The contrasting future of snow cover in 21st century French ski resorts

Two new studies on future changes to snow cover in Alpine and Pyrenean ski resorts in the 21st century, led by the National Center for Meteorological Research National Center for Meteorological Research or CNRM (whose Snow Research Center works in partnership with Météo-France, CNRS, University of Toulouse and University of Grenoble Alpes) and Irstea Grenoble’s LESSEM (Mountain Ecosystems and Society Laboratory) and ETNA (Stream Erosion, Snow and Avalanches Laboratory) units, have just been published in The Cryosphere (April 24, 2019) and Scientific Reports (May 29, 2019). The results will be use to quantitatively forecast the impact of climate change on snow cover in winter sports resorts.

For several decades now, snow cover in resorts has not been solely dependent on snowfall or natural changes to the snowpack, but also on the way in which the latter is managed by operators, using packing and snowmaking. Changing snow cover in ski resorts in a context of climate change is one of the main challenges of the 21st century for mountain land use. Climate change affects snow cover in several ways, leading to a reduction in natural snow cover, particularly at low altitudes, and influencing air temperatures and therefore the ability to produce artificial snow.

New snow level simulations for Alpine ski slopes

Researchers from CNRM and Irstea Grenoble have developed a range of tools that apply climate projections used by the IPCC for mountain ranges to simulate the evolution of the snowpack on ski slopes, taking into account packing and snowmaking. The physical impact of these interventions and their implementation methods (dates and times for packing, production criteria and targets, etc.) were modeled using face-to-face conversations and surveys with ski resort managers.

The modeling method also took into account the geography of each resort (altitude, orientation and slope distribution, location of ski lifts and areas covered by artificial snow). A set of tools is used to produce snow cover data for each ski resort and to estimate the volume of water required for snow production. The amount of water used is dependent on several factors, such as the area covered by the artificial snow, the production needs identified during the season to compensate for any deficits in natural snow cover, and snow gun yields.

The two studies described below used this approach to run simulations for the entire 21st century, incorporating several climate pathways, including a “low” scenario (significant reduction in emissions and carbon neutrality over the course of the century, RCP2.6) and a “high” scenario (continued increase in emissions, RCP8.5).

Snow cover in ski resorts © H. Bellot / Irstea

Snow cover in ski resorts © H. Bellot / Irstea

Study published in Scientific Reports

As part of this study, the tool set was applied to 129 ski resorts in the French Alps for a 45% level of artificial snow cover. This is the level of enhancement expected to be needed by around 2025. The main results of this project are:

  • First half of the 21st century: regardless of the chosen climate scenario, a 45% level of artificial cover will make it possible to maintain appropriate snow cover conditions for all resorts in a way that matches the reference scenario without artificial snow (1986-2005). Adverse snow cover remains a possibility for some years, but not more frequently than during the reference period.
  • Second half of the 21st century: After 2050, the situation will become relatively stable in the “low” scenario, while getting significantly worse by the end of the century in the “high” scenario.

The impact of warming on snow cover in ski resorts is high once global temperatures increase by 1.5°C and without artificial snow. With a 45% level of artificial snow, coverage remains comparable to that found currently for temperature increases of less than 2°C. However, once the temperature increases by more than 3°C, artificial snow is no longer enough to compensate for the reduction in natural snow.

The study also looked at the consumption of water across the Alpine region given a 45% level of artificial snow cover. During the reference period (1986-2005, average of 15% of the area covered in artificial snow), around 10 to 20 million m3 of water was consumed per year. Until now, increases in consumption have been mainly led by an increase in skiable areas requiring artificial snow cover. This will continue in the future, even if the level of additional cover needed stabilizes. For the 2030-2050 period, the estimated volume of water required is around 40 million m3, through this could vary between 25 to 50 million m3 depending on the year. In the second half of the 21st century, values stabilize for the “low” scenario (RCP2.6) but continue to increase for the “high” scenario (RCP8.5), despite the often inadequate snow cover.

The methods used in this study represent innovative tools that quantify the impact of climate change and the amounts of water required to produce artificial snow, which contributes to the discussion surrounding adaptation. For example, these tools could be used on a case-by-case basis for one or more resorts to take local characteristics into account for a more detailed analysis. Alternatively, they could be used to analyze hydrological disruptions caused by a specific ski resort as objectively as possible. However, snow cover is not the only criteria used to determine the socioeconomic viability of a ski resort, with political and economic considerations also playing their part.

Publication:

  • Spandre, P., H. François, D. Verfaillie, M. Lafaysse, M. Déqué, N. Eckert, E. George and S. Morin, Climate controls on snow reliability in French Alps ski resorts, Scientific Reports, www.nature.com/articles/s41598-019-44068-8

 

Study published in The Cryosphere

The study published in The Cryosphere uses a simpler method, which cannot calculate water requirements and does not take into account the orientation and slopes of the resorts. The general conclusions were nevertheless similar and were extended to include resorts in the French, Spanish and Andorran Pyrenees, where by the end of the century and in the “high” scenario, snow cover will be more adequate for skiing, even with artificial snow.

Publication:

  • Spandre, P., H. François, D. Verfaillie, M. Pons, M., Vernay, M., Lafaysse, E. George, and S. Morin: Winter tourism under climate change in the Pyrenees and the French Alps: relevance of snowmaking as a technical adaptation, The Cryosphere, 13, 1325-1347, https://doi.org/10.5194/tc-13-1325-2019, 2019.

 

For further information

Consult the web pages of the Mountain Ecosystems and Society Laboratory (LESSEM), Stream Erosion, Snow and Avalanches Laboratory (ETNA) unit and the Irstea Grenoble Center