SF has a population density of 18,679 per square mile. NYC has 27,000. There is plenty of room, you'd just have to scale everything along with it.
Also, for what it's worth, > population density = < net pollution. mass transit etc. are great optimizations of resources. these humans already exist - it's just a matter of where they exist.
Also, for what it's worth, > population density = < net pollution. mass transit etc. are great optimizations of resources. these humans already exist - it's just a matter of where they exist.