Sensitivity of the snow energy balance to climatic changes: prediction of snowpack in the Pyrenees in the 21st century

Abstract

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...

Effects of climate change on the intensity and frequency of heavy snowfall events in the Pyrenees

“…In general a slight underestimation was observed in the simulated values, except for HSEs in Góriz, where some overestimation occurred. These results are consistent with previous findings of the capacity of RCMs to simulate seasonal precipitation and temperature over the Pyrenees (López-Moreno et al 2008a), magnitude heavy precipitation events and their contribution to total precipitation (López-Moreno and Beniston 2009) and snowpack evolution (López-Moreno et al 2008b, 2009). …”

“…However, a number of important uncertainties are associated with climate models, particularly related to precipitation extremes, posing difficulties for simulation (Frei et al 2003;Giorgi 2005), and a robust validation cannot be easily achieved. Probably, a replication of the analysis with others RCMs dataset will lead to similar results in sign (López-Moreno et al 2008b), but different numbers in terms of magnitude of the change. As the main objective of the paper is not to provide a precise forecast of snow events in the future (an impossible task with the current uncertainties in climatic simulations), the paper aims to broadly demonstrate how heavy snow events may change in a "greenhouse climate".…”

“…A2 is characterized by higher emissions than B2 (IPCC 2007;Nakicenovic et al 1998). López-Moreno et al (2008b) demonstrated that simulated change in snow accumulation and melting in a location of the Pyrenees were consistent among nine different RCMs from the PRUDENCE dataset. For this reason, it was preferred to present analyses based on a single RCM simulation (HIRHAM model) instead of a RCMs-ensemble, since this would undoubtedly lead to larger uncertainties (and/or dispersion) in the pooled results.…”

“…Such processes, expressed in terms of water and energy budgets, are computed in a surface energy balance model (SEBM) termed GRENBLS (details found in López-Moreno et al 2008b). This model is similar to a land surface model formulation of intermediate complexity such as those in Global and Regional Circulation Models (GCMs and RCMs), but it differs in the details.…”

Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales

“…En la mayoría de las montañas del mundo, se espera un marcado aumento de temperatura como consecuencia de las emisiones de efecto invernadero (Nogués Bravo et al, 2007;. Los modelos climáticos regionales sugieren que los cambios más significativos esperados en el Pirineo se relacionan con la temperatura, que es el principal parámetro implicado en los procesos nivales futuros (López- Moreno et al, 2008b). Las proyecciones climáticas para finales del presente siglo sugieren, respecto a las condiciones actuales, un descenso de hasta el 50-60% en el maximum snow water equivalent, un adelanto en un mes en la ocurrencia de la máxima acumulación anual de nieve y una reducción de la duración del manto de nieve en alrededor de dos meses.…”