The point here is that it isn't black and white and furthermore, whether you like it or not, taking care of earth is a political problem in the most basic literal sense that you have to get people to do it.

Unless you are cooking up ideas on how to wipe the human race out like some kind of mad scientist, and presumably kill yourself afterward, the fact is, people need to be convinced to modify their lifestyle/culture somehow. Telling them to simply die without children ain't gonna do it.