Living in fear? It's living in reality.
There are lots of kids whose life prospects and quality of life would benefit greatly from being adopted. In my view, if I chose to have my own kid instead of adopt, I'm essentially abandoning what could be an adopted kid seeing as I don't view DNA relation as critical to a family.
Bringing another person into the world is the single most damaging decision I can make regarding my environmental impact.
If there's no difference to me, personally, between having my own kid and adopting one, why would I have my own when considering #1 and #2?
I'm not "living in fear" by being conscious of these factors, and they're enough of a reason for me to not produce my own kid without even considering the prospects of my kid's future quality of life in an increasingly polluted world.