About 20 years ago, when I was a grad student, I attended a colloquium where the speaker (a physicist, for better or worse) had computed the number of people th

About 20 years ago, when I was a grad student, I attended a colloquium where the speaker (a physicist, for better or worse) had computed the number of people that the planet could support if everyone consumed natural resources at the rate that Americans do. His number was 2 billion. I don't remember who the speaker was and I don't know what assumptions he made -- I don't know how much error there might be in his result or how improvements in technology might change it. If his number is even close to being right, "global populations will peak in my lifetime" isn't even close to being adequate unless you expect the bulk of the population to be satisfied with remaining poor while a small proportion of the population devours the planet.