Recent and future warm extreme events and high-mountain slope stability

The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future. Although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied, the impacts of short-term, unusually warm temperature increases on slope stability in high mountains remain largely unexplored. We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing. We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001–2050 compared with a 1951–2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5–4 times by 2050 and in some models by up to 10 times. Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw. Although these processes reduce slope strength, they must be considered within the local geological, glaciological and topographic context of a slope.

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The future of ski resorts in the Swiss Alps: using DMDU to identify tipping points

10.5194/egusphere-egu21-12302 ◽

2021 ◽

Author(s):

Saeid Ashraf Vaghefi ◽

Veruska Muccione ◽

Kees C.H. van Ginkel ◽

Marjolijn Haasnoot

Keyword(s):

Snow Cover ◽

Climate Models ◽

Swiss Alps ◽

Tipping Points ◽

Annual Variability ◽

Ski Resorts ◽

The Future ◽

Total Profit ◽

Climate Uncertainty ◽

Snow Conditions

The future of ski resorts in the Swiss Alps is highly uncertain. Being dependent on snow cover conditions, winter sport tourism is highly susceptible to changes in temperature and precipitation. With the observed warming of the European Alps being well above global average warming, snow cover in Switzerland is projected to shrink at a rapid pace. Climate uncertainty originates from greenhouse gas emission trajectories (RCPs) and differences between climate models. Beyond climate uncertainty, the snow conditions are strongly subject to intra-annual variability. Series of unfavorable years have already led to the financial collapse of several low-altitude ski resorts. Such abrupt collapses with a large impact on the regional economy can be referred to as climate change induced socio-economic tipping points. To some degree, tipping points may be avoided by adaptation measures such as artificial snowmaking, although these measures are also subject to physical and economical constraints. In this study, we use a variety of exploratory modeling techniques to identify tipping points in a coupled physical-economic model applied to six representative ski resorts in the Swiss Alps. New high-resolution climate projections (CH2018) are used to represent climate uncertainty. To improve the coverage of the uncertainty space and accounting for the intra-annual variability of the climate models, a resampling technique was used to produce new climate realizations. A snow process model is used to simulate daily snow-cover in each of the ski resorts. The likelihood of survival of each resort is evaluated from the number of days with good snow conditions for skiing compared to the minimum thresholds obtained from the literature. Economically, the good snow days are translated into the total profit of ski resorts per season of operation. Multiple unfavorable years of total profit may lead to a tipping point. We use scenario discovery to identify the conditions under which these tipping points occur, and reflect on their implications for the future of snow tourism in the Swiss Alps.

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Semi-automated calibration method for modelling of mountain permafrost evolution in Switzerland

The Cryosphere ◽

10.5194/tc-10-2693-2016 ◽

2016 ◽

Vol 10 (6) ◽

pp. 2693-2719 ◽

Cited By ~ 10

Author(s):

Antoine Marmy ◽

Jan Rajczak ◽

Reynald Delaloye ◽

Christin Hilbich ◽

Martin Hoelzle ◽

...

Keyword(s):

Large Scale ◽

Calibration Method ◽

Swiss Alps ◽

Climate Projections ◽

European Alps ◽

Permafrost Degradation ◽

Future Evolution ◽

Mountainous Regions ◽

Automated Calibration ◽

The Future

Abstract. Permafrost is a widespread phenomenon in mountainous regions of the world such as the European Alps. Many important topics such as the future evolution of permafrost related to climate change and the detection of permafrost related to potential natural hazards sites are of major concern to our society. Numerical permafrost models are the only tools which allow for the projection of the future evolution of permafrost. Due to the complexity of the processes involved and the heterogeneity of Alpine terrain, models must be carefully calibrated, and results should be compared with observations at the site (borehole) scale. However, for large-scale applications, a site-specific model calibration for a multitude of grid points would be very time-consuming. To tackle this issue, this study presents a semi-automated calibration method using the Generalized Likelihood Uncertainty Estimation (GLUE) as implemented in a 1-D soil model (CoupModel) and applies it to six permafrost sites in the Swiss Alps. We show that this semi-automated calibration method is able to accurately reproduce the main thermal condition characteristics with some limitations at sites with unique conditions such as 3-D air or water circulation, which have to be calibrated manually. The calibration obtained was used for global and regional climate model (GCM/RCM)-based long-term climate projections under the A1B climate scenario (EU-ENSEMBLES project) specifically downscaled at each borehole site. The projection shows general permafrost degradation with thawing at 10 m, even partially reaching 20 m depth by the end of the century, but with different timing among the sites and with partly considerable uncertainties due to the spread of the applied climatic forcing.

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Schistidium foraminis-martini sp. nov. (Grimmiaceae), a high mountain calcicole from the European Alps molecularly related to S. agassizii

Bryophyte Diversity and Evolution ◽

10.11646/bde.44.1.1 ◽

2021 ◽

Vol 44 (1) ◽

Author(s):

THOMAS KIEBACHER ◽

HERIBERT KÖCKINGER ◽

HANS H. BLOM

Keyword(s):

New Species ◽

Its Region ◽

Swiss Alps ◽

High Mountain ◽

European Alps ◽

A New Species

Schistidium foraminis-martini is described as a new species from the Austrian and Swiss Alps. The taxon is characterized by a warm brown coloration, ovate, concave and muticous leaves with rounded apices, ellipsoid capsules, constricted at mouth, the presence of stomata and a reduced, truncate peristome. Based on sequences of the ITS region the new species is phylogenetically rather isolated, exhibiting the closest relationship to S. agassizii which shares the muticous leaves but differs in having narrowly lingulate-lanceolate, almost flat leaves, cyathiform capsules and a perfect peristome. Schistidium foraminis-martini grows on moist calcareous rocks in the alpine and nival belt.

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On the influence of topographic, geological and cryospheric factors on rock avalanches and rockfalls in high-mountain areas

Natural Hazards and Earth System Science ◽

10.5194/nhess-12-241-2012 ◽

2012 ◽

Vol 12 (1) ◽

pp. 241-254 ◽

Cited By ~ 78

Author(s):

L. Fischer ◽

R. S. Purves ◽

C. Huggel ◽

J. Noetzli ◽

W. Haeberli

Keyword(s):

Slope Failure ◽

Temporal Distribution ◽

High Mountain ◽

European Alps ◽

Permafrost Degradation ◽

Slope Failures ◽

Mountain Areas ◽

Investigation Area ◽

Rock Avalanches ◽

Slope Instabilities

Abstract. The ongoing debate about the effects of changes in the high-mountain cryosphere on rockfalls and rock avalanches suggests a need for more knowledge about characteristics and distribution of recent rock-slope instabilities. This paper investigates 56 sites with slope failures between 1900 and 2007 in the central European Alps with respect to their geological and topographical settings and zones of possible permafrost degradation and glacial recession. Analyses of the temporal distribution show an increase in frequency within the last decades. A large proportion of the slope failures (60%) originated from a relatively small area above 3000 m a.s.l. (i.e. 10% of the entire investigation area). This increased proportion of detachment zones above 3000 m a.s.l. is postulated to be a result of a combination of factors, namely a larger proportion of high slope angles, high periglacial weathering due to recent glacier retreat (almost half of the slope failures having occurred in areas with recent deglaciation), and widespread permafrost occurrence. The lithological setting appears to influence volume rather than frequency of a slope failure. However, our analyses show that not only the changes in cryosphere, but also other factors which remain constant over long periods play an important role in slope failures.

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Distributed glacier mass-balance modelling as an important component of modern multi-level glacier monitoring

Annals of Glaciology ◽

10.3189/172756406781812285 ◽

2006 ◽

Vol 43 ◽

pp. 335-343 ◽

Cited By ~ 63

Author(s):

Horst Machguth ◽

Frank Paul ◽

Martin Hoelzle ◽

Wilfried Haeberli

Keyword(s):

Energy Balance ◽

Mass Balance ◽

Climate Models ◽

Numerical Models ◽

Field Measurements ◽

Length Change ◽

Swiss Alps ◽

High Mountain ◽

Glacier Mass Balance ◽

Spatio Temporal

AbstractModern concepts of worldwide glacier monitoring include numerical models for (1) interconnecting the different levels of observations (local mass balance, representative length change, glacier inventories for global coverage) and (2) extrapolations in space (coupling with climate models) and time (backward and forward). In this context, one important new tool is distributed mass-balance modelling in complex mountain topography. This approach builds on simplified energy-balance models and can be applied for investigating the spatio-temporal representativity of the few mass-balance measurements, for estimating balance values at the tongue of unmeasured glaciers in order to derive long-term average balance values from a great number of glaciers with known length change, and for assessing special effects such as the influence of Sahara dust falls on the albedo and mass balance or autocorrelation effects due to surface darkening of glaciers with strongly negative balances. Experience from first model runs in the Swiss Alps and from applications to the extreme conditions in summer 2003 provides evidence about the usefulness of this approach for glacier monitoring and analysis of glacier changes in high-mountain regions. The main difficulties concern the spatial variability of the input parameters (e.g. precipitation, snow cover and surface albedo) and the uncertainties in the parameterizations of the components of the energy balance. Field measurements remain essential to tie the models to real ground conditions.

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Semi-automated calibration method for modelling of mountain permafrost evolution in Switzerland

The Cryosphere Discussions ◽

10.5194/tcd-9-4787-2015 ◽

2015 ◽

Vol 9 (5) ◽

pp. 4787-4843 ◽

Cited By ~ 2

Author(s):

A. Marmy ◽

J. Rajczak ◽

R. Delaloye ◽

C. Hilbich ◽

M. Hoelzle ◽

...

Keyword(s):

Climate Change ◽

Calibration Method ◽

Swiss Alps ◽

European Alps ◽

Permafrost Degradation ◽

Future Evolution ◽

Automated Calibration ◽

Mountain Permafrost ◽

The Future

Abstract. Permafrost is a widespread phenomenon in the European Alps. Many important topics such as the future evolution of permafrost related to climate change and the detection of permafrost related to potential natural hazards sites are of major concern to our society. Numerical permafrost models are the only tools which facilitate the projection of the future evolution of permafrost. Due to the complexity of the processes involved and the heterogeneity of Alpine terrain, models must be carefully calibrated and results should be compared with observations at the site (borehole) scale. However, a large number of local point data are necessary to obtain a broad overview of the thermal evolution of mountain permafrost over a larger area, such as the Swiss Alps, and the site-specific model calibration of each point would be time-consuming. To face this issue, this paper presents a semi-automated calibration method using the Generalized Likelihood Uncertainty Estimation (GLUE) as implemented in a 1-D soil model (CoupModel) and applies it to six permafrost sites in the Swiss Alps prior to long-term permafrost evolution simulations. We show that this automated calibration method is able to accurately reproduce the main thermal condition characteristics with some limitations at sites with unique conditions such as 3-D air or water circulation, which have to be calibrated manually. The calibration obtained was used for RCM-based long-term simulations under the A1B climate scenario specifically downscaled at each borehole site. The projection shows general permafrost degradation with thawing at 10 m, even partially reaching 20 m depths until the end of the century, but with different timing among the sites. The degradation is more rapid at bedrock sites whereas ice-rich sites with a blocky surface cover showed a reduced sensitivity to climate change. The snow cover duration is expected to be reduced drastically (between −20 to −37 %) impacting the ground thermal regime. However, the uncertainty range of permafrost projections is large, resulting mainly from the broad range of input climate data from the different GCM-RCM chains of the ENSEMBLES data set.

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Observed change of the standardized precipitation index, its potential cause and implications to future climate change in the Amazon region

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2007.0022 ◽

2008 ◽

Vol 363 (1498) ◽

pp. 1767-1772 ◽

Cited By ~ 95

Author(s):

Wenhong Li ◽

Rong Fu ◽

Robinson I. Negrón Juárez ◽

Katia Fernandes

Keyword(s):

Climate Change ◽

Climate Models ◽

Standardized Precipitation Index ◽

Amazon Region ◽

Precipitation Index ◽

Future Climate Change ◽

Anthropogenic Factors ◽

Internal Climate Variability ◽

Recent Climate ◽

The Future

Observations show that the standard precipitation index (SPI) over the southern Amazon region decreased in the period of 1970–1999 by 0.32 per decade, indicating an increase in dry conditions. Simulations of constant pre-industrial climate with recent climate models indicate a low probability ( p =0%) that the trends are due to internal climate variability. When the 23 models are forced with either anthropogenic factors or both anthropogenic and external natural factors, approximately 13% of sampled 30-year SPI trends from the models are found to be within the range of the observed SPI trend at 95% confidence level. This suggests a possibility of anthropogenic and external forcing of climate change in the southern Amazon. On average, the models project no changes in the frequency of occurrence of low SPI values in the future; however, those models which produce more realistic SPI climatology, variability and trend over the period 1970–1999 show more of a tendency towards more negative values of SPI in the future. The analysis presented here suggests a potential anthropogenic influence on Amazon drying, which warrants future, more in-depth, study.

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Glacier Ice Thickness Estimation and Future Lake Formation in Swiss Southwestern Alps—The Upper Rhône Catchment: A VOLTA Application

Remote Sensing ◽

10.3390/rs12203443 ◽

2020 ◽

Vol 12 (20) ◽

pp. 3443 ◽

Cited By ~ 1

Author(s):

Saeideh Gharehchahi ◽

William H. M. James ◽

Anshuman Bhardwaj ◽

Jennifer L. R. Jensen ◽

Lydia Sam ◽

...

Keyword(s):

Swiss Alps ◽

Population Increase ◽

Glacial Lake ◽

Ice Thickness ◽

High Mountain ◽

Bed Topography ◽

Lake Formation ◽

Morphological Criteria ◽

The Future ◽

Glacier Ice

Glacial lake formations are currently being observed in the majority of glacierized mountains in the world. Given the ongoing climate change and population increase, studying glacier ice thickness and bed topography is a necessity for understanding the erosive power of glacier activity in the past and lake formation in the future. This study uses the available information to predict potential sites for future lake formation in the Upper Rhône catchment located in the Southwestern Swiss Alps. The study integrates the latest available glacier outlines and high-quality digital elevation models (DEMs) into the Volume and Topography Automation (VOLTA) model to estimate ice thickness within the extent of the glaciers. Unlike the previous ice thickness models, VOLTA calculates ice thickness distribution based on automatically-derived centerlines, while optimizing the model by including the valley side drag parameter in the force equation. In this study, a total ice volume of 37.17 ± 12.26 km3 (1σ) was estimated for the Upper Rhône catchment. The comparison of VOLTA performance indicates a stronger relationship between measured and predicted bedrock, confirming the less variability in VOLTA’s results (r2 ≈ 0.92) than Glacier Bed Topography (GlabTop) (r2 ≈ 0.82). Overall, the mean percentage of ice thickness error for all measured profiles in the Upper Rhône catchment is around ±22%, of which 28 out of 42 glaciers are underestimated. By incorporating the vertical accuracy of free-ice DEM, we could identify 171 overdeepenings. Among them, 100 sites have a high potential for future lake formation based on four morphological criteria. The visual evaluation of deglaciated areas also supports the robustness of the presented methodology, as 11 water bodies were already formed within the predicted overdeepenings. In the wake of changing global climate, such results highlight the importance of combined datasets and parameters for projecting the future glacial landscapes. The timely information on future glacial lake formation can equip planners with essential knowledge, not only for managing water resources and hazards, but also for understanding glacier dynamics, catchment ecology, and landscape evolution of high-mountain regions.

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Prospecting alpine permafrost with Spectral Induced Polarization in different geomorphological landforms

10.5194/egusphere-egu2020-10131 ◽

2020 ◽

Author(s):

Theresa Maierhofer ◽

Timea Katona ◽

Christin Hilbich ◽

Christian Hauck ◽

Adrian Flores-Orozco

Keyword(s):

Electrical Resistivity ◽

Thermal State ◽

Geophysical Methods ◽

Induced Polarization ◽

Swiss Alps ◽

High Mountain ◽

Monitoring Site ◽

European Alps ◽

Mountain Permafrost

Permafrost regions are highly sensitive to climate changes, which has significant implications for the hydrological regimes and the mechanical state of the subsurface leading to natural hazards such as rock slope failures. Therefore, a better understanding of the future evolution and dynamics of mountain permafrost is highly relevant and monitoring of the thermal state of permafrost has become an essential task in the European Alps. Geophysical methods have emerged as well-suited to support borehole data and investigate the spatial distribution and temporal changes of temperature and the degradation of permafrost. In particular, electrical resistivity tomography (ERT) has developed into a routine imaging tool for the quantification of ice-rich permafrost, commonly associated with a significant increase in the electrical resistivity. However, in many cases, the interpretation of the subsurface electrical resistivity is ambiguous and additional information would improve the quantification of the ice content within the subsurface. Theoretical and laboratory studies have suggested that ice exhibits a characteristic induced electrical polarization response. Our results from an extensive field programme including many morphologically different mountain permafrost sites now indicate that this IP response may indeed be detected in the field suggesting the potential of the Induced Polarization (IP) method to overcome such ambiguities. We present here Spectral IP (SIP) mapping results conducted over a broad range of frequencies (0.1-225 Hz) at four representative permafrost sites of the Swiss-, Italian- and Austrian Alps. The mapping results have been used to install long-term permafrost monitoring arrays for a better understanding of subsurface variations associated to climate change. All SIP study sites are located at elevations around 2600 - 3000 m and include comprehensive geophysical and temperature data for validation. We focus on the spatial characterization of each site to address different research questions: to (i) reproduce and improve the mapping of the spatial permafrost extent inferred from previous investigations in the Lapires talus slope,Western Swiss Alps, to (ii) improve the geophysical characterization of the Sonnblick monitoring site located in the Austrian Central Alps, to (iii) determine the transition between permafrost and non-permafrost at the Schilthorn site, Bernese Alps, Switzerland, and to (iv) find the best-suited location for a SIP monitoring profile and conduct year-round measurements at the Cime Bianche site, Western Italian Alps. Our various field applications demonstrate the potential of the IP method for characterizing and monitoring permafrost systems in high-mountain environments.

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Does climate change influence the frequency of large rock slope failures?

10.5194/egusphere-egu2020-7361 ◽

2020 ◽

Author(s):

Simon Loew ◽

Nora Buehler ◽

Jordan Aaron

Keyword(s):

Slope Failure ◽

Rock Slope ◽

Negative Temperature ◽

Climatic Conditions ◽

Swiss Alps ◽

Rock Fall ◽

Mean Annual Temperature ◽

European Alps ◽

Depth Range ◽

Slope Failures

A large number of scientific contributions (e.g. BAFU 2017, Speicher 2017, Phillips et al. 2017, Ravanel et al. 2017, Haque et al. 2016) have suggested that many recent rock slope failures in the European Alps have been triggered by climate warming. For example, Huggel et al. 2012 and Fischer et al. 2012 could show that rock fall frequencies above 2000 masl increased significantly since 1990 at regional (Swiss Alps and adjacent areas) and local (Mont Blanc) scale, based on 52 events larger than 1000 m3 (PERMOS data base) covering the period 1900-2010. This increase in frequency could be correlated with a significant departure of mean annual temperature from the 1960&#8211;1990 average, based on a dataset describing conditions in Switzerland. Paranunzio et al. 2016 systematically studied the climatic conditions and anomalies occurring before 41 rock fall events in the Italian Alps with volumes of several hundred to several million m3. They show that positive and negative temperature anomalies triggered the majority of analysed rock fall events in a complex manner, but that melting of permafrost was clearly not the only rock fall trigger.However, there have been no studies which systematically investigate changes in the frequency of rock fall events based on complete inventories covering a large range of rock fall volumes. To fill this gap, we have generated a new database for rapid rock slope failures in the Swiss Alps covering events larger than 100&#8217;000 m3 (B&#252;hler 2019, BSc Thesis ETH 2019). This catalogue covers the period between 1700 and 2019 and includes 86 events with reliably estimated volume, date and location of occurrence, and pre-disposing factors (such as slope orientation, permafrost occurrence and geological setting). Volume-cumulative frequency plots of the events demonstrate completeness of the catalogue for all size classes, and significant changes in the ratios between large and small events through time.An enhanced frequency of the volume class of 105 m3 (100&#8217;000-999&#8217;000 m3) is observed starting from 1940, predominantly occurring in permafrost areas and elevations ranging between 2800 and 3200 masl. This increasing frequency signal with time disappears for increasing volumes beyond a magnitude of about 400&#8217;000 m3 and is clearly absent for very large rock slope failure of millions to tens of millions of m3.The volume dependence of climate sensitivity can be physically explained, as larger volume slope failures tend to have deeper failure surfaces. Typical failure depth for multi-million m3 slope failures in crystalline rocks are up to a few 100 meters, and beyond the depth of Alpine permafrost. Direct impacts of surface temperature changes on permafrost are mainly manifested through a minor thickening of the active layer, typically ranging between 1 and 10 meters, but indirect effects at the depth range of decameters (i.e. the depth of failure surfaces for events of the 105 m3 class) have been assessed and demonstrated in a large number of studies.

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