I wouldn't call it 'damage', and they really don't put out all THAT much steam.  I mean, well they do, but rivers and waterfalls put out a ton of water vapor too.
I'm sure I'm completely incorrect about hydrogen powered cars being bad because of water vapor produced, but I still think its interesting that water is the worst greenhouse gas (but it makes perfect sense).
I also find it too bad that so many people are against nuclear power, cause its SUCH a nice source of power!  As long as the waste is contained properly, it provides a lot of power for a long time.  All it is, is a steam plant, with really really hot water.
Nuclear rockets would be awesome too, but they won't do it cause if something goes wrong...  then you got a lot of nuclear material in the atmosphere, which is not such a good thing.
The next big wave is nuclear fusion power.  Interestingly enough, the aeronautics department at school has one of the leading fusion research programs.  Kinda wierd to think that a department like us would be looking in to that, but somehow we ended up with it!  I've seen the Helicity Injection Torus (HIT) before too, its CRAZY!!!
soooo, wait...  what does this have to do with skiing?
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Dont worry, its a controlled slide.