>>I'm tempted to say the impact is very little, given that there aren't that many ski resorts. Of those that make snow, they might have less than 100 machines making snow, and only when it's needed.

There are quite a few ski resorts in the world, but more importantly they are - logically - situated in places with massive ecological importance. And you may be surprised how high-tech snow making has become, at least in the European Alps:

"One morning in 1995, Mattis, who was then a 28-year-old ski-lift engineer, was told he was being redeployed to look after the resort’s handful of snow machines. Four years later, he began building his snow-making factory, or atelier neige, installing a 70km network of pipes beneath the mountain that now, after years of expansion and improvement, can cover 65 sq km of slopes in artificial snow at the touch of a button. It is one of the most sophisticated snow-making operations in the world."

Source: https://www.theguardian.com/world/2019/dec/19/snow-machines-...