You are right of course, but it will take an attitude shift similar to that needed to eliminate racism. Until we start to see people who have more than two children as unacceptably selfish, population will continue to expand.
You've heard of "Disgusted, Tunbridge Wells"? Well, I live in Holland Park and I've Had It. Up to here! An old curmudgeon, I rant and rave about things I read, see or hear in the News. Frequently sarcastic, irreverent and libertarian; often wrong - but never uncertain.