By 2050, as few as 14–24 resorts across the French Alps and Pyrenees are projected to remain snow-reliable on natural snow alone — down from a much larger historical set. The same peer-reviewed work finds that 83–116 additional resorts stay viable only with snowmaking. The natural-snow list is shrinking; the snowmaking-supported list is what keeps the map populated.
That contrast is the whole story of Alpine adaptation in two numbers. Natural snow reliability is retreating uphill as the climate warms, and the resorts that survive the transition are overwhelmingly the ones that can manufacture snow through the marginal window. This piece lays out where those numbers come from, what "snow-reliable" actually means, and why the marginal-hour problem is the one worth solving.
Key takeaways
- Only 14–24 French Alps and Pyrenees resorts are projected to stay reliable on natural snow by 2030–2050; 83–116 more remain viable only with snowmaking (Spandre et al. 2019, The Cryosphere).
- The snow-reliability elevation line rises roughly 200–300 m in the Alps and 400–600 m in the Pyrenees under the studied warming — pushing many resorts below the reliable band.
- Across Europe, 53% of 2,234 resorts face very-high snow-scarcity risk at +2 °C without snowmaking; with 50% snowmaking coverage that falls to 27% (François et al. 2023, Nature Climate Change).
- "Snow-reliable" is a defined threshold — the 100-day rule — not a vibe; it is why marginal days are existential rather than cosmetic.
- Snowmaking is the load-bearing adaptation, and its binding constraint is the marginal wet-bulb window — the warm nights when snow is hardest to make.
Where does the "14–24 resorts" number come from?
From a 2019 study in The Cryosphere that modelled snow reliability resort-by-resort across the French Alps and Pyrenees. Spandre and colleagues found that, on natural snow alone, only 14–24 resorts across those ranges would meet the snow-reliability standard by the 2030–2050 horizon — while 83–116 additional resorts remained viable specifically because snowmaking closes the gap.
The mechanism behind the shrinkage is elevation. As temperatures rise, the altitude at which natural snow is dependable moves up the mountain. The same study puts that shift at roughly 200–300 m in the Alps and 400–600 m in the Pyrenees. A resort whose terrain sat comfortably inside the reliable band can find its base — and sometimes its mid-mountain — dropping below it, even though nothing about the resort changed but the climate around it. That baseline of what "reliable" has historically meant is set out in the 100-day rule.
This is a projection under specific warming scenarios, not a forecast of closures. It describes snow-scarcity risk, and the honest reading is that natural reliability contracts while managed reliability — via snowmaking — holds a much larger set of resorts in play.
Is the shrinkage a future projection or already underway?
Both — the trend the projections describe is already measurable in the snowpack. A 2023 reconstruction in Nature Climate Change found that the recent Alpine snow season is running about 36 days shorter than the long-term mean, a decline unprecedented in 600 years (Carrer et al. 2023), with snow cover falling roughly 5.6% per decade over the last half-century. The reliable band is not waiting for 2050 to move; it has been retreating for decades.
The longer baseline tells the same story. The OECD's Alpine assessment (after Abegg) counted about 500 naturally snow-reliable areas at +1 °C of warming, falling to 404 at +2 °C and roughly 202 — around 30% — at +4 °C, with the reliability line near 1,200 m in Switzerland rising about 150 m per additional degree. Read together, the historical reconstruction and the forward projections describe one continuous contraction: fewer naturally reliable areas, a reliability line climbing the mountain, and an industry that has already shifted its base of operations from natural to managed snow to stay in business.
What does "snow-reliable" actually mean?
It means meeting the 100-day rule: enough snow cover of skiable depth on at least 100 days per season in most years. The rule comes from Alpine tourism economics — roughly the coverage a resort needs to run a viable winter — and it is the yardstick these studies apply. A resort is "snow-reliable" if it clears that bar on natural snow in a defined majority of years, typically seven in ten.
That definition is why marginal days matter so much. The question is rarely whether a resort gets any snow; it is whether it clears 100 skiable days often enough to stay in business. Losing the early-season and shoulder days — the warm, marginal ones at each end of winter — is what drops a resort below the threshold. The reliability baseline and its history are set out in the 100-day rule, and the revenue weight of those early days in what missing Christmas costs a resort.
The economic consequence of a bad natural-snow year is not abstract. US skier visits fell roughly 14% in 2025–26 in a weather-driven downturn — a live demonstration that snow reliability, not skier appetite, is the swing variable for the industry's revenue.
How much does snowmaking change the picture?
Dramatically — it is the difference between a decimated map and a manageable one. The François et al. 2023 study in Nature Climate Change, covering 2,234 resorts across 28 European countries, found that at +2 °C of warming, 53% of resorts face very-high snow-scarcity risk without snowmaking. With snowmaking covering 50% of terrain, that risk share drops to 27% — roughly halved.
| Warming level | Very-high snow-scarcity risk, no snowmaking | Risk with 50% snowmaking coverage | |---|---|---| | +2 °C | 53% of resorts | 27% | | +4 °C | 98% of resorts | 71% |
Warming thresholds, not calendar years. Source: François et al. 2023, Nature Climate Change (2,234 EU resorts).
Two things follow. First, snowmaking is not a marginal convenience; it is the single most effective adaptation lever in the peer-reviewed record, moving tens of percentage points of risk. Second, it is not a cure at the extremes — at +4 °C even full-effort snowmaking leaves the majority of resorts at high risk, because you cannot make snow in air that is simply too warm. Whether resorts survive the transition is the subject of what the 2050 data shows.
The scale of dependence is already visible: Italy makes snow on roughly 90% of its skiable terrain and Austria on about 75%. The Alps do not ski on natural snow now; they ski on managed snow, and the managed list is what these studies are really tracking.
Where does the marginal window fit in?
It is the exact seam where snowmaking either saves a resort's season or fails to. Snowmaking loses its power not gradually but at a threshold — the wet-bulb temperature above which a snow gun cannot freeze its droplets before they land. As warming pushes more nights above that line, the reliable set shrinks in step with the lost marginal hours, not with average temperature.
This is why the reliability numbers and the operational numbers are the same story. Every resort that Spandre's model keeps "viable with snowmaking" is a resort winning its marginal window often enough. Anything that widens that window — colder guns, better siting, or chemistry that lets snow form at a higher wet-bulb, as covered in making snow at warmer temperatures — directly enlarges the set of resorts that clear the 100-day bar. The additive route to those extra hours is a modelled +3 °C wet-bulb advantage, described in what SL6733 is.
That reframes the shrinking-list narrative from fatalism to engineering. The natural-snow list will keep contracting; the question for any given resort is how much of its lost marginal window it can buy back.
The bottom line
The list of naturally snow-reliable Alps is genuinely shrinking — to as few as 14–24 resorts in the French ranges by mid-century on natural snow alone. But the peer-reviewed record is equally clear that snowmaking keeps 83–116 more in play, and halves very-high scarcity risk across Europe at +2 °C. The decisive variable is the marginal wet-bulb window: the resorts that survive are the ones that can make good snow when it is almost, but not quite, cold enough. That is where efficiency and chemistry earn their place — not by reversing warming, but by widening the window in which snow can still be made.
If you want to understand how much of your marginal window is recoverable, request a pilot or get in touch.
Climate projections cited here describe snow-scarcity risk under defined warming scenarios, not closures or calendar-year forecasts. SL6733 operator outcomes, including the +3 °C wet-bulb figure, are modelled; the additive is pre-commercial. DeepSnow is the platform brand of SnowLabs Limited (Ireland); DeepSnow Srl (Italy) is in formation.