This whole "have one fewer child" thing is totally bonkers, because even on the face of it, it really only makes sense for people in Western nations with their current lifestyles. It's also an average over all the people in that country, meaning it's heavily spoiled by rich kids. Essentially, 1. you can't know beforehand how your child will live and 2. emissions don't scale linearly with the number of people (again, look at the difference between countries). And then there's the anti-humane undertone of it.