Swiss Glaciers Research Articles

As Existing Cities Adapt to Climate Change, Can Dynamic Systems Analysis Be Useful in Building a Sustainable Future?

Abstract The World Meteorological Organization estimates that Swiss glaciers lost 6% of their volume in 2022 (Niiler, 2023, “Europe’s Glaciers Melted at Record Rate,” Wall Street J). For summer tourism, this happens to be good news. This means a busier and longer season, more biking and hiking tours and more income for tour operators. However, there are steeper costs that come with such localized benefits of climate change; smaller glaciers also mean less water for drinking, less water for the crops, and less hydroelectricity for the population at-large. This paper outlines how cities and urban areas may moderate the effects of climate change, adapt coping strategies and assure a sustainable future for local populations and the region’s economy by analyzing the cross-correlation, magnitude, and time-dependence of the “causes” and the “effects.” After investigating other mathematical models addressing the effects of climate change (Fernandez et al., 2017, “A 3D Optimal Control Problem Related to the Urban Heat Islands,” J. Math. Anal. Appl., 446(2), pp. 1571–1605; Eikenberry and Gumel, 2018, “Mathematical Modeling of Climate Change and Malaria Transmission Dynamics: A Historical Review,” J. Math. Biol., 77(4), pp. 857–933; Mordecai et al., 2013, “Optimal Temperature for Malaria Transmission is Dramatically Lower Than Previously Predicted,” Ecol. Lett., 16(1), pp. 22–30), this paper proposes a dynamic systems and controls approach to urban development and planning. Climate-related risks such as a rise in temperature that diminishes the ability of typically low-skilled workers to work outside or coastal flooding that shrinks a city’s housing stock and pushes poorer populations to homelessness, crime, and drug abuse are interconnected as in a dynamic system that changes with time in scale and need to be analyzed accordingly (see Fig.1). The author also proposes creating “digital twins” of critical infrastructure, which can be done at comparatively lower cost, in order to analyze if the “inputs” including the remedial measures proposed, will yield the desired “outputs” and run iterations as needed until stable solutions are found.

The Decaying Near‐Surface Boundary Layer of a Retreating Alpine Glacier

AbstractThe presence of a developed boundary layer decouples a glacier's response from ambient conditions, suggesting that sensitivity to climate change is increased by glacier retreat. To test this hypothesis, we explore six years of distributed meteorological data on a small Swiss glacier in the period 2001–2022. Large glacier fragmentation has occurred since 2001 (−35% area change up to 2022) coinciding with notable frontal retreat, an observed switch from down‐glacier katabatic to up‐glacier valley winds and an increased sensitivity (ratio) of on‐glacier to off‐glacier temperature. As the glacier ceases to develop density‐driven katabatic winds, sensible heat fluxes on the glacier are increasingly determined by the conditions occurring outside the boundary layer of the glacier, sealing the glacier's demise as the climate continues to warm and experience an increased frequency of extreme summers.

Halving of Swiss glacier volume since 1931 observed from terrestrial image photogrammetry

Abstract. The monitoring of glaciers in Switzerland has a long tradition, yet glacier changes during the 20th century are only known through sparse observations. Here, we estimate a halving of Swiss glacier volumes between 1931 and 2016 by mapping historical glacier elevation changes at high resolution. Our analysis relies on a terrestrial image archive known as TerrA, which covers about 86 % of the Swiss glacierised area with 21 703 images acquired during the period 1916–1947 (with a median date of 1931). We developed a semi-automated workflow to generate digital elevation models (DEMs) from these images, resulting in a 45 % total glacier coverage. Using the geodetic method, we estimate a Swiss-wide glacier mass balance of −0.52 ± 0.09 m w.e. a−1 between 1931 and 2016. This equates to a 51.5 ± 8.0 % loss in glacier volume. We find that low-elevation, high-debris-cover, and gently sloping glacier termini are conducive to particularly high mass losses. In addition to these glacier-specific, quasi-centennial elevation changes, we present a new inventory of glacier outlines with known timestamps and complete attributes from around 1931. The fragmented spatial coverage and temporal heterogeneity of the TerrA archive are the largest sources of uncertainty in our glacier-specific estimates, reaching up to 0.50 m w.e. a−1. We suggest that the high-resolution mapping of historical surface elevations could also unlock great potential for research fields other than glaciology.

Rescue and homogenization of 140 years of glacier mass balance data in Switzerland

Abstract. Glacier monitoring in Switzerland has resulted in some of the longest and most complete data series globally. Mass balance observations at individual locations, starting in the 19th century, are the backbone of the monitoring as they represent the raw and original glaciological data demonstrating the response of snow accumulation and snow/ice melt to changes in climate forcing. So far, however, the variety of sources of historic measurements has not been systematically processed and documented. Here, we present a new complete and extensive point glacier mass balance dataset for the Swiss Alps that provides attributes for data quality and corresponding uncertainties. Original sources were digitized or re-assessed to validate or to correct existing entries and to identify metadata. The sources of data are highly diverse and stem from almost 140 years of records, originating from handwritten field notes, unpublished project documents, various digital sources, published reports, and meta-knowledge of the observers. The project resulted in data series with metadata for 63 individual Swiss glaciers, including more than 60 000 point observations of mass balance. Data were systematically analysed and homogenized, e.g. by supplementing partly missing information based on correlations inferred from direct measurements. A system to estimate uncertainty in all individual observations was developed indicating that annual point balance is measured with a typical error of 0.07 m water equivalent (w.e.), while the average error in winter snow measurements is 0.20 m w.e. Our dataset permits further investigating the climate change impacts on Swiss glaciers. Results show an absence of long-term trends in snow accumulation over glaciers while melt rates have substantially increased over the last 3 decades. The complete dataset is available at DOI https://doi.org/10.18750/massbalance.point.2021.r2021 (GLAMOS, 2021).

Brief communication: Application of a muonic cosmic ray snow gauge to monitor the snow water equivalent on alpine glaciers

Abstract. Monitoring the snow water equivalent (SWE) in the harsh environments of high mountain regions is a challenge. Here, we explore the use of muon counts to infer SWE. We deployed a muonic cosmic ray snow gauge (μ-CRSG) on a Swiss glacier during the snow-rich winter season 2020/21 (almost 2000 mm w.e.). The μ-CRSG measurements agree well with measurements by a neutronic cosmic ray snow gauge (n-CRSG), and they lie within the uncertainty of manual observations. We conclude that the μ-CRSG is a highly promising method to monitor SWE in remote high mountain environments with several advantages over the n-CRSG.

Subglacial Channels, Climate Warming, and Increasing Frequency of Alpine Glacier Snout Collapse

AbstractAlpine glacier retreat has increased markedly since the late 1980s and is commonly linked to the effects of rising temperature on the surface melt. Less considered are processes associated with glacier snout‐marginal surface collapse. A survey of 22 retreating Swiss glaciers suggests that collapse events have increased in frequency since the early 2000s, driven by ice thinning and reductions in glacier‐longitudinal ice flux. Detailed measurement of a collapse event at one glacier showed 0.02 m/day vertical surface deformation above a meandering main subglacial channel. However, with low rates of longitudinal flux (<1.3 m/year), this was insufficient to close the channel in the snout marginal zone. We hypothesize that an open channel maintains contact between subglacial ice and the atmosphere, allowing greater incursion of warm air up‐glacier, thus enhancing melt from below. The associated meandering of subglacial channels at glacier snouts leads to surface collapse and removal of ice via fluvial processes.

Assimilating near-real-time mass balance stake readings into a model ensemble using a particle filter

Abstract. Short-term glacier variations can be important for water supplies or hydropower production, and glaciers are important indicators of climate change. This is why the interest in near-real-time mass balance nowcasting is considerable. Here, we address this interest and provide an evaluation of continuous observations of point mass balance based on online cameras transmitting images every 20 min. The cameras were installed on three Swiss glaciers during summer 2019, provided 352 near-real-time point mass balances in total, and revealed melt rates of up to 0.12 m water equivalent per day (mw.e.d-1) and of more than 5 mw.e. in 81 d. By means of a particle filter, these observations are assimilated into an ensemble of three TI (temperature index) and one simplified energy-balance mass balance models. State augmentation with model parameters is used to assign temporally varying weights to individual models. We analyze model performance over the observation period and find that the probability for a given model to be preferred by our procedure is 39 % for an enhanced TI model, 24 % for a simple TI model, 23 %, for a simplified energy balance model, and 14 % for a model employing both air temperature and potential solar irradiation. When compared to reference forecasts produced with both mean model parameters and parameters tuned on single mass balance observations, the particle filter performs about equally well on the daily scale but outperforms predictions of cumulative mass balance by 95 %–96 %. A leave-one-out cross-validation on the individual glaciers shows that the particle filter is also able to reproduce point observations at locations not used for model calibration. Indeed, the predicted mass balances is always within 9 % of the observations. A comparison with glacier-wide annual mass balances involving additional measurements distributed over the entire glacier mostly shows very good agreement, with deviations of 0.02, 0.07, and 0.24 mw.e.

The New Swiss Glacier Inventory SGI2016: From a Topographical to a Glaciological Dataset

Glaciers in Switzerland are shrinking rapidly in response to ongoing climate change. Repeated glacier inventories are key to monitor such changes at the regional scale. Here we present the new Swiss Glacier Inventory 2016 (SGI2016) that has been acquired based on sub-meter resolution aerial imagery and digital elevation models, bringing together topographical and glaciological approaches and knowledge. We define the process, workflow and required glaciological adaptations to compile a highly detailed inventory based on the digital Swiss Topographic Landscape model. The SGI2016 provides glacier outlines (areas), supraglacial debris cover and ice divides for all Swiss glaciers referring to the years 2013–2018. The SGI2016 maps 1,400 individual glacier entities with a total surface area of 961 ± 22 km2, whereof 11% (104 km2) are debris-covered. It constitutes the so far most detailed cartographic representation of glacier extent in Switzerland. Interpretation in the context of topographic parameters indicates that glaciers with moderate inclination and low median elevation tend to have highest fractions of supraglacial debris. Glacier-specific area changes since 1973 show the largest relative changes for small and low-elevation glaciers. The analysis further indicates a tendency for glaciers with a high share of supraglacial debris to show larger relative area changes. Between 1973 and 2016, an area change rate of –0.6% a−1 is found. Based on operational data sets and the presented methodology, the Swiss Glacier Inventory will be updated in 6-yr time intervals, leading to a high consistency in future glacier change assessments.

Continuous Spatio-Temporal High-Resolution Estimates of SWE Across the Swiss Alps – A Statistical Two-Step Approach for High-Mountain Topography

Snow and precipitation estimates in high-mountain regions typically suffer from low temporal and spatial resolution and large uncertainties. Here, we present a two-step statistically based model to derive spatio-temporal highly resolved estimates of snow water equivalent (SWE) across the Swiss Alps. A multiple linear regression model (Step-1 MLR) was first used to combine the CombiPrecip radar-gauge product with the precipitation and wind speed (10 m from the ground) of the numerical weather prediction model COSMO-1 in order to adjust the precipitation estimates. Step-1 MLR was trained with SWE data from a cosmic ray sensor (CRS) installed on the Plaine Morte glacier and tested with SWE data from a CRS on the Findel glacier. Step-1 MLR was then applied to the entire area of eight Swiss glaciers and evaluated with scattered end-of-season in-situ manual SWE measurements. The cumulative estimates of Step-1 MLR were found to agree well with the end-of-season measurements. The observed differences can partially be explained by considering the radar visibility, melting processes and preferential snow deposition, which are dictated by the local topography and local weather conditions. To address these limitations of Step-1 MLR, several high-resolution topographical parameters and a solar radiation parameter were included in the subsequent MLR version (Step-2 MLR). Step-2 MLR was evaluated by means of cross-validation, and it showed an overall correlation of 0.78 and a mean bias error of 4 mm with respect to end-of-season in-situ measurements. Step-2 MLR was also evaluated for non-glacierized regions by evaluating it against twice-monthly manual SWE measurements at 44 sites in the Swiss Alps. In such a setting, the Step-2 model showed an overall weaker correlation (0.53) and a higher mean bias error (31 mm). On the other hand, negative variations of the measured SWE were removed because of the lower altitude of the sites, thereby leading to more pronounced melting periods, which again increased the correlation values to 0.63 and reduced the mean bias error to 12 mm. Such results confirm the high potential of the model for applications to other mountainous regions.

Ice thickness distribution of all Swiss glaciers based on extended ground-penetrating radar data and glaciological modeling

AbstractAccurate knowledge of the ice thickness distribution and glacier bed topography is essential for predicting dynamic glacier changes and the future developments of downstream hydrology, which are impacting the energy sector, tourism industry and natural hazard management. Using AIR-ETH, a new helicopter-borne ground-penetrating radar (GPR) platform, we measured the ice thickness of all large and most medium-sized glaciers in the Swiss Alps during the years 2016–20. Most of these had either never or only partially been surveyed before. With this new dataset, 251 glaciers – making up 81% of the glacierized area – are now covered by GPR surveys. For obtaining a comprehensive estimate of the overall glacier ice volume, ice thickness distribution and glacier bed topography, we combined this large amount of data with two independent modeling algorithms. This resulted in new maps of the glacier bed topography with unprecedented accuracy. The total glacier volume in the Swiss Alps was determined to be 58.7 ± 2.5 km3 in the year 2016. By projecting these results based on mass-balance data, we estimated a total ice volume of 52.9 ± 2.7 km3 for the year 2020. Data and modeling results are accessible in the form of the SwissGlacierThickness-R2020 data package.

Multi-sensor analysis of monthly gridded snow precipitation on alpine glaciers

Abstract. Accurate and reliable solid precipitation estimates for high mountain regions are crucial for many research applications. Yet, measuring snowfall at high elevation remains a major challenge. In consequence, observational coverage is typically sparse, and the validation of spatially distributed precipitation products is complicated. This study presents a novel approach using reliable daily snow water equivalent (SWE) estimates by a cosmic ray sensor on two Swiss glacier sites to assess the performance of various gridded precipitation products. The ground observations are available during two and four winter seasons. The performance of three readily-available precipitation data products based on different data sources (gauge-based, remotely-sensed, and re-analysed) is assessed in terms of their accuracy compared to the ground reference. Furthermore, we include a data set, which corresponds to the remotely-sensed product with a local adjustment to independent SWE measurements. We find a large bias of all precipitation products at a monthly and seasonal resolution, which also shows a seasonal trend. Moreover, the performance of the precipitation products largely depends on in situ wind direction during snowfall events. The varying performance of the three precipitation products can be partly explained with their compilation background and underlying data basis.

Quantifying the overall effect of artificial glacier melt reduction in Switzerland, 2005–2019

The artificial reduction of glacier melt is gaining increased attention due to accelerated ice wastage with atmospheric warming. In Switzerland, active coverage of glaciers using geotextiles is performed at currently nine sites and since up to 15 years. The measures represent an efficient method to locally safeguard the operability of ski slopes or other touristic attractions. Here, we present an assessment of the evolution of geotextile-covered areas and the correspondingly avoided ice melt across the Swiss Alps. Presently, about 0.18 km2, or 0.02% of the total Swiss glacier area, is covered by geotextiles, with a doubling of the covered area since 2012. Up to 350,000 m3 of ice melt per year have been mitigated by this technique. We estimate the overall costs of active glacier melt reduction, and compute the price of 1 m3 of saved glacier ice, a number relevant for planning such measures. Average costs over the last decade range from 0.6 to 7.9 CHF m−3 yr−1 depending on the type of installation and its location on the glacier. These relatively high costs are an indication for the considerable economic value attributed to glacier ice. We also show that artificial melt reduction is not scalable. Whilst local interventions can be efficient and profitable, a hypothetical application to the larger scale shows that saving Alpine glaciers by technological solutions is neither achievable nor affordable.

Can Weather Radars Be Used to Estimate Snow Accumulation on Alpine Glaciers? An Evaluation Based on Glaciological Surveys

AbstractThe snow water equivalent (SWE) is a key component for understanding changes in the cryosphere in high mountain regions. Yet, a reliable quantification at a high spatiotemporal resolution remains challenging in such environments. In this study, we investigate the potential of an operational weather radar–rain gauge composite (CombiPrecip) to infer the daily evolution of SWE on seven Swiss glaciers. To this end, we validate cumulative CombiPrecip estimates with glacier-wide manual SWE observations (snow probing, snow pits) obtained around the time of the seasonal peak during four winter seasons (2015–19). CombiPrecip underestimates the end-of-season snow accumulation by factors of 2.2 up to 3.7, depending on the glacier site. These factors are consistent over the four winter seasons. The regional variability can be mainly attributed to the empirical visibility of the Swiss radar network within the Alps. To account for the underestimation, we investigate three approaches to adjust CombiPrecip for the applicability to glacier sites. Thereby, we combine the factor of underestimation with a precipitation-phase parameterization. For further comparison, we apply a rain gauge catch-efficiency function based on wind speed. We validate these approaches with 14 manual point observations of SWE obtained on two glaciers during three winter seasons. All approaches show a similar improvement of CombiPrecip estimates. We conclude that CombiPrecip has great potential to estimate SWE on glaciers at a high temporal resolution, but further investigations are necessary to understand the regional variability of the bias throughout the Swiss Alps.

Glacial overdeepenings in the Swiss Alps and foreland: Spatial distribution and morphometrics

Overdeepenings (ODs) are erosional features that have been excavated below the regional sea/fluvial base level to produce closed topographic basins. Accessing bedrock topography and OD volume is often challenging. Hence, despite constituting major landscape features and being widespread in (paleo-)glaciated regions, ODs have been overlooked and the subglacial processes involved in their evolution have remained debated. In the Swiss Alpine foreland and valleys, ODs are commonly found filled with water or large volumes of sediment. Using a GIS-Matlab approach based on topographic datasets and bedrock contour-curves, we mapped the spatial distribution of ODs in Switzerland and adjacent areas in the ice-free Alpine areas. The majority of the mapped ODs occurs in very-low bedrock erosional resistance, where ODs are larger, wider and shallower than in medium to high bedrock erosional resistance domains, evidencing a strong lithological control on OD geometry. Longitudinal asymmetry and hypsometric integral suggest a dominance of quarrying during OD evolution and, for selected glacial catchments, headward erosion propagation or high sediment evacuation efficiency. OD surface data (surface and length) can be tentatively used for extracting OD subsurface metrics (depths, nested valleys and first-order volume estimates). Our data seem to indicate that ODs may initiate as multiple small nested valleys and progress to a single and connected depression. Transversal cross-sections also suggest a negative feedback between the erosion potential for deep carving and the presence of low-resistance bedrock, where subglacial meltwater infiltration could have played a key role in OD evolution. Although insightful relationships have been evidenced for ODs in the Swiss Alps and foreland, we have also observed a high spatial variability in key OD metrics such as surface area and depth. This results in general (first-order) interpretations at regional scale, but currently prevent to quantitatively constrain physical subglacial processes at their origin. Comparisons with existing OD datasets under present-day ice (Greenland, Antarctica and modern Swiss glaciers) place our results in a broader context and allow a step forward in our understanding of the complex patterns and mechanisms of (sub-)glacial erosion and resulting landforms.

Quantity and distribution of methane entrapped in sediments of calcareous, Alpine glacier forefields

Abstract. Aside from many well-known sources, the greenhouse gas methane (CH4) was recently discovered entrapped in the sediments of Swiss Alpine glacier forefields derived from calcareous bedrock. A first study performed in one glacial catchment indicated that CH4 was ubiquitous in sediments and rocks and was largely of thermogenic origin. Here, we present the results of a follow-up study that aimed at (1) determining the occurrence and origin of sediment-entrapped CH4 in other calcareous glacier forefields across Switzerland and (2) providing an inventory of this sediment-entrapped CH4, i.e., determining the contents and total mass of CH4 present, and its spatial distribution within and between five different Swiss glacier forefields situated on calcareous formations of the Helvetic nappes in the Central Alps. Sediment and bedrock samples were collected at high spatial resolution from the forefields of Im Griess, Griessfirn, Griessen, Wildstrubel, and Tsanfleuron glaciers, representing different geographic and geologic regions of the Helvetic nappes. We performed geochemical analyses on gas extracted from sediments and rocks, including the determination of CH4 contents, stable carbon-isotope analyses (δ13CCH4), and the determination of gas-wetness ratios (ratio of CH4 to ethane and propane contents). To estimate the total mass of CH4 entrapped in glacier-forefield sediments, the total volume of sediment was determined based on the measured forefield area and either literature values of mean sediment thickness or direct depth measurements using electrical resistivity tomography. Methane was found in all sediments (0.08–73.81 µg CH4 g−1 dry weight) and most rocks (0.06–108.58 µg CH4 g−1) collected from the five glacier forefields, confirming that entrapped CH4 is ubiquitous in these calcareous formations. Geochemical analyses further confirmed a thermogenic origin of the entrapped CH4 (average δ13CCH4 of sediment of −28.23 (± 3.42) ‰; average gas-wetness ratio of 75.2 (± 48.4)). Whereas sediment-entrapped CH4 contents varied moderately within individual forefields, we noted a large, significant difference in the CH4 content and total CH4 mass (range of 200–3881 t CH4) between glacier forefields at the regional scale. The lithology and tectonic setting within the Helvetic nappes appeared to be dominant factors determining rock and sediment CH4 contents. Overall, a substantial quantity of CH4 was found to be entrapped in Swiss calcareous glacier forefields. Its potential release and subsequent fate in this environment is the subject of ongoing studies.

Detecting and characterising an englacial conduit network within a temperate Swiss glacier using active seismic, ground penetrating radar and borehole analysis

ABSTRACTEnglacial hydrology plays an important role in routing surface water to the glacier's bed and it consequently affects the glacier's dynamics. However, it is often difficult to observe englacial conduit conditions on temperate glaciers because of their short-lived nature. We acquired repeated active surface seismic data over the Rhone Glacier, Switzerland to monitor and characterise englacial conduit conditions. Amplitude-versus-angle analysis suggested that the englacial conduit is water filled and between 0.5 and 4 m thick. A grid of GPR profiles, acquired during the 2018 melt season, showed the englacial conduit network persisting and covering ~ 14,000 m2. In late summer 2018, several boreholes were drilled into the conduit network. We observed generally stable water pressure, but there were also short sudden increases. A borehole camera provided images of a fast flowing englacial stream transporting sediment through the conduit. From these observations, we infer that the englacial conduit network is fed by surface meltwater and morainal streams. The surface and morainal streams merge together, enter the glacier subglacially and flow through subglacial channels along the flank. These subglacial channels flow into highly efficient englacial conduits traversing the up-glacier section of the overdeepening before connecting with the subglacial drainage system.

Narzeczona w tafli lodu, czyli jak kino mawia o nieprzeniknioności uczuć miłosnych („45 lat” Andrew Haigha)

The subject of analysis in the article is the 2015 British film 45 Years (dir. Andrew Haigh), which is an adaptation of David Constantine’s novel In Another Country. The film presents an intimate image that, in a subtle way, talks about the complexity of feelings of love, constantly oscillate between the desire for intimate closeness and exclusiveness, and the fear of disappointment (longing for emotional fullness and a sense of failure). Inscribing the problem of the dialectical complexity of the emotional life of a man in the context of old age and transience seems unconventional and, therefore, particularly valuable in this film. An important theme in 45 Years, emphasised by the title itself, is the past; invisible on a daily basis, it lurks under the surface of the present. Its iconic (though only imaginary) representation is connected with the plot of the first, lost fiancée of the hero, whose remains – after half a century – are unexpectedly found on a Swiss glacier. The author of the article argues that the fact that it concerns a young woman’s body (preserved in a transparent substance in a strange coincidence), by virtue of intertextual implications, brings an archetypal element to the essentially prosaic story; this archetypal element has then far-reaching consequences in the symbolic plan of the film. Skilful reference to the fairy-tale motif of the ‘glass coffin’ allowed the British director for portraying in this audio-visual story, which talks about the emotional dramas of two elderly people, an image of these internal experiences that in their intimate subtlety remain impenetrable and inexpressible.

Sensitivity of mountain glacier mass balance to changes in bare-ice albedo

ABSTRACTAlbedo is an important parameter in the energy balance of bare-ice surfaces and modulates glacier melt rates. The prolongation of the ablation period enforces the albedo feedback and highlights the need for profound knowledge on impacts of bare-ice albedo on glacier mass balance. In this study, we assess the mass balance sensitivity of 12 Swiss glaciers with abundant long-term in-situ data on changes in bare-ice albedo. We use pixel-based bare-ice albedo derived from Landsat 8. A distributed mass-balance model is applied to the period 1997–2016 and experiments are performed to assess the impact of albedo changes on glacier mass balance. Our results indicate that glacier-wide mass-balance sensitivities to changes in bare-ice albedo correlate strongly with mean annual mass balances (r2= 0.81). Large alpine glaciers react more sensitively to bare-ice albedo changes due to their ablation areas being situated at lower elevations. We find average sensitivities of glacier-wide mass balance of −0.14 m w.e. a−1per 0.1 albedo decrease. Although this value is considerably smaller than sensitivity to air temperature change, we stress the importance of the enhanced albedo feedback that will be amplified due to atmospheric warming and a suspected darkening of glacier surface in the near future.

Response of a temperate alpine valley glacier to climate change at the decadal scale

Glacier advance and recession are considered key indicators of climate change. Understanding the relationship between climatic variations and glacial responses is crucial. Here, we apply archival digital photogrammetry to reconstruct the decadal scale glacial history of an unmonitored Alpine valley glacier, the Haut Glacier d'Arolla, Switzerland, and we use the data generated to explore the linkages between glacier recession and climate forcing. High precision digital elevation models were derived. They show continual recession of the glacier since 1967, associated with long‐term climatic amelioration but only a weak reaction to shorter‐term climatic deterioration. Glacier surface velocity estimates obtained using surface particle tracking showed that, unlike for most Swiss glaciers during the late 1970s and early 1980s, ice mass flux from the accumulation zone was too low to compensate for the effects of glacier thinning and subsequent snout recession, especially during the rapid warming that occurred through the 1980s. The results emphasise the dangers of inferring glacier response to climate forcing from measurements of the terminus position only and the importance of using remote sensing methods as an alternative, especially where historical imagery is available.

Surface elevation and mass changes of all Swiss glaciers 1980–2010

Abstract. Since the mid-1980s, glaciers in the European Alps have shown widespread and accelerating mass losses. This article presents glacier-specific changes in surface elevation, volume and mass balance for all glaciers in the Swiss Alps from 1980 to 2010. Together with glacier outlines from the 1973 inventory, the DHM25 Level 1 digital elevation models (DEMs) for which the source data over glacierized areas were acquired from 1961 to 1991 are compared to the swissALTI3D DEMs from 2008 to 2011 combined with the new Swiss Glacier Inventory SGI2010. Due to the significant differences in acquisition dates of the source data used, mass changes are temporally homogenized to directly compare individual glaciers or glacierized catchments. Along with an in-depth accuracy assessment, results are validated against volume changes from independent photogrammetrically derived DEMs of single glaciers. Observed volume changes are largest between 2700 and 2800 m a.s.l. and remarkable even above 3500 m a.s.l. The mean geodetic mass balance is −0.62 ± 0.07 m w.e. yr−1 for the entire Swiss Alps over the reference period 1980–2010. For the main hydrological catchments, it ranges from −0.52 to −1.07 m w.e. yr−1. The overall volume loss calculated from the DEM differencing is −22.51 ± 1.76 km3.