In reply to _hs_:
Climbing and the environment. Skiing and the environment. Windsurfing and the environment. I have similar opinions on all of these.
Firstly, I think that gear is a complete non-issue because gear isn't disposable or single-use. Sure, it's all made out of stuff that is hardly "green" and the manufacturing is also not "green" but I try to buy really good stuff, look after it carefully and use it hard until it dies. I'm not buying new stuff every season just for fashion and I'm not buying crap just to look at it. (The carbon in my windsurf masts is well captured in my opinion.)
Consumables are perhaps a concern but, seriously, none of these sports have any high consumable consumption rate. I use a bag of chalk every few years. I need to toss my old fins and buy new ones but the old ones were 99% knackered by previous owners before I even bought the boards they came with and so they were already "recycled" in a way -- it's only through liberal use of elbow-grease and sandpaper that I've kept them useful for two seasons already. Skins don't wear out that quickly and what's the environmental impact of a ski grind, buff and wax once a season?
Climbing shoes are probably the worst "consumable" of all and I try to get mine resoled at least once in their life cycle. I normally have a pair of good outdoor shoes for sends, old-but-good shoes for outdoor adventure climbing and tries and nearly-knackered shoes for in the hall. Shoes filter down this hierarchy and, by the time they're not even good for the boulder hall, they've been properly used to death. I'm not happy with the life-span of climbing shoes but I try to mitigate the problem as much as possible.
And NONE of my sports involve bottled water, pre-packaged dehydrated meals or single-serving sachets of energy-gunk. I actively loath those.
The biggest impact must be driving. Climbing without driving is awkward but more possible than ski-touring. Windsurfing without driving is basically impossible -- bike trailer arrangements do happen but, frankly, they're not really practical for most people.
But when I'm on a surfing trip, I drive to the spot and leave the car standing for a week -- or use it only for very short hauls from the camp-site to the rigging lawn. Similar for skiing: one long slog to the village and then standing or short hops from the house to the start of the trail. Certainly, I drive less on holiday than I do for work during the work week.
Plus, when I'm on a skiing, climbing or surfing trip, I'm not sat at my desk drinking shite coffee out of corporate-issue aluminium nespresso pods, eating food out of single-use packaging, or ordering cruft off Amazon to afford a distraction from the shitness of work life etc.
As far as impact on the environment is concerned, I try to be as stealthy as possible. That is, I leave only footprints and take only photographs and whatever. I try not to destroy the flora or the rock when I'm climbing and, unlike some, I don't go trying to launch my windsurfer in protected areas where birds may be nesting or other wildlife sanctuary exists. Similarly, I ALWAYS observe crag bans related to bird nesting seasons, bats etc. And I have no respect for anyone who ignores these.
I have often wondered about the impact of skiing but surely ski touring is even less impact than hiking because you're only eroding snow and that will melt in the spring, anyway? (I ski in resorts, too, but only because they're already there. I am strongly against building more of them or enlarging them -- enough lifts exist, already -- and I loath fake snow, which even sucks to ski on. (I'll take a rest day over a fake-snow day, any day of the year!))
Contrast climbing, ski touring and windsurfing to other sports that I enjoy, however. What about tennis? I must go through buckets of balls per year -- far more, by weight, than climbing shoes. And only a few of them find uses after tennis. (Top uses for old tennis balls: dogs, friends with kids, "greek" beach tennis, foot arch self-massage (aka. sneaky under-the-desk toy for bored programmers), and shoving under windsurf foot-straps to preserve their shape in transit. Also: cluttering up basements.)
Clay court tennis also requires liberal use of water on the court, settling the dust before each use -- hardly a problem in Germany but it must be wasteful in other places in the world.
In conclusion, I do not consider any of my favourite sports to be really harmful, relatively speaking. Sure, optimisations could be made but there's a hell of a lot more that could be done, first, for greater impact. Killing the aluminium Nespresso pod, for example!