Yes, and no. I'm quite convinced that humanity can make a decent living for itself (i.e, more pleasant than that of the average current day human) even if we fuck up nature beyond our current day recognition. It's worth considering that more than half of humanity lives in urban environments, and a majority of land area is cultivated in some way.
However, that doesn't mean that we shouldn't worry, or shouldn't try.
Earth is our heritage, and what we make of it will be the legacy that future humans remember the 21st century by. I'd much rather have our great-great grandkids frolicking in the grass under a pearl blue sky than in concrete caves to protect them from neverending storms and scorching deserts.
"libertarian" my ass, seems authoritarian to me.