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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.

Water quality and availability are nowadays essential requirements for all those activities that need an exploitation of the water resource: e.g. potable use, hydroelectricity production, agriculture, recreation. Inland water originates from atmospheric events and is stored in solid state as glaciers or snow (e.g. on the mountains) or in natural and artificial lakes at any altitude. The well documented climate warming has, among its multiple effects, the modification of the equilibrium between liquid and solid phase of water, its storage and availability, as well as changes in the precipitation regime, such as the reduction and intensification of rainfall events alternated to long dry periods. All these changes alter water quality and water availability at the catchment level.We are experimenting the use of earth observation data (Sentinel-2) to track temporal variations of snow cover, water bodies (in terms of size and numbers) and water colour over the last five years in a small high-altitude, glacierized catchment in Italy (Lake Ceresole watershed, Orco Valley, Western Alps). In particular, water colour is chosen here as a proxy of water quality and is considered as mainly driven by the presence of suspended particles, because of the conditions that feature a mountainous environment (e.g. minimized anthropic pressure and prevailing natural processes). Water colour is then supposed to change following the release of suspended particles from snow/glaciermelting during thaw periods at seasonal timescale, as well as be modified due to the transport of solid particles as river flow or runoff, which can be generated as a consequence of heavy rainfall events.Satellite derived products on snow cover, lake size/number and water colour are then coupled with meteorological measurements (e.g. precipitation), and information on geo-hydrological events (e.g. floods) in order to find possible linkages between lake water dynamics and both snow/glaciermelting and significant meteorological and geo-hydrological events. Field measurements allow a validation of the satellite data on lake water colour to be performed. With this study, we aim to understand if the high spatial resolution of Sentinel-2 acquisitions, except for the drawbacks of all optical satellite sensors (e.g. cloud cover), can provide useful information on water and sediment dynamics in an alpine glacierized basin, that can allow to follow the on-going modifications that the mountainous environment is facing due to the global warming. The use of Sentinel-2 data for this purpose would be a valuable tool in helping both monitoring and understanding of climate change consequences, and in managing the water resource in places not easily accessible for periodic in-situ measures. In fact, mountains respond promptly to climatic pressures, but are also the water sink of fresh water for downstream valleys.

In a context of cryosphere degradation caused by climate warming, rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes. In order to improve the knowledge of this critical relationship, it is necessary to increase measurement capability of rock temperature and its variability in different lithological and slope/aspect conditions, and also to increase local scale studies, increasing the quality and the comparability of the data. This paper shows an example of metrological characterization of sensors used for rock temperature measurement in mountain regions, by means of the measurement uncertainty. Under such approach, data and results from temperature measurements carried out in the Bessanese high-elevation experimental site (Western European Alps) are illustrated. The procedures for the calibration and field characterization of sensors allow to measure temperature in different locations, depths and lithotypes, within 0.10 °C of overall uncertainty. This work has highlighted that metrological traceability is fundamental to asses data quality and establish comparability among different measurements; that there are strong differences between air temperature and near-surface rock temperature; and that there are significant differences of rock temperature acquired in different aspect conditions. Finally, solar radiation, slope/aspect conditions and lithotype, seem to be the main driving factors of rock temperature.

High mountains are the realm of the cryosphere: snow, glaciers and permafrost give charm to mountain slopes, but at the same time protect them from atmospheric agents and contribute to their stability. Climate change, and in particular temperature increase, is however causing cryosphere reduction, exposing high mountains to an increasing instability. In this context, landslides are both an effect and an indicator of climate change impact on terrestrial systems. In particular from the hot summer of 2003, awareness of the ongoing climate change and its effects has gradually grown, thanks also to international research efforts. An alliance between citizens, public administrations and research institutions is urgently needed to understand the ongoing changes, develop future scenarios, and tackle climate change and its impacts.

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.

Il rapporto prende in esame i principali processi che concorrono alla pericolosità residua dei processi torrentizi, con particolare riguardo all'ambiente alpino.

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.

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.

Temperature is one of the most important aspects of mountain climates. The relationships between air temperature and rockfalls at high-elevation sites are very important to know, but are also very difficult to study. In relation to this, a reliable method to estimate air temperatures at high-elevation sites is to apply the altitudinal temperature lapse rates (ATLR). The aims of this work are to quantify the values and the variability of the hourly ATLR and to apply this to estimated temperatures at high-elevation sites for rockfalls studies. To calculate ATLR prior the rockfalls, we used data acquired from two automatic weather stations that are located at an elevation above 2500 m. The sensors/instruments of these two stations are reliable because subjected to an accurate control and calibration once for year and the raw data have passed two automatic quality controls. Our study has yielded the following main results: (i) hourly ATLR increases slightly with increasing altitude, (ii) it is possible to estimate temperature at high-elevation sites with a good level of accuracy using ATLR, and (iii) temperature plays an important role on slope failures that occur at high-elevation sites and its importance is much more evident if the values oscillate around 0 °C with an amplitude of ±5 °C during the previous time-period. For these studies, it is not enough to improve the knowledge on air temperature, but it is necessary to develop an integrated knowledge of the thermal conditions of different materials involved in these processes (rock, debris, ice, water). Moreover, this integrated knowledge must be acquired by means of sensors and acquisition chains with known metrological traceability and uncertainty of measurements.

MEDSCOPE - WP4 - Description and progress of different prototypes - Forecast of snowpack and glaciers Update of activities related to the project

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.

Rockfalls are common instabilities in alpine areas and can cause significant damage. Since high mountains have been affected by an increasing number of these phenomena in the last years, a possible correlation with permafrost degradation induced by climate change has been hypothesized. To investigate this topic, a monitoring system, made of 5 triaxial geophones and 1 thermometer, was installed in 2007 at the Carrel hut (3829 m a.s.l., Matterhorn, North-western Alps), in the frame of the Interreg IIIA Alcotra project n. 196 "Permadataroc". The preliminary data processing relates to the classification of recorded signals, the identification of the significant microseismic events and the analysis of their distribution in time and space. The first results indicated a possible correlation between clusters of events and temperature trend, and a concentration of events in specific sectors of the rock mass. Research is still in progress. The recording of data for a longer period is planned to fully understand seasonal trends and spatial distribution of microseismic activity, and possible relations with permafrost degradation. Nevertheless, the preliminary observations prove that the monitoring system can detect noises generated by rock slope deformation. Once fully developed, this technique could become a helpful tool for early warning and preliminary stability assessments.

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.

Climate change is seriously affecting the cryosphere, in terms, for example of permafrost thaw, alteration of rain/snow ratio, glacier shrinkage. There is concern about the increasing number of rockfalls at high elevation in the last decades. Nevertheless, the impact of climate variables on slope instability at high elevation has not been fully explored yet. In this paper, we investigate 41 rockfalls occurred at high elevation in the Italian Alps between 1997 and 2013 in the absence of an evident trigger. We apply and improve an existing data-based, statistical approach to detect the anomalies of climate parameters (temperature and precipitation) associated to rockfall occurrences. The identified climate anomalies have been related to the spatio-temporal distribution of the events. Rockfalls occurred in association with temperature anomalies in 83 % of our case studies. Temperature represents a key factor contributing to slope failure occurrence in different ways. As expected, warmer temperatures accelerate snowmelt and permafrost thaw; however, surprisingly, negative anomalies are also often associated to slope failures. Interestingly, different regional patterns emerge from the data: higher-than-average temperatures are often associated to rockfalls in the Western Alps, while in the Eastern Alps slope failures are mainly associated to colder-than-average temperatures. The results of this study represent a first step towards the identification of the possible role of climate change in the triggering of slope failures in a mountain environment.

Climate change is seriously affecting the cryosphere, in terms, for example of permafrost thaw, alteration of rain/snow ratio, glacier shrinkage. There is concern about the increasing number of rockfalls at high elevation in the last decades. Nevertheless, the impact of climate variables on slope instability at high elevation has not been fully explored yet. In this paper, we investigate 41 rockfalls occurred at high elevation in the Italian Alps between 1997 and 2013 in the absence of an evident trigger. We apply and improve an existing data-based, statistical approach to detect the anomalies of climate parameters (temperature and precipitation) associated to rockfall occurrences. The identified climate anomalies have been related to the spatio-temporal distribution of the events. Rockfalls occurred in association with temperature anomalies in 83 % of our case studies. Temperature represents a key factor contributing to slope failure occurrence in different ways. As expected, warmer temperatures accelerate snowmelt and permafrost thaw; however, surprisingly, negative anomalies are also often associated to slope failures. Interestingly, different regional patterns emerge from the data: higher-than-average temperatures are often associated to rockfalls in the Western Alps, while in the Eastern Alps slope failures are mainly associated to colder-than-average temperatures. The results of this study represent a first step towards the identification of the possible role of climate change in the triggering of slope failures in a mountain environment.

As stated by GCOS "Long-term, high-quality and uninterrupted observations of the atmosphere, land and ocean are vital for all countries, as their economies and societies become increasingly affected by climate variability and change". High-quality observation is possible only if based on a sustained traceability to SI and with documented uncertainties associated to the measured values. Following the signature of the MRA by the WMO , in April 2010, the CCT of the CIPM , in its XXV meeting of May 2010 submitted a recommendation to CIPM. The document highlighted the need to encourage National Metrology Institutes (NMIs) [...] to face new perspectives, needs, projects and activities related to the traceability, quality assurance, calibration procedures and definitions for those quantities involved in climate studies and meteorological observations and to support a strong cooperation between NMIs and Meteorological Institutions at local, national and international levels. In response to this call, several Joint Research Projects (JRPs) in metrology have been established. Their objective is to improve calibration procedures and measurement techniques for some Essential Climate Variables (ECVs), focussing especially on temperature, pressure and water vapour. Additional objectives have included investigations of sensor characteristics and the improvement of measurement devices and their use in the field. The impact effort is demonstrated also by the involvement of key international scientific Institutions such as GRUAN ,ISTI , IAPWS , and prominent Manufacturers and Universities. The overall aim is to make a further step towards establishing full data comparability, consistency and long-term continuity, through a comprehensive evaluation of the measurement uncertainties for the quantities involved in the global climate observations. The improvement of quality of ECVs records, through the inclusion of measurement uncertainty budgets, will also highlight possible strategies for the reduction of the uncertainty. This contribution will report on JRPs advances, events and task group activities, with the vision to establish a permanent bridge between metrologists and climatologists, through which to strengthen and develop collaborations, joint activities/projects and results dissemination to the whole society.

Recent climate changes are increasing the frequency of rock-slope instabilities in the Alpine region. The formation of cracks leading to rockfalls causes a release of energy propagating in form of elastic waves. These latter can be detected by a suitable transducer array together with the vibrations generated by the impact of rockfalls. Geophones are among the most effective monitoring devices to investi-gate both these phenomena. A monitoring system composed by geophones and thermometers was installed at the J.A. Carrel hut (3829 m a.s.l., Matterhorn, NW Alps) in the framework of the Interreg Alcotra projects PERMAdataROC and MASSA by CNR IRPI and ARPA with the financial and logistic support of the Valle d'Aosta Region. The correlation between temperature trends and microseismic events is presented: cold periods characterized by a rapid tempera-ture decrease present higher concentration of microseismic activity. However, not every drop in temperature is associated to microseismic activity, and the identifi-cation of the processes generating microseismic events in occasion of rapid tem-perature decrease is still uncertain. The objective of the ongoing research activity is to analyze in deep the statistical correlation between the number of microseismic records and the temperatures of air and rock in order to investigate the existence of recurrent patterns in the detected signals.

In 2011 a consortium of different institutions leaded by the Civil Protection Department of the Turin Province and including the CNR IRPI, the University of Turin and Thales Alenia, realized a 3D video simulation of a debris flow in motion. The 3D video, which is part of a larger installation that includes also the representation of a landslide and of a snow avalanche, allows a direct interaction with the process through a joystick. This latter, in fact, allows to change the viewpoint of the user, choosing an aerial view, a lateral one or a view that is closer to the ground permitting a more detailed observation of the phenomenon in its progress. The video has primarily instructional and educational purposes, enabling the user to acquire a personal reality of a debris flow and to become aware of its different aspects. It is also an example of the precious support that monitoring data may provide, since the virtual simulation was strictly based on real data recorded in field installations. The 3D video was created as a tool to support the communication activities devoted to explain to the general public the basic principles of civil protection through a direct involvement in a situation of danger. This involvement can be an important stimulus to better understand the natural phenomenon under investigation and to assimilate the basic behaviors needed for self defense. The video was realized with the funds of the European RiskNat project.

In the framework of the activities of the GeoClimAlp research group (Geomorphological impacts of Climate change in the Alps), a system of databases has been developed for the storage and management of glacial, periglacial and mountain digital resources, related to the Greater Alpine Region in general, and to the North-Western Italian Alps in particular. These resources are historical documents, publications, photos, aerial photographs, antique and recent maps, instrumental and survey data, related to: (i) alpine glaciers; (ii) natural instability processes and landforms in glacial/periglacial areas; (iii) hydro-climatic conditions of the alpine areas. This wealth of knowledge is mainly referred to the last 150 years. The GeoClimAlp digital resources stored in these databases are mainly used to: (i) study the spatial-temporal evolution of alpine glaciers; (ii) study the geomorphological processes, and in particular natural instability, that occur at high altitude (over 2000 m a.s.l.), in particular as a consequence of climate change; (iii) assess the hydro-climatic conditions of the glacial/periglacial and mountain areas; (iv) conduct research on climate change in the alpine environment.

The air temperature in the Alps has increased at a rate more than twice the global average in the last century, and a significant increase in the number of slope failures has also been documented, in particular in glacial and periglacial areas. Thus, the relationship between climatological forcing and processes of instability at high elevation is worth analyzing. We provide a simple, statistically based method aimed at identifying a relationship between climate factors and the triggering of geohazards. Our main idea is to compare the meteorological conditions at the time when the instability occurred with the typical conditions in the same place. Carrying out a straightforward analysis based on the use of the empirical distribution function, we are able to determine whether any of the meteorological variables had nonstandard values in the lead-up to the slope failure event, and thus to identify the variables that are likely to have acted as triggering factors for the slope failure. The method has been tested on five events in the glacial and periglacial areas of the Piedmont Alps (Northwestern Italy) occurring between 1989 and 2008. Out of these five case studies, our research shows that four can be attributed to climatic anomalies (rise of temperature and/or heavy precipitation). The results of this study may contribute to developing knowledge about the relationships between climatic variables and slope failures at high elevations, providing interesting insights into the expected impact of ongoing global warming on geohazards.