Winter Tourism Under Climate Change in the Pyrenees and the French Alps: Relevance of Snowmaking As a Technical Adaptation
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The Cryosphere, 13, 1325–1347, 2019 https://doi.org/10.5194/tc-13-1325-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Winter tourism under climate change in the Pyrenees and the French Alps: relevance of snowmaking as a technical adaptation Pierre Spandre1,2, Hugues François1, Deborah Verfaillie2,3, Marc Pons4, Matthieu Vernay2, Matthieu Lafaysse2, Emmanuelle George1, and Samuel Morin2 1Univ. Grenoble Alpes, Irstea, UR LESSEM, Grenoble, France 2Univ. Grenoble Alpes, Université de Toulouse, Météo-France, CNRS, CNRM, Centre d’Études de la Neige, 38000 Grenoble, France 3Barcelona Supercomputing Center, Barcelona, Spain 4Snow and Mountain Research Center of Andorra, IEA, Sant Julià de Lòria, Andorra Correspondence: Samuel Morin ([email protected]) Received: 18 November 2018 – Discussion started: 20 December 2018 Revised: 19 March 2019 – Accepted: 2 April 2019 – Published: 24 April 2019 Abstract. Climate change is increasingly regarded as a threat only 24 resorts are projected to remain reliable with snow- for winter tourism due to the combined effect of decreas- making, all being located in the Alps. ing natural snow amounts and decreasing suitable periods for snowmaking. The present work investigated the snow relia- bility of 175 ski resorts in France (Alps and Pyrenees), Spain and Andorra under past and future conditions using state- of-the-art snowpack modelling and climate projections us- 1 Introduction ing Representative Concentration Pathways RCP2.6, RCP4.5 and RCP8.5. The natural snow reliability (i.e. without snow- The ongoing evolution of natural snow conditions related making) elevation showed a significant spatial variability to climate change (Beniston et al., 2018) is increasingly in the reference period (1986–2005) and was shown to be regarded as a major threat for winter tourism (Gilaberte- highly impacted by the ongoing climate change. The reli- Burdalo et al., 2014; Steiger et al., 2017; Hoegh-Guldberg ability elevation using snowmaking is projected to rise by et al., 2019). This prompts the question of how climate 200 to 300 m in the Alps and by 400 to 600 m in the Pyre- change affects ski resorts and the relevance of snowmaking nees in the near future (2030–2050) compared to the refer- as an adaptation measure (Steiger et al., 2017). Initial stud- ence period for all climate scenarios. While 99 % of ski lift ies in the early 2000s quantified the snow reliability of ski infrastructures exhibit adequate snow reliability in the refer- resorts based on the “100 days” rule, later considered as the ence period when using snowmaking, a significant fraction reference approach for investigations of climate-induced im- (14 % to 25 %) may be considered in a critical situation in pacts on the winter tourism (Koenig and Abegg, 1997; El- the near future. Beyond the mid-century, climate projections sasser and Bürki, 2002; Abegg et al., 2007; Steiger, 2010; highly depend on the scenario with either steady conditions Pons-Pons et al., 2012; François et al., 2014). This rule states compared to the near future (RCP2.6) or continuous decrease that a ski resort is snow reliable if the snow depth exceeds in snow reliability (RCP8.5). Under RCP8.5, our projections 30 cm during 100 d or more, which provides objective in- show that there would no longer be any snow-reliable ski re- formation when comparing distinct periods (past and future) sorts based on natural snow conditions in the French Alps or locations (Koenig and Abegg, 1997; Elsasser and Bürki, and Pyrenees (France, Spain and Andorra) at the end of the 2002; Abegg et al., 2007; Durand et al., 2009b). The snow century (2080–2100). For this time period and this scenario, reliability line is defined as the elevation above which these conditions are met, allowing the assessment of the reliability of a ski resort by comparing its elevation to the snow reliabil- Published by Copernicus Publications on behalf of the European Geosciences Union. 1326 P. Spandre et al.: Winter tourism under climate change in the Pyrenees and the French Alps ity line (Koenig and Abegg, 1997; Elsasser and Bürki, 2002; 1961–1990 reference period in the southern Ontario region Abegg et al., 2007; Gilaberte-Búrdalo et al., 2017). (Canada) which were shown to significantly decrease un- Most investigations based on the 100 days rule used der projected climate conditions despite an increasing need single-point representations of ski slopes to assess the snow for snowmaking. Scott et al.(2006) later used this mod- and meteorological conditions of a given ski resort, often us- elling approach and a 60 cm snow base depth requirement ing the median elevation of a ski resort defined as the aver- in the Quebec region (Canada). Steiger and Mayer(2008) age of summit and base elevations (Abegg et al., 2007; Scott applied this method in Tyrol (Austria) and concluded that et al., 2003; Steiger, 2010; Dawson and Scott, 2013; Pons snowmaking could guarantee snow reliability at elevations et al., 2015; Gilaberte-Búrdalo et al., 2017). Schmidt et al. above 1000 m a.s.l. for the 1971–2000 reference period and (2012) and Rixen et al.(2011) used the “highest”, “mid- would remain a suitable adaptation method until the 2050s dle” and “lowest” elevations of the study area while Hen- with a significant increase in water and energy requirements nessy et al.(2007) mixed various approaches by consider- (Steiger, 2010). Similar investigations were conducted to as- ing either a single point or three distinct elevations for each sess the impact of climate change on the ski season duration ski resort. Alternatively, Pons-Pons et al.(2012) considered and the snowmaking requirements so as to compensate for the lowest and highest elevations, between which 75 % of the loss in regions of Austria (Marke et al., 2014; Hanzer the ski slope surface area was concentrated. These remain et al., 2014), Germany (Schmidt et al., 2012), Switzerland coarse representations limiting the analysis of the situation (Rixen et al., 2011), Andorra (Pons-Pons et al., 2012), the of a ski resort to a binary conclusion of reliable or unreli- Pyrenees (Pons et al., 2015; Gilaberte-Búrdalo et al., 2017), able (Steiger et al., 2017). Koenig and Abegg(1997) and El- the northeastern US (Dawson and Scott, 2013), New Zealand sasser and Bürki(2002) in Switzerland and later Abegg et al. (Hendrikx and Hreinsson, 2012) and Australia (Hennessy (2007) in the rest of the European Alps based their analy- et al., 2007). Major limitations remain. First, little investi- sis on the natural snow conditions. Abegg et al.(2007) re- gation was undertaken in France, still a major area for winter viewed the existing literature to address the snow reliability tourism (François et al., 2014; Steiger et al., 2017). Second, line for regions of Europe (Austria, Italy, Germany, Switzer- meteorological and snow input data considered for the anal- land and France) based on distinct methods and reference ysis were aggregated over large regions (Abegg et al., 2007; periods (Laternser and Schneebeli, 2003; Wielke et al., 2004; Damm et al., 2017) where high spatial variability can be ob- Matulla et al., 2005). They concluded that 91 % of the 666 ski served (Durand et al., 2009b; François et al., 2014). Third, resorts in the European Alps were snow reliable around 2005. snow conditions were often simulated using simplified de- Significant spatial variations in the snow reliability line were gree day modelling approaches (Dawson and Scott, 2013; shown, ranging from 1050 to 1500 m above sea level (a.s.l.) Hendrikx and Hreinsson, 2012) and neglected the differences with consequences on local reliability of ski resorts: 69 % of between natural snow and groomed or machine-made snow ski resorts were snow reliable in Germany and up to 97 % properties (Pons et al., 2015; Gilaberte-Búrdalo et al., 2017). were snow reliable in Switzerland and France. Abegg et al. The present work aims at producing snow reliability in- (2007) similarly addressed the impact of climate change on vestigations of a wide range of ski resorts in France (Alps the snow reliability line and concluded that under a C 1 ◦C and Pyrenees), Spain and Andorra under past and future con- warming compared to present only 75 % of European Alps ditions using state-of-the-art snowpack modelling. We ac- ski resorts would remain reliable and respectively 61 % and counted for snow grooming and snowmaking using a de- 30 % for C2 and C4 ◦C warming compared to the present tailed snowpack model (Spandre et al., 2016b) and used ad- would remain reliable. These investigations were limited to justed and downscaled climate projections from the EURO- the analysis of natural snow using average conditions over CORDEX dataset (Verfaillie et al., 2017, 2018) to compute large regions. Steiger(2010) later showed by the analysis of snow reliability elevations with distinct levels of snow relia- 52 climate stations in Austria over the 1981–2001 period that bility requirements. The mean elevation of residential popu- an elevation of 1200 m a.s.l. could not be confirmed as snow lation in a ski resort (Breiling and Charamza, 1999) and the reliable for all regions of Tyrol (Austria). Using natural snow mean elevation of ski lifts (Falk and Vanat, 2016) were com- conditions to assess the snow reliability of ski resorts has also pared to the snow reliability line. We defined seven distinct been questioned, due to the strong role of snow management, categories for ski resorts based on their natural snow relia- in particular grooming and snowmaking (Hanzer et al., 2014; bility, their degree of dependence on snowmaking to achieve Spandre et al., 2016b; Steiger et al., 2017). reliability (Pons et al., 2015) and whether snowmaking may Recent studies have increasingly taken into account snow be a technically efficient method to guarantee snow reliabil- grooming and snowmaking (Scott et al., 2003, 2006; Steiger, ity under present and future climate conditions.