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The occurrence of El Niño has been generally considered the main driver of hydro‐geomorphic processes in Peru. However, the climatic characterization of hydro‐geomorphic events (HGE) occurring in the absence of El Niño remains scarce. Information contained in the DesInventar disaster database suggests a widespread occurrence of HGE associated to cold‐neutral sea surface temperature (SST) in the central Pacific and south tropical Atlantic. Here, we aim at characterizing synoptic patterns associated with HGE that have occurred over last 35 years related to the different El Niño types and focusing as well on the non‐Niño phases. We use the ERA‐Interim reanalysis climate data and implement self‐organizing maps to assess the link between HGE in Peru and specific synoptic patterns. Results suggest that synoptic patterns associated with La Niña and neutral conditions play an important role in the occurrence of hydro‐geomorphic disasters in Peru during the austral summer. A total of 21% of the events are associated only with the 1972–1973, 1982–1983 and 1997–1998 El Niño events and are mainly focused in the northern Pacific coast of the country (i.e., Tumbes, Piura and Lambayeque) while more than 36% of the recorded events in the database were associated with La Niña and neutral conditions between 1970 and 2013. La Niña‐related events were more relevant in the Andean–Amazonian regions, whereas neutral conditions were related to more frequent HGEs in the southern regions (south of the 13.25°S) along the Peruvian Pacific coast. These outcomes imply an enhanced understanding of the synoptic mechanisms leading to the occurrence of HGE and contribute to a better understanding of the triggers of HGE causing disaster no exclusively related to El Niño‐like years in Peru. [ABSTRACT FROM AUTHOR]

This paper evaluates the response of stream flow and other components of the water balance to changes in climate and land-use in a Pyrenean watershed. It further provides a measure of uncertainty in water resources forecasts by comparing the performance of two hydrological models: Soil and Water Assessment Tool (SWAT) and Regional Hydro-Ecological Simulation System (RHESSys). Regional Climate Model outputs for the 2021-2050 time-frame, and hypothetical (but plausible) land-use scenarios considering re-vegetation and wildfire processes were used as inputs to the models. Results indicate an overall decrease in river flows when the scenarios are considered, except for the post-fire vegetation scenario, in which stream flows are simulated to increase. However the magnitude of these projections varies between the two models used, as SWAT tends to produce larger hydrological changes under climate change scenarios, and RHESSys shows more sensitivity to changes in land-cover. The final prediction will therefore depend largely on the combination of the land-use and climate scenarios, and on the model utilized. [ABSTRACT FROM AUTHOR]

A storm loss model that was first developed for Germany is applied to the much smaller geographic area of the canton of Vaud, in Western Switzerland. 24 major wind storms that struck the region during the period 1990-2010 are analysed, and outputs are compared to loss observations provided by an insurance company. Model inputs include population data and daily maximum wind speeds from weather stations. These measured wind speeds are regionalised in the canton of Vaud following different methods, using either basic interpolation techniques from Geographic Information Systems (GIS), or by using an existing extreme wind speed map of Switzerland whose values are used as thresholds. A third method considers the wind power, integrating wind speeds temporally over storm duration to calculate losses. Outputs show that the model leads to similar results for all methods, with Pearson's correlation and Spearman's rank coefficients of roughly 0.7. Bootstrap techniques are applied to test the model's robustness. Impacts of population growth and possible changes in storminess under conditions of climate change shifts are also examined for this region, emphasizing high shifts in economic losses related to small increases of input wind speeds. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses the predictions of the changes on precipitation and temperature of Pyrenees mountain range at the end of the 21st century with the use of the six regional climate models (RCMs). Considering the mean values of the region, their spatial distribution patterns and inter-model variability, the accuracy of the RCMs and the impacts of climate change in the region are analyzed. The results show that the effects of climate change will be more pronounced in the southern slopes range and lower in the coastland areas of Pyrenees. Other major findings of the analysis are also presented.

Summary The extreme values of a particular climatological variable determine the thresholds of vulnerability of different environmental systems. Extremes of temperature, beyond a given threshold, may exert irreversible damage on ecosystems, for example, while winds exceeding a given limit will have numerous impacts on vegetation and human infrastructure. The results of the present study highlight the change in the seasonal temperature limits at different latitudes and altitudes in Switzerland. Winter minimum temperatures at high altitude sites and summer maximum temperatures at low altitude sites in the north, in particular, have changed considerably during the last decade. Since annual extremes are seen to occur either during summer or winter, and much less during the intermediate seasons of spring and autumn, the change in summer and winter extremes are likely to have a significant impact on a number of biospheric, cryospheric, hydrologic and managed systems. [ABSTRACT FROM AUTHOR]