Originally Posted by
ericy
Catton's book "Overshoot" in particular is relevant in that it discusses how a population can overshoot the carrying capacity of an ecosystem, which inevitably leads to a "die-off" at the end. In the case of humans, the thinking is that petrochemical inputs (such as fertilizers and pesticides) made the "Green Revolution" possible, which lead to an explosion in human population. Once we have exhausted the oil and natural gas that are the raw materials for the petrochemicals, then the 9 billion dollar question is how much food will we be able to produce, and will we be able to make enough to feed everyone? The people who have given this a lot of thought are guessing that the maximum sustainable human population is probably in the 1-2 billion range.
I have read Overshoot, and thought it was very very good. I do have a little argument with his position though, in that I think if we really did a "back to the earth" approach to sustainable farming, we could handle a 9 billion population (small, sustainabily run farms are often 3-4 times as productive as industrial farms per acre, but much more expensive in labor and dollars). It could be done, but we really would be gong back to more of a subsistance economy, and food would once again be 60-70% of your income like in the old days. The standard of living would drop off dramatically to make it work though.