Search

Rockfalls are one of the most common instability processes in high mountains. They represent a relevant issue, both for the risks they represent for (infra) structures and frequentation, and for their potential role as terrestrial indicators of climate change. This study aims to contribute to the growing topic of the relationship between climate change and slope instability at the basin scale. The selected study area is the Bessanese glacial basin (Western Italian Alps) which, since 2016, has been specifically equipped, monitored and investigated for this purpose. In order to provide a broader context for the interpretation of the recent rockfall events and associated climate conditions, a cross-temporal and integrated approach has been adopted. For this purpose, geomorphological investigations (last 100 years), local climate (last 30 years) and near-surface rock/air temperatures analyses, have been carried out. First research outcomes show that rockfalls occurred in two different geomorphological positions: on rock slopes in permafrost condition, facing from NW to NE and/or along the glacier margins, on rock slopes uncovered by the ice in the last decades. Seasonal thaw of the active layer and/or glacier debutressing can be deemed responsible for slope failure preparation. With regard to timing, almost all dated rock falls occurred in summer. For the July events, initiation may have been caused by a combination of rapid snow melt and enhanced seasonal thaw of the active layer due to anomalous high temperatures, and rainfall. August events are, instead, associated with a significant positive temperature anomaly on the quarterly scale, and they can be ascribed to the rapid and/or in depth thaw of the permafrost active layer. According to our findings, we can expect that in the Bessanese glacierized basin, as in similar high mountain areas, climate change will cause an increase of slope instability in the future. To fasten knowledge deepening, we highlight the need for a growth of a network of high elevation experimental sites at the basin scale, and the definition of shared methodological and measurement standards, that would allow a more rapid and effective comparison of data.

Earth's climate is warming and will continue to warm as the century progresses. High mountains and high latitudes are experiencing the greatest warming of all regions on Earth and also are some of the most sensitive areas to climate change, in part because ecosystems and natural processes in these areas are intimately linked to the cryosphere. Evidence is mounting that warming will further reduce permafrost and snow and ice cover in high mountains, which in turn will destabilize many slopes, alter sediment delivery to streams, and change subalpine and alpine ecosystems. This paper contributes to the continuing discussion of impacts of climate change on mountain environments by comparing and discussing processes and trends in the mountains of western Canada and the European Alps. We highlight the effects of physiography and climate on physical processes occurring in the two regions. Processes of interest include landslides and debris flows induced by glacier debuttressing, alpine permafrost thaw, changes in rainfall regime, formation and sudden drainage of glacier- and moraine-dammed lakes, ice avalanches, glacier surges, and large-scale sediment transfers due to rapid deglacierization. Our analysis points out the value of integrating observations and data from different areas of the world to better understand these processes and their impacts.

Air temperature in the European Alps shows warming over recent decades at an average rate of 0.3 °C/10 years, thereby outpacing the global warming rate of 0.2 °C/10 years. The periglacial environment of the Alps is particularly important for several aspects (i.e. hydropower production, tourism, natural hazards, indicator of global warming). However, there is a lack of specific and updated studies relating to temperature change in this environment. In order to fill this gap, the recent temperature trends in the periglacial environment of the Alps were analyzed. Mean/maximum/minimum daily air temperatures recorded by 14 land-based meteorological stations were used, and the temperature indices for the period 1990–2019 were calculated. The periglacial environment of the Alps showed a warming rate of 0.4 °C/10 years, 0.6 °C/10 years and 0.8 °C/10 years for the mean/maximum/minimum temperatures, respectively. These warming rates are higher than that observed for the entire Alpine area. In 2050 many glaciers of the Alps below 3000 m altitude are expected to be extinct, and all the areas previously occupied by glaciers will become periglacial. In order to manage and adapt to these changes, more in-depth climate analyses are needed. This is necessary for all the mountainous areas of the world, which are undergoing similar changes.

For application purposes (in particular water resources management and planning) it is crucial to rely on accurate predictions of the evolution of glaciers on short time scales (from seasonal to multi-annual).This is one of the aims of the MEDSCOPE project in the framework of the ERA4CS initiative: seasonal-to-decadal climate forecasts, produced and downscaled by the project, are used to estimate the evolution of glaciers in selected areas of the Western Italian Alps.For this purpose, empirical glacier models have been calibrated with historical observational data of glacier front fluctuation and mass balance for five glaciers, characterized by different morphology and topoclimatic setting, in the Western Italian Alps. The models will be forced with the seasonal, downscaled forecasts, in order to assess the added value provided by MEDSCOPE to climate services for water management.

Glaciated and recently (post-Little Ice Age) deglaciated areas are very dynamic environments, undergoing continuous changes, in particular as a consequence of climatic fluctuations and cryosphere changes. The intense geomorphic activity that takes place here conditions natural hazard, sediment transport and tourist fruition. A geo-morphological mapping with applicative purposes has to take into account the peculiarities and the dynamism of these specific areas. We here propose a methodological approach based on the interpretation of a multitemporal set of aerial photos (from 1983 to 2012), in a GIS environment, with application to the sectors modeled by Little Ice Age glaciers in the upper Orco Valley (NW Italy). The result is a geo-morphological map focused on the elements that are most relevant for application purposes, complemented by a map of the spatio-temporal distribution of the natural instability processes identified in the study area for the reference period, aimed to highlight the recent dynamism of the geomorphological elements in the map.

Climate change is now unequivocal; however, the type and extent of terrestrial impacts are still widely debated. Among these, the effects on slope stability are receiving a growing attention in recent years, both as terrestrial indicators of climate change and implications for hazard assessment. High-elevation areas are particularly suitable for these studies, because of the presence of the cryosphere, which is particularly sensitive to climate. In this paper, we analyze 358 slope failures which occurred in the Italian Alps in the period 2000-2016, at an elevation above 1500 m a.s.l. We use a statistical-based method to detect climate anomalies associated with the occurrence of slope failures, with the aim to catch an eventual climate signal in the preparation and/or triggering of the considered case studies. We first analyze the probability values assumed by 25 climate variables on the occasion of a slope-failure occurrence. We then perform a dimensionality reduction procedure and come out with a set of four most significant and representative climate variables, in particular heavy precipitation and short-term high temperature. Our study highlights that slope failures occur in association with one or more climate anomalies in almost 92% of our case studies. One or more temperature anomalies are detected in association with most case studies, in combination or not with precipitation (47% and 38%, respectively). Summer events prevail, and an increasing role of positive temperature anomalies from spring to winter, and with elevation and failure size, emerges. While not providing a final evidence of the role of climate warming on slope instability increase at high elevation in recent years, the results of our study strengthen this hypothesis, calling for more extensive and in-depth studies on the subject.

Glaciated mountains of the Valle d’Aosta and Piemonte regions are described in relation to the geological, geomorphological and climatic settings of the Western Alps. A comprehensive view of the present-day Alpine regional cryosphere is offered, and links to regional and local examples of its evolution through the Quaternary are provided. Pleistocene moraine amphitheatres (Ivrea and Rivoli-Avigliana) of the piedmont area recall the development stages of Alpine glaciology. Major glaciers (Lys, Miage, Belvedere, Rutor and Sabbione) of the highest peaks of the Western Alps (Mt. Bianco, Mt. Rosa) are analysed for their specific scientific, environmental, cultural and economic importance. The distinctive dynamic nature of the glacial landscape is illustrated by examples of active glacial landforms and related slope instability, whose sensitivity to climate changes can increase hazards and risks.

One of the impacts of climate warming in recent years is the evident increase of the number of rock fall occurrences at high elevations. With few exceptions, these events have small magnitudes and thus are rarely reported and documented, even less so in the past. Therefore it is difficult to use a statistical approach to analyze of the relationships between climate warming and rock slope instability. On the other hand, it is often difficult to carry out a time analysis of meteorological conditions responsible for rock fall triggering, considering that very few automatic weather stations (AWS) are located in the areas and in the altitudinal range that are affected by cryosphere degradation (i.e. above c.a. 3,000 m elevation in the Alps), and that climatic conditions in high elevation environments are spatially and temporally variable. The present study addresses the above-mentioned issues through analysis of a series of small rock falls that occurred in the last 10 years on the Matterhorn and surrounding rock slopes. A specific focus is temperature: we present a preliminary analysis of the spatial and seasonal variability of the vertical temperature gradient in the Conca di Cervinia, where the Matterhorn is located, to illustrate the uncertainty in estimates of the thermometric conditions at high elevation rock fall sites.

Extraordinary development s are taking place at Ghiacciaio del Belvedere near Macugnaga, Valle Anzasca, in the Italian Alps. A surge-type  ow acceleration started in the lower parts of the Monte-Rosa east face, leading to strong crevassing and deformation of Ghiacciaio del Belvedere, with extreme bulging of its orographic right margin. High water pressure and accelerated movement lasted into winter 2001/2002: in places, the ice is now starting to override moraines from the Little Ice Age. In addition, but fairly independently , a most active detachment zone for rock falls and debris  ows has been developing for several years now in the east face of Monte Rosa. Besides the scienti Ž c interest in these separate phenomena, both events affect the growing hazard potentia l to the local infrastructure and must be considered seriously.