You could say that about any economic activity. A greenhousing effect would also not be harmful to all or even most tourist sites. Your criticism just seems like a blanket criticism of human existence.
Any unnecessary and polluting economic activity that is actively killing the planet, yes.
> A greenhousing effect would also not be harmful to all or even most tourist sites.
I doubt that. If it won't be directly harmful in the next 100 years, there will be as many as 143 million people that'll be displaced due to climate change by 2050. Even if the tourist sites in question are in relatively safe locations such as Europe, you will most certainly not recognize them.
>>Any unnecessary and polluting economic activity that is actively killing the planet, yes.
All economic activity pollutes, and therefore according to your logic, is "actively killing the planet".
And if you want to be Spartan about it, a significant portion of economic activity is unnecessary, so your criticism is equally applicable to a major share of everything humans do.
In reality people need more than the basic necessities, and will pursue more than them. You're not offering a reasonable way forward with your over-critical analysis that singles out tourism as a harmful activity because of a particular set of properties that it has, that are shared by numerous other activities.
One could argue that, by accounting for eight per cent of the world’s carbon emissions, tourism is killing the sights along with the planet.