Both our population and the goods each of us uses are rising. Put the two together, and we stress our Island Earth very seriously. They ride mass transit. They live and work in centrally heated buildings. Centralized dining wastes less food.
City dwellers carry out every function of daily life more efficiently.
The huge power plants that supply cities are far cleaner per kilowatt hour than wood-burning stoves or kerosene lamps. That efficiency has a sad side effect. The poor go to cities. The efficiency of cities makes survival possible for those least able to consume. Yet on another level my historian friends are right.