From the WWF (World Wildlife Foundation) "Deeper Luxury" report found here (it's a 52-page PDF, FYI).
If everyone were to live like the average European, three planets would be needed to provide adequate quantities of natural resources – for the average North American, five planets would be required.13 It would be physically impossible for all the world’s poor to achieve greater wellbeing in the same ways that Europeans and North Americans have managed so far. Such wasteful development is possible only for a minority, and for a limited time. This is neither morally nor environmentally sustainable. Our challenge is to find ways to improve human wellbeing within natural limits; to stop living as though we had another planet to go to.