I always give the analogy of the Earth at Night picture, of 7.3 billion of us, right? And everyone says, "Well, that's population." Well, if you took the entire world's population and you lived at the density of Manhattan proper - not a bad place to live - how much space do 7.3 billion people take up? The state of Colorado. At which point I end my lectures, because I want you to be thinking ... is this really a question of population, or is this a question of land use and resource consumption? And let's face it, the top 1.3 billion of us are doing all the damage. Sorry.
