If you are interested in the previous dialog on dieoff this is the thread:
http://www.peakoil.com/fortopic1687.html
If one looks at a chart of the human population over the last 1,500 years, the departure from a steady, but very small yearly increase, began a little after 1600AD. This departure became increasingly dramatic, and is now in a nearly vertical climb. It took all of human history to reach about 500,000 population, and in less than 400 years we climbed from 500,000 to 6.5 billion.
There was a reason that the population never before climbed to the present dramatic level, and I think that reason was that we only figured out how to get enough surplus at any one time to support less than 500,000. Technology is the knowledge to make use of resources; both must be present, and as our knowledge increased and was applied to resources, we generated greater and greater surpluses, hence population levels responded to the availability of things to support it, and also increased. I think there is an obvious cause and effect.
I think that in the future population levels must follow the availability of things to support us. It should be obvious that energy technology is at the base of this surplus explosion; the oil age, as discussed throughout this board, is about to come to a relatively abrupt end. I think the best bet is that human population will snap back to historic norms as the rest of the energy age ends.
Ultimately, I think we must return to what we know the planet can support absent the energy and resources we have depleted, and this level is under 500,000. All the remaining energy and resources will not disappear overnight, so Duncan's argument that the initial dieoff will take us back to about 2 billion by 2050 is to my mind reasonable. We can judge what the planet can support at various energy/resource levels from past experience.
In response to the ever reducing level of energy/resources many will experience conservation, then deprivation, then death. The argument that we can all live in deprivation indefinitely, as the third world does today, does not take into account the crumbs from the industrial world that find their way to assist these who supposedly live without the benefit of todays surpluses, nor does it consider what the effect would be if life expectancy in the industrial population fell to that in the third world.
We had our party, even though some were not invited, and the hangover is next.