[en] Highlights: • First use of multi-criteria decision analysis for glacial lake outburst flood risk • Method uses free and widely available data and software without need for fieldwork. • Method can be applied to any region of the world and to any glacial lake type. • Sensitivity analyses and comparison to previous work demonstrate robust results. • Method applied to Bolivia, illustrates three lakes as medium/high risk. Glacial Lake Outburst Floods (GLOFs) represent a significant threat in deglaciating environments, necessitating the development of GLOF hazard and risk assessment procedures. Here, we outline a Multi-Criteria Decision Analysis (MCDA) approach that can be used to rapidly identify potentially dangerous lakes in regions without existing tailored GLOF risk assessments, where a range of glacial lake types exist, and where field data are sparse or non-existent. Our MCDA model (1) is desk-based and uses freely and widely available data inputs and software, and (2) allows the relative risk posed by a range of glacial lake types to be assessed simultaneously within any region. A review of the factors that influence GLOF risk, combined with the strict rules of criteria selection inherent to MCDA, has allowed us to identify 13 exhaustive, non-redundant, and consistent risk criteria. We use our MCDA model to assess the risk of 16 extant glacial lakes and 6 lakes that have already generated GLOFs, and found that our results agree well with previous studies. For the first time in GLOF risk assessment, we employed sensitivity analyses to test the strength of our model results and assumptions, and to identify lakes that are sensitive to the criteria and risk thresholds used. A key benefit of the MCDA method is that sensitivity analyses are readily undertaken. Overall, these sensitivity analyses lend support to our model, although we suggest that further work is required to determine the relative importance of assessment criteria, and the thresholds that determine the level of risk for each criterion. As a case study, the tested method was then applied to 25 potentially dangerous lakes in the Bolivian Andes, where GLOF risk is poorly understood; 3 lakes are found to pose ‘medium’ or ‘high’ risk, and require further detailed investigation.

[en] After a recall of some definitions (extreme events, risks related to extreme events) and a discussion of the way extreme meteorological events are addressed by social sciences, this publication proposes an overview of extreme climatic events which occurred in the past and are occurring now by addressing observations, human and financial costs. It also outlines the relationship between already observed changes and human activities. Then, it discusses the future impact of climate change on major natural risks. The next part addresses the prevention and management of risks related to extreme climatic events (issues of adaptation, of mobilisation of all actors, of a structured and long-term policy which articulated additional actions, examples of implementation of measures to reduce vulnerability and exposure to risks). The document also contains the activity report of the ONERC (the French national observatory of effects of global warming)