A new study published in Nature Climate Change and co-authored by former MRI Science Leadership Council member, Samuel Morin, warns that a quarter of European ski resorts could face snow scarcity every other year due to 2°C of global heating, raising doubts about their future. This Carbon Brief guest post digs into the details.
The ski tourism industry plays a major role in the economies of many of Europe's mountain regions.
But declining snow cover as a result of climate change is disrupting ski resorts across the continent, dramatically increasing the number of days where no skiing is possible.
As a result, these resorts are increasingly turning to artificial snowmaking as an adaptation measure to produce reliable snow cover for their pistes.
However, the effectiveness of snowmaking is highly variable and its use is controversial in mountain areas.
In our new study, published in Nature Climate Change, we assess the impacts of warming on 2,234 ski resorts across 28 European countries and the climate and water footprints of their future snowmaking needs.
Without snowmaking, we find that 53% and 98% of Europe’s ski resorts are projected to be at very high risk for snow supply under global warming of 2C and 4C, respectively.
Using snowmaking to achieve 50% snow coverage on their pistes, these figures are reduced to 27% and 71% of ski resorts, respectively.
But additional snowmaking will have an impact, too – by increasing water and electricity demand and adding to the considerable carbon footprint of the ski industry, which is typically mostly due to transportation and housing.
Our study is the first Europe-wide assessment of future snow scarcity and the environmental impact of snowmaking, taking into account the geography and characteristics of individual ski resorts.
Climate change risk
Europe is the world’s largest ski tourism market, with around 50% of the world’s total ski resorts and more than 80% of the world’s ski resorts that exceed 1m skier visits per year.
But the snow on which these pistes rely is at risk as global temperatures rise. In the Alps, for example, snow cover has dropped to levels that are “unprecedented” in the past 600 years.
We study the potential impact of climate change on the snow supply risk to ski tourism at the scale of the entire European ski tourism market. The map below shows the 18 regions the study covers, where the rings indicate the total surface area of ski pistes for each region.
Map showing the distribution of ski resorts in mountain areas in Europe. The map covers the 18 regions considered in the study (including six subdomains of the European Alps), which are colour-coded. The rings show the corresponding total estimated surface area of ski pistes for each region (totalling 984km2 as of November 2022). Adapted from François et al (2023)
Snow cover is the key ingredient for ski tourism and there are multiple ways to translate snow data into information relevant for the operations of ski resorts. This requires a definition of the suitable conditions for operations in a given year and how statistics need to be computed to assess climate change risk.
For example, a typical approach is to check whether snow depth exceeds 30cm for at least 100 days, but this offers limited relevance when it comes to accounting for the variability of snow conditions within the ski resort, with and without snow management.
For ski resorts, operators need to know how frequently they can expect to face snow-scarce conditions, rather than just the average amount of snow they receive each year.
In our study, we first estimate the fraction of the surface area of a ski resort with a sufficient amount of snow on a given day – typically, 20cm of “groomed” snow (that is, snow that has been packed and levelled by a vehicle).
We then calculate the average of these daily values over the period from December to February. This is called the “snow reliability index”, which we calculate for each ski resort.
We define snow-scarce conditions as the worst 20% of years in terms of groomed natural snow encountered during the reference period of 1961-90 – the golden age of the development of most ski resorts in Europe. This 20% threshold value is specific to each individual resort.
We then quantify the climate change risk affecting snow supply to ski tourism as the frequency of winter seasons with a snow reliability index lower than the threshold value.
Decline in snow conditions
Using a dataset initially developed for the sake of the Copernicus Climate Change Service (C3S) Mountain Tourism Meteorological and Snow Indicators (MTMSI) described in a previous publication, combined with extensive geospatial modelling of ski resorts, we find that, in a warming climate, snow conditions decline systematically, but not uniformly, across Europe’s ski resorts.
Indeed, while snow conditions decline more or less in line with the amount of warming, the potential impact on snow reliability at individual ski resorts varies greatly from one mountain range to another and within each mountain range.
Without snowmaking, 53% and 98% of the 2,234 ski resorts studied in 28 European countries are projected to face a “very high” risk of low snow cover under global warming of 2C and 4C, respectively, above pre-industrial levels.
Snowmaking can lessen this impact substantially. Assuming that a resort implements snowmaking over half of its pistes, the corresponding impact falls to 27% and 71%.
However, this would be accompanied by an increase in demand for water and electricity for snow production, increasing the costs and carbon footprint of ski resort operations.
In addition, covering half of a resort with the ability for snow production does not necessarily go hand-in-hand with substantially improved snow conditions in a warmer climate. And increasing water and energy requirements goes against efforts to reduce the environmental impact of tourism.
Furthermore, the presence of snowmaking equipment does not guarantee that it can be used when needed – for example, if temperatures are too warm.
Burning embers and snowy peaks
The figure below summarises our findings by region across Europe in the form of a “burning embers” graphic against different levels of global warming. Each region has four bars, with the left-hand bar showing natural snow only and the three bars to the right showing different levels of snowmaking fractional coverage.
The snow-supply risk in the burning embers graphic is measured by the frequency of snow-scarce winters. The baseline risk level of 20%, based on warming of 0.6C for the reference period, is classed as an “undetectable change” in risk level.
From there, a frequency of 30%, corresponding to a 50% increase in the frequency of snow-scarce conditions compared to the reference value (20%), is referred to as ”moderate” risk (yellow), while a doubling in the frequency (40%) is referred to as ”high” risk (red).
The risk reaches the ”very high” (violet) domain at a frequency of 50% and above, corresponding to snow-scarce levels seen at least once every two years, which was only encountered once every five years during the reference period.
The circles display relative changes in water demand for snowmaking compared to the reference period. The darker blue shading indicates a larger increase in water demand, while red shading indicates a reduction.
Burning ember representation of the snow supply risk to ski tourism in European mountain areas. Burning embers display the risk value, that is, the frequency of snow-scarce winters, using snow conditions without snowmaking for 1961-90 (corresponding to +0.6C of global warming level since 1850-1900) as a reference. For each geographical entity, the left bar refers to natural snow only (including grooming) and the three other bars account for different levels of snowmaking fractional coverage. The colours of the bars represent snow supply risk, from undetectable (white) to moderate (yellow), high (red) and very high (violet). Circles display relative changes in water demand for snowmaking compared to the situation for a fractional snowmaking coverage of 25% during the reference time period 1961-90. Source: François et al (2023)
In relative terms, the increase in the risk to snow supply with global warming, without snowmaking, is comparable across regions – but it starts from very different baselines.
Taking snowmaking into account, the situation shows more contrast. For some mountain areas – mainly in the Alps, but also in the Nordic mountains and in Turkey – additional snowmaking reduces the risk of snow scarcity. However, the marginal benefit decreases, especially between 50% and 75% (block a in the burning embers figure).
For other areas, snowmaking has a positive impact on the risk level up to a certain point. However, increases in the snowmaking coverage beyond 50% reduces its efficiency and the risk increases (see block b). This includes pistes in the Pyrenees and Carpathians.
Last, in some areas, the risk level quickly reaches high values with increasing global warming level, regardless of the snowmaking fractional coverage (block c). This includes the British Isles and Iberian mountains.
Environmental impacts
On a European scale, under the assumption of artificial snowmaking covering 50% of pistes, snow production requires around 100m cubic metres of water per year for the reference period 1961-90. This represents an average of 13% of the annual precipitation (rainfall and snowfall) reaching the slopes equipped for snowmaking.
(Here we focus on the 12 main countries in terms of the total snowmaking amount, comprising 95% of the ski resorts’ surface area considered in this study.)
We find that water demand changes substantially in a warmer climate, both in terms of the total quantity and its seasonal distribution.
For a 50% coverage of artificial snow, our projections indicate an overall increase in annual water demand of 8% to 25% at 2C of warming, depending on the country, and by 14% to 42% at 4C. This is driven mainly by mountain regions where climate conditions remain sufficiently cold for snowmaking at least occasionally during the winter season at a sufficiently high elevation.
For example, this is the case for the pistes in block A of the burning embers graphic, which includes the Nordic mountain regions, Turkey and most of the Alps.
We also find a general decrease in water demand for snowmaking in November due to increasing temperatures leading to fewer time periods that are suitable for snowmaking.
In general, electricity consumption and the carbon footprint evolve in similar proportions. For the reference period, we estimate snowmaking used around 300 gigawatt hours (GWh) of electricity annually, producing approximately 80,000 tonnes of CO2e – although this varies greatly from one country to another depending on how their electricity is generated.
We project this will reach 93,000 tonnes of CO2e per year at 2C of warming and 97,000 tonnes of CO2e at 4C.
Impacts of ski industry
Our study, along with several previous studies, pinpoints the critical role of snowmaking in altering the magnitude of the impact of climate change on snow conditions in ski resorts.
Addressing the evolution of snow conditions in ski resorts under a warmer climate should absolutely take snowmaking – routinely implemented by ski resorts – into account.
Our approach enables us to quantify some of the environmental impacts of snowmaking, but not all. For example, disturbances to local ecosystems for snowmaking infrastructure, such as the creation of local reservoirs, are probably one of the most critical aspects to take into account for local decision-making.
Although it can vary substantially at the local scale, we find a modest influence of snowmaking on the overall electricity demand and carbon footprint of ski resorts.
However, snowmaking cannot be detached from the broader tourism sector. Transportation and housing play a far greater role in the carbon footprint of ski tourism destinations, and snowmaking epitomises the considerable challenge between climate change adaptation and mitigation in the ski tourism industry.
It remains a collective challenge for this industry and, more generally, the authorities responsible for preserving mountain societies and ecosystems, to make a meaningful contribution towards decarbonation to stem global warming, while also adapting to the risks of a changing climate.
Citation: François, H. et al. (2023) Climate change exacerbates snow-water-energy challenges for European ski tourism, Nature Climate Change, doi:10.1038/s41558-023-01759-5
This guest post article was first published by Carbon Brief. You can find the original summary on their website.
Cover image by Yeray Sánchez
