> Carbon footprint depends on energy sources, Obviously true. > Carbon footprint [does not depend on] population density. Patently false. Carbon footprint ca

> Carbon footprint depends on energy sources, Obviously true. > Carbon footprint [does not depend on] population density. Patently false. Carbon footprint can depend on more than one variable, and indeed does. Transportation of goods and people is a huge source of carbon, all of which goes way down in cities. > it doesn't matter whether they live in isolated households or in one skyscraper. It's much easier to heat every room in a skyscraper than isolated households due to volume vs. surface-area scaling, even if you hold square footage equal. But square footage is not equal; people occupy less space in skyscrapers, because of redundancy in amenities (shared garages, laundry, recreational areas) and other reasons.