I think you can safely files stories entitled, "Tourism a Huge Threat to Global Environment", under "Duh!"

As more and more people have the wherewithal to travel beyond their borders to check out the wonder that is the rest of the world, they tend not to follow the backpackers motto of "leave only footprints and take only pictures". Nor do they follow the golden rule as in treat another country as you would treat your own. (Or maybe, they do, which would explain a lot about where you come from).

Travelers, tourists, visitors, whatever, tend to treat other countries like garbage dumps. Tourists sites around the world are littered with rubbish. We've been hearing for years about trash left behind by climbers at Everest base camp. I've been some awful stuff in my travels from pits full or plastic waters bottles in Thailand to totally wrecked coral reefs in Indonesia to piles or trash left by pilgrims on Mt. Sinai (Yes, that Mt. Sinai).

Everywhere you look you'll find examples of tourism destroying the environment and you don't need fancy multi-million dollar investigations or UN sponsored reports to see it.

And this is just the phycial damage. The psycological impact is probably far worse. The damag sone to indigenous culture by the pollution of western media is immeasurable and, sadly, irrevocable.

The big question is what is to be done about it. Certainly, you're going to have a hard time stopping tourists.

You can read more about it here:

Tourism Impacts - UNEP Tourism

Tourism a Huge Threat to Global Environment