&gt; This is not a problem of big cities as such but one that Beijing (and China more generally) has because it has only recently transitioned from a developing country.<p>That&#x27;s where it happens: Big cities in developing countries.<p>&gt; scalable to and sustainable for the projected 10 Billion population.<p>Are ten billion sustainable at all? In Megacities? Will it be more sustainable to have them living mostly in Megacities? I don&#x27;t believe those theories that these cities are more sustainable.