[lb1lf]

While urbanisation overall is probably a net plus for the environment, do keep in mind that, say, farming is quite area intensive.

Someone needs to work at those farms - and they are not going to commute to work by high-speed rail.

(Granted, there are experimental urban farms out there, but I don't see those feeding the planet on a short-term scale.)

[adrianN]

Farming is area intensive, but the number of farmers we need has been steadily declining.