Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

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Climate Change 2007: The Physical Science Basis.

Changes in climate extremes and their impacts on the natural physical environment: An overview of the IPCC SREX report

Prefaces Acknowledgements 1. Mountains and their climatological study 2. Geographical controls of mountain meteorological elements 3. Circulation systems related to orography 4. Climatic characteristics of mountains 5. Regional case studies 6. Mountain bioclimatology 7. Changes in mountain climates Appendix General index Author index.

Mountain Weather and Climate

Landslides in a changing climate

Glacier lakes are a common phenomenon in high mountain areas. Outbursts from glacier lakes have repeatedly caused the loss of human lives as well as severe damage to local infrastructure. In severa...

Remote sensing based assessment of hazards from glacier lake outbursts: a case study in the Swiss Alps

Debris flows from glacier forefields, triggered by heavy rain or glacial outbursts, or damming of streams by ice avalanches, pose hazards in Alpine valleys (e.g. the south side of Mount Blanc). Glacier‐related debris flows are, in part, a consequence of general glacier retreat and the corresponding exposure of large quantities of unconsolidated, unvegetated, and sometimes ice‐cored glacial sediments. This paper documents glacier‐related debris flows at 17 sites in the Italian, French, and Swiss Alps, with a focus on the Italian northwest sector. For each case data are provided which describe the glacier and the instability. Three types of events have been recognized, based on antecedent meteorological conditions. Type 1 (9 documented debris flows) is triggered by intense and prolonged rainfall, causing water saturation of sediments and consequent failure of large sediment volumes (up to 800 000 m 3 ). Type 2 (2 debris flows) is triggered by short rainstorms which may destabilize the glacier drainage system, with debris flow volumes up to 100 000 m 3 . Type 3 (6 debris flows) occurs during dry weather by glacial lake outbursts or ground/buried ice melting, with debris flow volumes up to 150 000 m 3 . A data base of historic cases is needed in order to advance process understanding and modelling, and thus improve hazard assessment.

Recent debris flow occurrences associated with glaciers in the Alps

. 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.

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Microseismic activity analysis for the study of the rupture mechanisms in unstable rock masses

Climate change impacts on mountain glaciers and permafrost

Extraordinary developments are taking place at Ghiacciaio del Belvedere near Macugnaga, Valle Anzasca, in the Italian Alps. A surge-type flow 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 flows has been developing for several years now in the east face of Monte Rosa. Besides the scientific interest in these separate phenomena, both events affect the growing hazard potential to the local infrastructure and must be considered seriously.

A surge-type movement at Ghiacciaio del Belvedere and a developing slope instability in the east face of Monte Rosa, Macugnaga, Italian Alps

High runout distances characterize landslides falling on glaciers because of (1) low friction offered by ice to sliding and (2) complex rock-ice interactions that take place during mass motion. Block-fall models (two (2D) and three dimensional (3D)) were tested on the 1936 Felik landslide (Mount Rosa Massif). Geotechnical parameters were assessed through a back-analysis aided by field surveys, aerial photo and historical data analysis. Outcomes are verified for two rock-ice avalanches which ran along the Brenva Glacier (Mount Blanc Massif) in 1920 and 1997. Empirical models show poor precision (75%). 3D numerical models are too complex but 2D ones gave results that pointed out that real runouts exceed predicted ones by 30%, possibly due to fluidization processes. Rock-ice avalanches require attention because they originate in areas likely destined to experience permafrost degradation and glacier retreat. Copyright © 2002 John Wiley & Sons, Ltd.

Marta Chiarle

Papers

Recent debris flow occurrences associated with glaciers in the Alps

Microseismic activity analysis for the study of the rupture mechanisms in unstable rock masses

Climate change impacts on mountain glaciers and permafrost

A surge-type movement at Ghiacciaio del Belvedere and a developing slope instability in the east face of Monte Rosa, Macugnaga, Italian Alps

Modelling rock avalanches and their relation to permafrost degradation in glacial environments