21st Century alpine climate change

Abstract

A comprehensive assessment of twenty-first century climate change in the European Alps is presented. The analysis is based on the EURO-CORDEX regional climate model ensemble available at two grid spacings (12.5 and 50 km) and for three different greenhouse gas emission scenarios (RCPs 2.6, 4.5 and 8.5). The core simulation ensemble has been subject to a dedicated evaluation exercise carried out in the frame of the CH2018 Climate Scenarios for Switzerland. Results reveal that the entire Alpine region will face a warmer climate in the course of the twenty-first century for all emission scenarios considered. Strongest warming is projected for the summer season, for regions south of the main Alpine ridge and for the high-end RCP 8.5 scenario. Depending on the season, medium to high elevations might experience an amplified warming. Model uncertainty can be considerable, but the major warming patterns are consistent across the ensemble. For precipitation, a seasonal shift of precipitation amounts from summer to winter over most parts of the domain is projected. However, model uncertainty is high and individual simulations can show change signals of opposite sign. Daily precipitation intensity is projected to increase in all seasons and all sub-domains, while the wet-day frequency will decrease in the summer season. The projected temperature change in summer is negatively correlated with the precipitation change, i.e. simulations and/or regions with a strong seasonal mean warming typically show a stronger precipitation decrease. By contrast, a positive correlation between temperature change and precipitation change is found for winter. Among other indicators, snow cover will be strongly affected by the projected climatic changes and will be subject to a widespread decrease except for very high elevation settings. In general and for all indicators, the magnitude of the change signals increases with the assumed greenhouse gas forcing, i.e., is smallest for RCP 2.6 and largest for RCP 8.5 with RCP 4.5 being located in between. These results largely agree with previous works based on older generations of RCM ensembles but, due to the comparatively large ensemble size and the high spatial resolution, allow for a more decent assessment of inherent projection uncertainties and of spatial details of future Alpine climate change.

Recent waning snowpack in the Alps is unprecedented in the last six centuries

“…Information gained with SALP can help to improve state-of-the-art climate models to accurately represent snow on the ground in land surface models and properly consider snow dynamics variability at interannual to centennial time scales. This knowledge is essential to assessing whether models can correctly represent this challenging component of the cryosphere that combines modern forcing drivers with persisting natural variability 27,45 and is crucial to surface energy balance in the climate system and the hydrological cycle.…”

“…3-6). Snowpack duration was estimated during the snowy season considering two key components: a positive term related to the amount of solid precipitation and a negative one due to the melting process and related ablation of the surface snowpack mostly linked to temperature 27 . The snow degree-day model we applied is a simple snow cover model 28 ; however, simulating snow mass evolution solely from daily precipitation and temperature series permitted us to obtain a long record of snow cover duration (1834-2018), impossible to reach with more sophisticated approaches.…”

Quantifying the hydrological disturbances induced by snow grooming and snowmaking in ski resorts: a case study in the French Alps

“…In addition to simulations spanning previous years based on the SAFRAN reanalysis (Vernay et al, 2022), we introduce simulations under future climate change conditions. These simulations are based on one model run of the GCM/RCM pair CNRM-CM5/ALADINv6, part of the EURO-CORDEX ensemble (Jacob et al, 2014;Kotlarski et al, 2022) for the highemission scenario RCP8.5 for a 15 years time period in the middle (2043-2057) and the end (2083-2097) of the 21 st century.…”

Multi-decadal past winter temperature, precipitation and snow cover information over the European Alps using multiple datasets

“…Regional climate simulations driven by larger scale reanalyses are mostly used as a benchmarking tool to assess the reliability of climate simulations, used for climate projections. In Europe, climate simulations produced within the EURO-CORDEX framework have been used in various applications ranging from physical changes to climate change impacts (Jacob et al, 2014;Beniston et al, 2018;Terzago et al, 2017;Kotlarski et al, 2023). More recently, the EURO-CORDEX Flagship Pilot Study "Convection" has lead to the production of high resolution regional climate simulations using climate models at kilometer scale over a domain that covers the Alpine ridge (Coppola et al, 2020;Pichelli et al, 2021).…”