Quote Originally Posted by thir View Post
We are so many people who use the planet so hard that the whole thing is in fact our habitat. And we are responsible for our actions, being the sentient species.
Nope. There are vast sections of the planet which are not habitable by humans, not without major technological help, mainly from those living in habitable areas. If we destroy the ecosystems of those habitable areas, there will be no place left for us to go, at least not where we can maintain our civilization.

No, life wil not just neccesarily go on.
One thing modern science has shown us is that life is extraordinarily tenacious. No matter what mankind can do, there will be some form of life which will not only survive but will thrive in the new ecology. Humanity may not be here to see it, but the possibility that we could completely sterilize the planet is so remote as to be next to impossible. Even if we managed to destroy the planet, breaking it up into fragments whirling around the sun as another asteroid belt, there will likely be microscopic life surviving on some of those fragments. Humanity's problem is to make certain that we don't destroy ourselves. The planet, and life, can take care of themselves.