Annals of Glaciology

Journal: Annals of Glaciology

Abbreviation

Ann Glaciol

Publisher

Cambridge University Press

ISSN

0260-3055
1727-5644

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Publications 1 - 10 of 15

Vanished glaciers of the Swiss Alps: An inventory-based assessment from 1973 to 2016
Linsbauer, Andreas; Huss, Matthias; Hodel, Elias; et al. (2025)
Annals of Glaciology
This study presents the first nationwide assessment of vanished glaciers in Switzerland. By comparing the Swiss Glacier Inventories SGI1973 and SGI2016, we identify 1019 vanished glaciers, representing more than 40% of all glaciers inventoried in 1973 and accounting for 13% (47±3 km²) of total glacier area loss. Glacier disappearance was most widespread along the main Alpine divide, in regions with relatively low peak elevations. Most vanished glaciers were very small (<0.10 km²) and steep, south- or east-facing glaciers more often vanished with respect to the initial glacier distribution. In the 2300-2550 m elevation band, vanished glaciers contributed over 30% of total area loss. Regionally, the Rhine basin hosts the largest number of vanished glaciers (423), while the Po (39%) and Danube (55%) basins have the highest share of glaciers disappearing with respect to the initial number. These findings underscore the relevance of systematically including vanished glaciers in change assessments. With a new inventory underway and two extreme melt years in 2022 and 2023, this study provides a benchmark for tracking continued glacier extinction in the Swiss Alps.
Continuous monitoring of a glacier's extinction
Huss, Matthias; Fischer , Mauro; Linsbauer , Andreas; et al. (2025)
Annals of Glaciology
Pizolgletscher, Swiss Alps, was already a very small glacier when the monitoring of length change was initiated 130 years ago. In situ mass balance measurements at seasonal resolution began in 2006. During the last 18 years, the glacier has lost 98% of its volume and is considered extinct since 2022. However, a tiny remnant of ice of a few thousand square metres is preserved under rockfall debris. The case of Pizolgletscher allows tracking the extinction of a glacier with a comprehensive long-term observational series. Furthermore, the vanished glacier has a touristic and cultural significance, as exemplified by a commemoration ceremony held in 2019. Here, detailed monitoring data sets (mass balance, area, volume, length) are presented that shed light on the processes of glacier disintegration before ultimate disappearance. Comparison to regional mass balance variations indicates that the signal from very small glaciers can remain representative at larger scales even during the final phase of a glacier's lifecycle.
Snow and slush on floating lake ice
Röthlisberger, Hans (1983)
Annals of Glaciology
The behaviour of a floating sheet of lake ice was investigated for the case when it becomes loaded by a layer of fresh snow which is later soaked with water. This latter condition interferes with the traditional horse races of St Moritz, which are held on the lake each year. A piezometric precision gauge which measures accurately the vertical movements of the floating ice relative to the free surface of the lake is described. The level of the lake, in turn, oscillates, depending on the use of water by the local power company. Detailed measurements from the winter of 1978-79 are presented, showing that the piezometric level rises in direct response to precipitation, and that it rises further when the snow becomes soaked with water. With a simple model it is shown that the ultimate level is a function of the snow density, and it is concluded that immediate compaction of falling snow is an appropriate measure to reduce the amount of water entering the snow. It is very unlikely that the oscillations of the level of the lake caused by the demands of the power company have an influence on the slush problem.
Using video detection of snow surface movements to estimate weak layer crack propagation speeds
Simenhois, Ron; Birkeland, Karl W.; Gaume, Johan; et al. (2025)
Annals of Glaciology
Dry-snow slab avalanches release due to crack propagation in a weak snow layer under a cohesive snow slab. Crack propagation speeds can provide insights into the potential size of avalanches and inform fracture and avalanche release models. Despite their importance, slope-scale crack speed measurements from real avalanches are limited. Further, most existing slope-scale measurements utilize the appearance of slab fractures on the snow surface. However, we have no evidence that the appearance of surface cracking is a good indicator of the weak layer crack propagation tip. Here we present a novel method to estimate crack propagation speed from snow surface movements in avalanche videos. Our technique uses changes in frame pixel intensity, allowing us to detect the location of weak layer cracks well before slab fractures appear on the snow surface. We use field experiments and numerical simulations to validate our method before applying it to five avalanches. Our estimates show that cracks propagate faster up and down the slope than in the cross-slope direction; this suggests that different propagation regimes likely govern crack propagation up/down the slope, cross-slope and in flat terrain.
Geothermal effects of 18 ka BP ice conditions in the Swiss plateau
Haeberli, Wilfried; Rellstab, Werner; Harrison, William D. (1984)
Annals of Glaciology
Quaternary surface temperature and ice conditions have lowered today’s temperatures in the uppermost 1 to 2 km of the Earth’s crust in the Swiss plateau by about 5 to 6°C in regions of formerly temperate glacier beds, and these effects were even greater on temperatures in formerly periglacial regions. Effects of latent heat exchange during the formation and thawing of ice-rich permafrost in high-porosity sediments enhance the effects of heat diffusion in low-porosity rock. The influence of underground ice formation, however, seems to be limited. This is due both to the limited thickness of high-porosity sediments and to the fact that high post-glacial surface temperatures in the Swiss plateau shortened the thaw time of ice-rich permafrost which formed at the time of maximum glaciation (18 ka BP). The greatest effects of ice conditions in 18 ka BP may therefore be expected outside the plateau in Alpine valleys. Here, advection of cold ice through glacier flow may have cooled high-porosity sediments of considerable thickness well below 0°C.
Temperature and accumulation of high altitude firn in the Alps
Haeberli, Wilfried; Alean, Jürg (1985)
Annals of Glaciology
Data on temperature and accumulation of high altitude firn in the Alps are compiled and discussed. Firn temperature varies with incoming radiation (slope aspect) at a given altitude. The altitudinal gradient of temperature in highly permeable firn bodies appears to be about twice as high as the mean lapse rate of air temperature. “Cold infiltration” takes place above about 3500 m a.s.l. Firn temperatures on the highest peaks are around -15°C. Accumulation (net balance) also decreases with increasing altitude from about 3m H2O at 3500 m a.s.1. to around 0.5 m H2O at wind exposed sites between 4300 and 4800 m a.s.l. Probably this is strongly due to wind erosion and topographical effects. However, temperature and accumulation not only appear to be interrelated, but also seem to be positively correlated to the heat applied to the surface. Assuming the observed altitudinal gradients have remained constant in time, it can be estimated that high altitude firn bodies have become considerably warmer since the last century. CO2-induced atmospheric warming could lead to a drastic change in (he mass turnover and flow activity of high glaciers, in wind-exposed places where wind erosion of the snowpack becomes a controlling factor of accumulation.
Influence of slab depth spatial variability on skier-triggering probability and avalanche size
Meloche, Francis; Guillet, Louis; Gauthier, Francis; et al. (2024)
Annals of Glaciology
Spatial variability of snowpack properties adds uncertainty in the evaluation of avalanche hazard. We propose a combined mechanical-statistical approach to study how spatial variation of slab depth affects the skier-triggering probability and possible release size. First, we generate multiple slab depth maps on a plane fictional slope based on Gaussian Random Fields (GRF) for a specific set of mean, variance and correlation length. For each GRF, we derive analytically the Skier Propagation Index (SPI). We then simulate multiple skier tracks and computed the probability based on the number of skier hits where SPI is below 1. Finally, we use a depth-averaged material point method to evaluate the possible avalanche size for given slab depth variations. The results of this analysis show that large correlation lengths and small variances lead to a lower probability of skier-triggering as it reduces the size and the number of areas with low slab depth. Then, we show the effect of skiing style and skier group size on skier-triggering probability. Spatial variability also affects the possible avalanche size by adding stress fluctuation causing early or late tensile failure. Finally, we demonstrate with our models the well-known relationship between the probability and the size in avalanche forecasting.
Mapping the distribution of buried glacier ice - An example from Lago delle Locce, Monte Rosa, Italien Alps
Haeberli, Wilfried; Epifani, F. (1986)
Annals of Glaciology
Techniques for mapping the distribution of buried glacier ice are discussed and the results, from a study carried out within the framework of flood protection work in the Italian Alps, are presented. Bottom temperatures of the winter snow cover (BTS) primarily indicate the heat flow conditions in the underlying ground and mainly depend on the presence or absence of an ice layer beneath the surface. Determination of BTS values is therefore an inexpensive method for quickly mapping the near-surface underground ice in areas where there is 1 m or more of winter snow cover. At greater depths, and/or when more detail is required, geoelectrical resistivity soundings and seismic refraction soundings are most commonly used to investigate underground ice. A combination of the two sounding techniques allows the vertical extent and the main characteristics (frozen ground, dead glacier ice) to be determined in at least a semi-quantitative way. Complications mainly arise from irregularity in the horizontal extension of the studied underground ice bodies, and they may have to be overcome by expensive core drillings and borehole measurements. Widespread occurrence of buried glacier ice was observed in morainic deposits, surrounding an ice-dammed lake near Macugnaga, Italy.
Frequency and characteristics of glacier floods in the Swiss Alps
Haeberli, Wilfried (1983)
Annals of Glaciology
Damage due to glacier floods in the Swiss Alps occurs about once every two years at present, despite the pronounced retreat of glaciers during the twentieth century and the installation of many water reservoirs, which act as flood retention basins. Over half (60 to 70%) of the observed floods are caused by outbursts of marginal glacier lakes or sudden breaks of ice dams, and 30 to 40% by ruptures of water pockets. In a glacierized mountain region as densely populated as the Swiss Alps, even debris flows triggered by outbursts of very small water masses may be dangerous. Historical information about glacier floods in the Swiss Alps, although incomplete and heterogeneous, is used as an empirical basis for an attempt to recognize potential hazards at an early stage by considering outburst processes, volumes of water involved, potential peak-discharge values, lithology and inclination within the reach of glacier streams.
Potential and challenges of depth-resolved three-dimensional MPM simulations: a case study of the 2019 'Salezer' snow avalanche in Davos
Kyburz, Michael Lukas; Sovilla, Betty; Bühler, Yves; et al. (2024)
Annals of Glaciology
Avalanche modeling is an essential tool to assess snow avalanche hazard. Today, most popular numerical approaches adopt depth-averaged equations. These methods are computationally efficient but limited in capturing processes occurring in the flow depth direction, e.g. erosion or deposition, which are often considered using ad hoc parameterizations or neglected completely. However, processes such as snow erosion, can crucially influence flow dynamics and run-out and are often not negligible. We address these issues by using a new three-dimensional (3-D) model, based on the material point method and finite strain elastoplasticity. To assess the possibilities and challenges associated with these highly detailed but computationally expensive calculations, we simulated the 'Salezer' snow avalanche that released in Davos, Switzerland in 2019. To reproduce the event in our simulations, we use the release areas mapped in a photogrammetric drone survey and estimate the snow conditions on the day of the event. We compare macroscopic features, such as flow outline and snow deposition of the simulated avalanche to field observations. An in-depth analysis of transient 3-D flow structures at the avalanche head not only demonstrates the degree of physical detail in the model, but also highlights challenges which still need to be addressed.

Publications 1 - 10 of 15

Journal: Annals of Glaciology

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