Hi Luca
I have worked on the bridges connecting Raxual in India to Kathmandu (Seven Bridges) few years back... and I find that Nepal is the most sustainable community in the world. The things that are changing in the top Himalyan region has actually got nothing to do with either Nepal, India or China... its the direct effect of Global warming. I have travelled to Gangotari where the mightiest river (also the most revered and pure) Ganges start from and followed the river through out its stages up to Bay of Bengal and realised that again it does get polluted but still it has not added to the global warming or the snow cap reduction. (Only now I have fears when they are making huge dams and we even did agitation to stop it along with the Professor from IIT - Premier Technical institute of India but not much difference) As Bina also suggested that India China and Nepal has not much to do with this Himalayan cap which has the worlds 40% of fresh water  from declining. What we need is awareness and working even individually to bring in more people to this fold. I have started in my own small way in Chennai India ( http://www.greencitizens.blogspot.com ) and may be all of us can do the same.
Have a look at another blog where my travels to the most holiest places, journey along Ganges as well as into himalaysa are recoreded http://www.virtualcitizen.blogspot.com

Hope for the best...

Om Namah Shivaya
Virtual