The people who have kids are also the ones causing the most harm to the environment. The single most effective way to diminish your impact on the environment is to not reproduce.
It's also the most selfish way, in some regard. My wife and I just recently had our first after some time, and one of the biggest factors involved was how selfish it would be not to. A lot of parents feel the same way; you need to appreciate that it's not in black and white and there are multiple perspectives.
The future for them is very bleak. The pros/cons of facing it is a hard decision to make. Personally, I'd hate to make that decision for someone else, let alone a person I would end up caring about the most.
I would say that it depends in many factors. It could be that a single wealthy person in a city in USA consumes and produces waste as a family of 10 in a rural area in Africa. Thus seems that there are plenty of other ways to diminish your impact.