chains in Sikkim Himalaya: Hazard assessment of two potentially dangerous lakes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10838, https://doi.org/10.5194/egusphere-egu21-10838, 2021.
With the substantial glacier mass reduction projected by the end of the century, the formation and rise of periglacial lakes has to be expected. Even though these changes often occur in remote areas, they can nevertheless have catastrophic impacts on populations and infrastructure through processes such as glacial lake outburst floods (GLOF). GLOFs are the result of complex geomorphic changes and subject to various timescales, thus urging the need for a multidimensional approach. The present study combines two approaches to analyze natural hazards in the secluded San Rafael National Park in Chilean Patagonia (North Patagonian Icefield). The Grosse glacier outlet was chosen after interpreting satellite imagery and historical pictures showing a historical emptying of a lateral lake, which was also supported by local testimonies. Dendrogeomorphology was primarily used with an automatic detection approach to identify possible dates of occurrence of past GLOFs at the Grosse outlet. A total of 105 disturbed Nothofagus trees were sampled highlighting 6 event years between 1958 and 2011. The second method aimed at complementing the tree-ring-based findings with UAV imagery acquired during fieldwork and the mapping of geomorphic evidence of past GLOFs. Huge boulders and deposits are one of the signs recognized as remnants of past lake outbursts and were thus used to differentiate small, rainfall-induced floods from high magnitude events. More precisely, through an object-based strategy, we mapped deposits and extrapolated a theoretical flow orientation. Whereas the first method allowed to select dates of potential events, the second facilitated identification and mapping of the spatial extent of past high-energy events. Analysis of imagery also allowed detection of the occurrence of a 200-m wide breach in the frontal moraine as well as the vanishing of a lateral lake estimated to be 1.8 × 106 m2 in the 1950s, which we date to 1958 using tree-ring records. When used together the two approaches can represent a valuable contribution to historical records and help future assessments of natural hazard at Grosse glacier, but also in other high-mountain environments.
How to cite: Gorsic, S., Muñoz-Torrero Manchado, A., Lopez-Saez, J., K. Allen, S., A. Ballesteros-Canovas, J., Rodríguez-Morata, C., Dussaillant, A., and Stoffel, M.: How can drone imagery and dendrogeomorphology contribute to GLOF hazard assessment in remote areas? A case study from Chilean Patagonia., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10821, https://doi.org/10.5194/egusphere-egu21-10821, 2021.
The southwestern part of Tibet in China is one of the hardest-hit areas where Glacier Lake Outburst Flood (GLOF) occurs frequently in the Moraine Lakes of Himalayas. In the face of the increasingly severe GLOF threat of Moraine Lakes, it is urgent to build a risk management and response process of moraine lakes GLOF in this region. Therefore, we propose a multi-module, process-oriented approach to GLOF risk response (Monitoring-Evaluation-Simulation), which integrates remote sensing, field surveys, Geographic Information Science (GIS), mathematical evaluation models, and hydrodynamic models to carry out the monitoring and analysis of GLOF, susceptibility evaluation, and numerical simulation work in Moraine Lakes. In the monitoring section (remote sensing and field surveys), we find that typical Moraine Lakes in southwestern Tibet continue to expand in area and are prone to GLOF, which is mainly due to significant area expansion, large-scale ice/avalanches and landslides, and overflow or seepage at the terminal moraine dam. In the assessment part, based on the susceptibility evaluation factor of the glacial lake obtained by monitoring. We creatively use the grey correlation model to filter the GLOF susceptibility evaluation factors, so that the constructed GLOF susceptibility evaluation model has achieved good results (the model evaluation accuracy rate reached 84%, and the AUC value reached 0.874). In the modeling part, the GLOF modeling was carried out for the glacial lakes with high GLOF susceptibility determined by the assessment. It is also the first time that the FLO-2D model is used to construct the GLOF process of a typical Moraine Lake in the Himalayas. The simulation results show the effective simulation capability of the FLO-2D model (the simulated flow depth and flow velocity errors are both within 10%). In short, realizing the organic combination of monitoring, evaluation and simulation are one of the main advantages of the "Monitoring-Evaluation-Simulation" method. This approach effectively supports the prevention and control of GLOF in Moraine Lakes in southwestern Tibet and provides a new application idea for the risk management and response of GLOF in regional Moraine Lakes.
How to cite: Wang, X., Chen, G., Dai, X., Zhao, J., Liu, X., Gao, Y., Zhang, J., Chen, Y., Li, X., Qin, W., and Wang, P.: Risk management and response process of moraine lakes GLOF in southwestern Tibet (China), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5186, https://doi.org/10.5194/egusphere-egu21-5186, 2021.
Mountain glaciers and permafrost are among the most evident geomorphological tracers of climate change. In the last decades, they showed a growing and faster response also at very high elevations, leading to increased instability of the Alpine landscape. In the meanwhile, they became of great interest also for their possible interactions with human activities and infrastuctures.
On the highest massif of the Alps, as for example the Monte Rosa, this interaction is mainly represent by the one with mountaineering activities. The top of Gnifetti Peak (4554 m a.s.l.), with the Capanna Margherita hut (the highest in Europe), is under investigation to better understand the effects of global warming on hut stability and mountaineering routes safety. Thanks to the cooperation between the Italian Alpine Club (CAI), University of Turin (UniTo), Politecnico di Milano (PoliMi) and IMAGEO srl, a first assessment of geological and glacial settings of hut surroundings have been performed on 2019. Data collection continued on 2020, by means of comparative analyses designated to: a) identify the relevant geomechanical features for rock mass stability; b) verify permafrost related instabilities; c) reconstruct the ice-covered morphology of the Punta Gnifetti peak; d) calculate rock-building interactions. Here below the related results:
1) A 3D model of the area has been obtained by integrating helicopter-borne photogrammetry with terrestrial laser scanner surveys.
2) Glacier thickness at the Colle Gnifetti has been established thanks to GPR survey.
3) From the comparison of a large number of historical pictures a first multi-temporal stability analysis highlighted sector of greater instability. Results of this work are freely available on the website www.geositlab.unito.it/capanna .
4) The geomechanical features of the rock mass below and around the hut have been retrieved from the analysis of the dense point cloud provided by terrestrial laser scanner integrated with direct field investigations.
5) Constructive drawing of the hut have been obtained from the terrestrial laser scanner point cloud integrated with manual measurements taken inside the structure.
6) 3D numerical modelling are going to be applied in order to simulate the interactions between the hut and the foundation rock on the base of the above data.
The ongoing activities are addressed to a detailed study of more vulnerable sectors of the Punta Gnifetti to better understand morphodynamics and possible interactions with mountaineering activities. This will be performed through a two-way investigation. On one hand, a link with alpine guides and mountain hut keepers has been established, in order to have “sentries” ready to report instabilities and detect new hazards and risks. On the other hand, a monitoring network will be installed around Capanna Margherita in order to collect data on weather, glacier and permafrost conditions.
How to cite: Giardino, M., Montani, A., Tamburini, A., Calvetti, F., Martelli, D., Salvalai, G., Tognetto, F., and Perotti, L.: Climate change and cryosphere in high mountains: updates from the Capanna Margherita hut study case (Punta Gnifetti, Monte Rosa Massif, Pennine Alps), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15577, https://doi.org/10.5194/egusphere-egu21-15577, 2021.
Environmental policies have the purpose to protect ecosystems in their structure and function to maintain the ecosystem services they provide. They are based on scientific knowledge at the time they are established, and rarely are those assumptions revisited or is the effectiveness of these policies in protecting or promoting a particular ecosystem service tested. In this study, we revisit the first Swiss Federal Forest Law which protects mountain forests as a means of protection from natural hazards. It was established in 1876 following catastrophic flood events to preserve and restore the protective service of mountain forests by prohibiting clear-cutting and an excessive use of forests. Here, we provide a conceptual and methodological framework to explore the effects of the Forest Law on flood occurrence based on insights from preliminary results of a feasibility study. For the conceptual framework, we summarize the current scientific knowledge on i) forest effects on hydrological regimes and their protection service against floods, ii) reasons for reforestation in mountains and how the law may have contributed, and iii) other watershed changes affecting both reforestation and the forest-runoff interaction. We then develop the methodological framework based on insights from a case study on the Upper Rhone catchments, which serves as a prototype of an interdisciplinary methodological approach to answer the question of whether a forest protection law can serve as a means of flood protection. We explore the feasibility of answering this question given data are at different scales and resolutions. We suggest modeling to fill data gaps and discuss collaboration among natural and social sciences. Specifically, we propose that both natural and social scientists need to collaborate, with frequent exchange, to collect the data necessary to evaluate the relationship between legal forest protection and flood occurrence. We found an environmental historian is needed to evaluate if changes in forest cover can be attributed to mandates by the law, or rather cultural and societal developments. Further, a forest scientist or engineer in collaboration with a hydrologist will need to adapt and improve hydrological models that specifically include forest cover and structure. All scientists need to collaborate to find the information on historical and current forest cover (e.g., maps, postcards, orthophotos) and floods (e.g., archival documents, journal, newspapers, hydrological stations). Our case study indicates that data to answer the overarching question may be available and emphasizes the necessity of a true interdisciplinary approach allowing for consideration and combination of a variety of data sources and different temporal and spatial scales. The interdisciplinary framework we developed can serve as example for other ecosystem services, where similar questions on the effects of environmental practices and policies arise.
How to cite: Rüegg, J., Moos, C., Gentile, A., Luisier, G., Elsig, A., Prasicek, G., and Otero, I.: Investigating the concept of mountain forest protection and management as a means for flood protection, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8004, https://doi.org/10.5194/egusphere-egu21-8004, 2021.
Mountains cover about a quarter of the Earth’s land surface and are home to or serve a substantial fraction of the global population with essential ecosystem services, in particular water, food, energy, and recreation. While mountain systems are expected to be highly exposed to climate change, we currently lack a comprehensive global picture of the extent to which environmental and human systems in mountain regions have been affected by recent anthropogenic climate change.
Here we undertake an unprecedented effort to detect observed impacts of climate change in mountains regions across all continents. We follow the approach implemented in the IPCC 5th Assessment Report (AR5) and follow-up research where we consider whether a natural or human system has changed beyond its baseline behavior in the absence of climate change, and then attribute the observed change to different drivers, including anthropogenic climate change. We apply an extensive review of peer-reviewed and grey literature and identify more than 300 samples of impacts (aggregate and case studies). We show that a wide range of natural and human systems in mountains have been affected by climate change, including the cryosphere, the water cycle and water resources, terrestrial and aquatic ecosystems, energy production, infrastructure, agriculture, health, migration, tourism, community and cultural values and disasters. Our assessment documents that climate change impacts are observed in mountain regions on all continents. However, the explicit distinction of different drivers contributing to or determining an observed change is often highly challenging; particularly due to widespread data scarcity in mountain regions. In that context, we were also able to document a high amount of impacts in previously under-reported continents such as Africa and South America. In particular, we have been able to include a substantial number of place-based insights from local/indigenous communities representing important alternative worldviews.
The role of human influence in observed climate changes is evaluated using data from multiple gridded observational climate products and global climate models. We find that anthropogenic climate change has a clear and discernable fingerprint in changing natural and human mountain systems across the globe. In the cryosphere, ecosystems, water resources and tourism the contribution of anthropogenic climate change to observed changes is significant, showing the sensitivity of these systems to current and future climate change. Furthermore, our analysis reveals the need to consider the plurality of knowledge systems through which climate change impacts are being understood in mountain regions. Such attempts at inclusivity, which addresses issues of representation and justice, should be deemed necessary in exploring climate change impacts.
How to cite: Huggel, C., Allen, S. K., Bhatt, I. D., Chakraborty, R., Drenkhan, F., Marchant, R., Morin, S., Niggli, L., Ochoa Sánchez, A. E., Postigo, J., Razanatsoa, E., Rudloff, V., Cuni Sánchez, A., Stone, D., Thorn, J., and Viviroli, D.: Anthropogenic climate change detected in natural and human systems of the world’s mountains, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2257, https://doi.org/10.5194/egusphere-egu21-2257, 2021.
Protected areas play an important role in ecosystem conservation and climate change adaptation. However, no systematic information is available on the protection of high elevation freshwater ecosystems (e.g. lakes, glacierized catchments and streams), their biodiversity and ecosystem services. Here we addressed this issue by reviewing literature and analyzing maps of protected areas and freshwater ecosystems in the tropical Andes. Overall, our revision and inventory indicate: 1) seven national parks were created with the objective of water resources protection, but they were not designed for freshwater conservation (i.e., larger watersheds), and mainly protect small ecosystems. Furthermore, the creation of new local protected areas was needed for water resources conservation; 2) we quantified 12% and 31% of lakes and glacial lakes are protected, respectively. Around 12% of the total stream length is protected. First-order streams predominate in the study area, of which 14% are protected. Furthermore, 29% of glacierized catchments (average surface of 677 km2)are protected, and 46% of the total glacier area is protected. We quantified 31 Ramsar sites; 3) high-value biodiversity sites have not been protected, and ecosystems services information is limited. This review highlights the need for future research to fill knowledge gaps for effective freshwater conservation actions.
How to cite: Quenta, E., Crespo-Pérez, V., Mark, B., Gonzales, A. L., and Kulonen, A.: Mountain freshwater ecosystems and protected areas in the tropical Andes: insights and gaps for climate change adaptation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3448, https://doi.org/10.5194/egusphere-egu21-3448, 2021.
In the tropical Andes and adjacent lowlands, human and natural systems often rely on high-mountain water resources. Glaciated headwaters play an essential role in safeguarding water security for downstream water use. However, there is mounting concern particularly about long-term water supply as the timing and magnitude of glacier meltwater contribution to river streamflow become less reliable with rapid glacier shrinkage. This concern matches an increase in water demand from growing irrigation, population and hydropower capacity in combination with high social-ecological vulnerabilities threatening sustained water security. Despite important progress in assessing the impacts of glacier shrinkage and consequences for meltwater availability, little is known about the associated hydrological risks and how they propagate downstream. Therefore, integrated approaches are needed that combine a detailed picture of the meltwater propagation through the terrestrial water cycle with human vulnerabilities and exposure to water scarcity. However, the complex topographic and sociocultural setting including scarce data, limited local capacities and frequent water conflicts hamper a more thorough process understanding and water security assessment at a basin scale.
Under high complexity and uncertainty, we propose a coupled risk framework combining water scarcity hazards, exposed people and multiple human vulnerabilities to address these limitations. An important aspect of the framework is the recognition of knowledge from indigenous and rural communities that can potentially be integrated into current scientific baselines and innovative adaptation debates. Our framework interlinks a broad set of hydroclimatic, socioeconomic and water management variables at unprecedented detail. We put particular emphasis on the quantification and understanding of multidimensional vulnerabilities as a key element for evaluating the enabling effects of these impacts in social-environmental systems. However, the assessment of corresponding vulnerabilities might not be relevant if the degree of the systems’ exposure is not sufficiently addressed. Therefore, we further analyse the interplay of the diverse variables and critical system thresholds that determine the dimensions and spatiotemporal patterns which enable meaningful assessments of cascading processes and interconnected risks to water scarcity.
Our risk framework provides a thorough baseline to support assessments of future water availability for guiding climate change adaptation, water management, and governance in rapidly changing mountain basins. Nonetheless, remaining uncertainties and limited understanding relate to the availability of local data and highlight the need for additional data collection. Lastly, we identify specific opportunities to explore the use of nature-based solutions, such as source water and wetland protection, in combination with a strong engagement of local communities and policy makers as an efficient pathway to cope with emerging risks to water scarcity in glacier-fed river basins.
How to cite: Drenkhan, F., Martínez, E., Zogheib, C., Ochoa-Tocachi, B. F., and Buytaert, W.: Emerging water scarcity risks in tropical Andean glacier-fed river basins, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3487, https://doi.org/10.5194/egusphere-egu21-3487, 2021.
Physical, biological, and human systems in mountain regions are highly sensitive to climate change due to strong feedbacks and low resilience. Detection of changes and attribution of them to climate and non-climate drivers provides ongoing monitoring of complex interactions of coupled natural and human systems and improving scientific assessments that inform mitigation and adaptation practices. In the IPCC 5th Assessment Report published in 2014, Central and South America was the region with the least evidence available for detection and attribution (D&A) of climate change impacts. Since then, much more evidence has accumulated due to an increasing number of studies detecting impacts in the Andean region. In this study, we therefore performed a systematic literature review of climate change impacts and made a local D&A expert impact assessment for a total of 12 natural and human systems in the Andes. We found the following confidence levels of detection and attribution of each impact for each system: medium and high, respectively, for energy; high and high, for snow and ice, tourism, and cultural values; high and medium for terrestrial and aquatic ecosystems, disasters, human health and migration; and medium and medium for agriculture and water systems. A total number of 65 sample impacts (in aggregate or case study form) could be attributed to climate change. Climate change was especially important in glacio-hydrological systems (49%) and terrestrial ecosystems (15%). Among the impacts that could be attributed to climate change with high confidence, snow and ice system dominated. About half of the total impact samples were attributed with medium confidence, of which 35% corresponded to water systems and 16% to agriculture. Finally, 14% of all impacts were assessed with low attribution confidence. Important results include: (1) glacier retreat leads to important cascading effects affecting most of the systems in the Andes; these impacts were primarily attributed to temperature increase caused by anthropogenic climate change; (2) numerous terrestrial and aquatic Andean ecosystems have been affected by climate change (e.g. upward plant colonization, changes in the abundance and distribution of species), and most of these impacts could be attributed to anthropogenic climate change; and (3) community changes and loss of cultural values are among the strongest impacts of human systems that were attributed to climate change; a broad set of studies detected that Andean communities perceived changes in their highly preserved long-standing cultural and spiritual rituals and cosmovision. These findings are key to understand current climate change impacts in the Andean region, and to advance our understanding of complex interactions of coupled natural and human systems in order to put particular attention on integrated scientific assessments and leverage local decision-making and management practices.
How to cite: Ochoa-Sánchez, A., Drenkhan, F., Stone, D., Mendoza, D., Gualán, R., and Huggel, C.: Natural and human systems of the Andes under climate change: local detection and attribution assessment of impacts in physical, biological and human systems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4725, https://doi.org/10.5194/egusphere-egu21-4725, 2021.
Mountains are a critical source of water and home to a large proportion of the world’s population. Cryospheric and hydrological changes combined with increasing water demand are impacting water availability, livelihoods and cultural values, threatening long-term water security of downstream populations. Here, we present a global systematic review in which 83 peer-reviewed articles were critically evaluated to unravel and assess different types of adaptation measures that have been undertaken to manage water stress. We observe that changes in glacier extent and snowfall amount are the main cryospheric changes motivating adaptations. However, changes in precipitation patterns, such as increasing extremes or alterations of the rain-snow line, which lead to both increasing water stress and seasonal flooding or glacier lake outburst floods (GLOFs), and are also observed to be important motivators of adaptive actions. The main sectors affected by hydrological and cryospheric changes are agriculture, tourism, hydropower generation and health and safety. To reduce risks of water scarcity and water-related disasters, and to enhance the resilience of human and natural systems, a broad set of adaptation measures have been implemented in the world’s mountain regions. Such adaptations include crop diversification, new irrigation practices, dams and water storage infrastructure, training programs and the establishment of Early Warning Systems, artificial snow making, shifts to non-snow-based tourism, and changes to cultural practices. We find that globally the most commonly used adaptation practices correspond to the improvement of water storage infrastructure, agricultural and irrigation practices, economic diversification and water governance and laws. However, our systematic review reveals these and other adaptation actions have strong regional variation. For example, adaptation in the agricultural sector is most prevalent in Africa, Asia and South America; while in Europe, Australia and New Zealand responses in the tourism sector are more common. Socio-ecological trade-offs associated with adaptations are often reported. For example, the promotion of snow-making reduces socio-economic vulnerability but adds pressure on water resources and environment.
However, successful implementation of adaptation measures are limited by a diverse set of factors. This includes reduced capacities and resources in infrastructure maintenance, mismanagement, conflicts and mistrust in government together with lack of funding and insufficient collaboration between stakeholders as well as delayed implementation of laws and mountain development programs. Moreover, extreme events and climate change impacts together with discontinuities and errors in climate data need to be considered. In order to address or overcome these limitations, it is important to raise awareness of local communities about climate change and to demonstrate the positive effects of adaptation measures and environmental laws; increase funding for mountain programs and motivate combined activities of governments and stakeholders to build their trust on each other.
How to cite: Aggarwal, A., Frey, H., McDowell, G., Drenkhan, F., Nuesser, M., Racoviteanu, A., and Hoelzle, M.: Adaptation to climate change induced water stress in major glacierized mountain regions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5033, https://doi.org/10.5194/egusphere-egu21-5033, 2021.
Mountain permafrost in Asia incorporates permafrost in the mountains of the Hindu Kush Himalayan region, Central Asia, Russia, Mongolia, Qinghai Tibetan plateau and other mountain ranges in China. Changes in climate variables in recent decades have considerably influenced permafrost in these regions and produced vivid impacts. While climate change impacts on mountain permafrost in the alpine regions of Europe, US and Canada are relatively well documented, records about mountain permafrost in Asia are mostly available for the Qinghai Tibetan plateau region and a few other mountain ranges in China. Considerably little information is available for the Hindu Kush Himalayan region and other mountain ranges in Asia. This systematic review analyses climate change related impacts and adaptation in mountain permafrost regions of Asia and attempts to evaluate the status of knowledge based on peer-reviewed journal publications. Impacts on hydrology, geomorphology and ecology were examined and resulting socioeconomic effects were considered. Additionally, ongoing and potential adaptation practices were explored. Warming climate has been found responsible for a gradual shift of the lower limit of mountain permafrost in the region. Increased probabilities of mass wasting events due to reduced slope stability, changes in composition and quality of fresh water resources, irregularities in seasonal flows, changes in permafrost ecosystems and contemporaneous need for the protection of engineered constructions were identified as some of the key impacts. There is a high necessity for increased understanding of mountain permafrost and well-designed response actions to evaluate processes and interactions influencing changes in the natural environment and subsequent effects on sustainable living conditions. Therefore, suitable risk management practices need to be designed with a proper consideration of the anticipated future dynamics of climate, economy and society.
How to cite: Baral, P. and Allen, S.: Using systematic review to analyse climate change impacts and adaptation associated with mountain permafrost, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9381, https://doi.org/10.5194/egusphere-egu21-9381, 2021.
The mountains of Central Asia, extending over 7000 m a.s.l. and accommodating diverse and complex natural and managed systems, are very vulnerable to climate change. They support valuable environmental functions and provide key ecosystem goods and services to the arid downstream regions which strongly depend on the melting snowpack and glaciers for the provision of water by the transboundary rivers starting in the mountains. Strong climate change adaptation (CCA) action is required to increase resilience of the vulnerable, low-income communities in the region. Our knowledge of the CCA actions in the mountains of Central Asia is limited in comparison with other mountainous regions. The aim of this study is to assess the existing adaptation projects and publications and to identify gaps in adaptation efforts by conducting a systematic review of the peer-reviewed literature published in English language. To be selected, the papers had to comply with the following criteria: (i) publication between 2013 and 2019; (ii) explicit focus on CCA in the mountain ranges of Central Asia; (iii) explanation of adaptation options; (vi) a clear methodology of deriving suitable adaptation options. Following the initial screening and subsequent reading of the publications, complying with the specified criteria, 33 peer-reviewed articles were selected for final analysis. This is considerably lower than the number of publications on the European Alps, Hindu-Kush – Himalayas, and the Andes. The number of publications on Central Asian mountains has declined since 2013.
The research is heavily focused on the problem of water resources, especially water availability at present and in the future 70 % of the analysed papers addressing these issues. These are followed by the papers considering adaptation in agriculture and in managing biodiversity. A critical finding is the lack of publications on adaptation to hazards and disasters including glacier outburst floods, mudflow, and landslides which are common and comparatively well-researched hazards in the Central Asian mountains, experiencing rapid deglaciation. About 50 % of the papers address the transboundary nature of the impacts of climate changes on water resources and land management reflecting the transboundary nature of the Central Asian catchments and the tensions which exist across the region but are especially prominent in the Aral Sea basin.
We conclude that while there is ample evidence of climate change and its impacts in the mountains of Central Asia and many publications mention the need for adaptation, a very limited number of publications explicitly focus on CCA and how it can be delivered.
How to cite: Saidaliyeva, Z., Muccione, V., Shahgedanova, M., Bigler, S., and Adler, C.: Adaptation to climate change in the mountain regions of Central Asia: Assessment of the current knowledge, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15303, https://doi.org/10.5194/egusphere-egu21-15303, 2021.
GuMNet is a facility that operates continuous observation of the atmosphere, surface and subsurface at the Sierra de Guadarrama, located 50 km north-northwest of Madrid. It is composed of 10 real–time automatic stations and attempts to promote research on weather, soil thermodynamics, boundary layer physics, impacts of climate change on climate and ecosystems and air pollution in Sierra de Guadarrama. This infrastructure represents a first step into providing a unique observational network in a high protected environment that can serve a wide range of scientific and educational interests and also management.
The stations are located at heights ranging from 900 m.a.s.l. to 2225 m.a.s.l. Every station has been settled in open areas, except for one that can be found in a forested zone. High altitude sites are focused on periglacial areas, while low elevation sites are placed in pasture environments. The atmospheric instrumentation includes sensors used for the measurement of air temperature, air humidity, 4-component radiation, solid and liquid precipitation, snow depth, wind speed and wind direction. For the subsurface measurements, soil temperature and humidity sensors have been placed in 9 trenches up to 1 m depth and 12 boreholes up to 2 m and 20 m depth. One of the lowest stations has been equipped with a 3D sonic anemometer that includes a CO2/H2O analyzer. Wind profiles and eddy-covariance will be sampled, which is important for energy and water vapor exchanges. A portable station has also been equipped with a 3D sonic anemometer, which will enable the comparison between measurements at both sites. The entire network is connected via general packet radio service (GPRS) to the management software at the central laboratory located at the Campus of Excellence of Moncloa (Madrid, Spain).
The database generated by GuMNet is accessible through request and allows for developing studies concerning environmental and climate change in middle and high mountain areas. This valuable source of data aims at generating a space for scientific collaboration with other national and international institutions. The diversity of potential uses of the GuMNet observational network will be very useful in education at every level.
Website and contact: http://www.ucm.es/gumnet/
How to cite: González-Rouco, F. and the The GuMNet Consortium Team: GuMNet – The Guadarrama Monitoring Network initiative (Spain), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7457, https://doi.org/10.5194/egusphere-egu21-7457, 2021.
The intensity of the current climate change has strong consequences on high mountain tourism activities. Winter activities are currently the most studied (ski industry). However, the consequences of environmental changes are also strong in summer, as geomorphological processes are enhanced at high elevation. The Mont Blanc Massif (Western Alps) is a particularly favourable terrain for the development of research about these processes. Emblematic high summits (28 of the 82 peaks > 4000 m of the Alps), dozens of glaciers, strongly developed tourism with summer/winter equivalence, active mountaineering practice, etc. all contribute to the interest of studying this geographical area. A lot of work has been carried out on glaciological and geomorphological issues. These studies, which deal with "physical" impacts of the climate change on the high mountains, are also supplemented by studies of their consequences on human societies, as its impacts on practices such as mountaineering or glacier tourism. Risk-related issues are also taken into account with, for example, the stability of infrastructure (huts, ski lifts) or the impact of glacial shrinkage on the formation of new and potentially hazardous lakes. Accordingly, the aims of our presentation are to show the extent of the research developed on climate change in the Mont Blanc massif and how social and environmental sciences are interlinked to provide a holistic vision of the issues of this territory. As these experiments are not exactly interdisciplinary experiments, this presentation also aims to discuss the points that need to be further developed in order to promote inter- and trans-disciplinary research.
How to cite: Salim, E., Mourey, J., Ravanel, L., Duvillard, P.-A., Cathala, M., Magnin, F., Deline, P., Kaushik, S., Guillet, G., Gallach, X., and Olhasque, M.: Understanding the impacts of climate change on high mountain practices: the case of the Mont Blanc massif through an interdisciplinary approach, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1729, https://doi.org/10.5194/egusphere-egu21-1729, 2021.
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