The present paper analyses and quantifies the sensitivity of snowpack to climate change, and assesses implications for snow processes in the central Pyrenees under the climatic conditions projected by a set of 9 regional climate models (RCMs) for the end of the 21st century, under the IPCC emission scenario SRES A2. The methodology was based on comparison of the snow series obtained by simulating the energy balance of a snow surface driven by climatic conditions recorded during the period from 1996 to 2006, with snow series obtained by simulations for the same period that included various changes in magnitude for each of the climatic drivers (sensitivity analysis); and the changes projected by the RCMs to the end of the 21st century. Results showed a marked sensitivity of snowpack duration and thickness to shifts in temperature, precipitation and solar radiation. RCMs suggest that the most significant changes expected in the study area are related to temperature, which is the main parameter responsible for the predicted changes in future snow processes. A large coherence was found among the simulations made using the projections of the 9 regional climate models. Comparison with respect to current conditions indicated a decrease of 50 to 60% in maximum snow water equivalent, the occurrence at least 1 mo earlier of the maximum snow water equivalent, and a reduction in the duration of the snowpack by around 2 mo. In addition, the 3 snow parameters will be subject to a marked increase in inter-annual variability compared to the observed conditions. KEY WORDS: Snow · Snow energy balance · SEB · Climate change · Regional climate models · RCMs · Pyrenees Resale or republication not permitted without written consent of the publisherClim Res 36: 203-217, 2008 from December to April in areas >1500 m above mean sea level (a.s.l.), with a longer duration of snow cover at higher altitudes and in shaded areas (García-Ruiz et al. 1986, López-Moreno & Nogués-Bravo 2005. In this region, snow controls many ecological processes and also has important socio-economic implications, mainly due to (1) the large contribution of snow melt to the amount and seasonal distribution of runoff in Pyrenean river basins, which plays a major role in water management in the semiarid and highly populated Ebro valley (López-Moreno & García-Ruiz 2004) and (2) the significant development of winter tourism in recent decades, which represents one of the main sources of revenue for the region. Thus, this area could be particularly sensitive to the impact of expected climatic change in the 21st century (López-Moreno et al. 2008).Within this context, the aim of the present study was to assess the impact of predicted climate change on snow processes in the Pyrenees. For this purpose, the snow energy balance (SEB) in the area was simulated for climatic conditions in the recent past (1996 to 2006) and for future conditions driven by projections of 9 different regional climate models (RCMs) for the end of the 21st century. The use of a multi-mod...

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