However, the point of my previous comment is that my comment before that was not saying that big cities would necessarily be unsustainable.
However, that food does have to come from somewhere, and we can not just wave a magic wand and exempt agriculture from the need to be sustainable, so that we can just feed the cities with massive factory farms employing some minute share of the population.
The most energy efficient source of fresh produce for the cities on a whole life cycle analysis will be truck gardens with very little trucking involved, shipped in from surrounding ex-suburbs along the same transport corridors that provide the energy efficient passenger transport. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
