Really. I had to spell it out for you? You weren't able to infer it for yourself from the context of the discussion? It didn't occur to you at any stage that sociopolitical trends and pressures might be important in regulating immigration - a factor that has been aknowledged as a growth pressure right from the beginning of the discussion? I've given three specific examples, that you have thus far refused to address. I'm fairly sure that Germany illustrates this statement to be baloney. And there you go again, off on some tangent because you haven't understood the point being made. Only Germany's border isn't closed to its neighbouting countries, it's open, more open in fact than it has been since WW I. It's political asylum that's been restricted, and only because, as I'm fairly sure I've already mentioned, the German constitution automatically granted it to all those who sought it. Utter bollocks. You keep harping on about sustainability, but what are you actually afraid of? Running out of food? If the world were to subsist on wheat, and everybody in the world were to consume 750g of wheat per day, which is sufficient to provide them with a luxurious 2700 cal per day, and exceeds the RDI of almost all (major) nutrients and such - except calcium, then supporting 10 billion people 2,737 Mt of wheat to be produced annualy. This would require 3.4 million km^2 in total of land area to be used for the cultivation of wheat. It's been estimated that there are 5.5 million km^2 available for such use, of which we actually only need about half for additional wheat production for a population of 10 billion people to be sustainable. Incidentally, women only need 2000 cal/day, and make up about half the population, so it would have been more reasonable to use 2350 cal as an estimate, however... Running out of water? 10 Billion human beings require 438 km[sup]3[/sup] of water per yer, for all uses, and assuming that everybody everywhere is uses wet reticulation for effluent disposal. This can be reduced to 365 km[sup]3[/sup] per year if everybody everywhere is using water saving fixtures. There are globally, 505,000 km[sup]3[/sup] of rainfall annually, of which 107,000 fall on land. So, again, from the perspective of water consumption, a population of 10 billion can be sustainable. Energy? You've already demonstrated that if we're willing to sacrifice our deserts, and risk the climate changes associated with the changes in albedo (which might be able to offset by changes elsewhere, restricting climactic effects to local) then we've got plenty of energy to spare. And all of this is only considering land based technologies, land making up only 25% of the surface of the earth, I've given no thought, for example, to things like hybrid solar-thermal-otec desalinization plants, OTEC power generation, or intensive aquacultural farming of kelp. All of which would ease the pressure on land based resources. It seems to me then that a population of 10 Billion people is sustainable, and even populations of 15-20 billion people may be sustainable, with investments in the right technologies, and as long as we can work on our small minded nationalistic ideaologies and traditions, and realize that we're part of a global environment and need to approach survival on a similar level.