I don't know. There was a certain Thomas Malthus who was quite convinced that the standard of living in the 1800s was the highest nature would permit, and any country which wanted to avoid famine would need to virtuously restrain itself from seeking to consume more. Maybe it's different this time, and we really are at the limits of what nature will support, but I think we need some explanation of how we know we're not repeating his lack of imagination.