Who's left behind?
In regards to the writers on the range piece, "a macabre measure of the human footprint," most everybody's working with the idea of too many of us, except for those who believe there can never be too many of us because god's taking care of that (hcn, 10/13/08). For the rest, it leads directly to triage, priorities, and soft or hard eugenics.
Who should go and who should stay? Volunteers are generally misguided; often the self-sacrificing are the very people you'd want most to keep around. Those who insist on their own irrefutable right to be the center of whatever form the species takes after it trims itself to survival shape are often the very people you'd most want to leave behind.
Ken kesey saw years ago that the agitation for reduction in population could far too easily lead to the first culls being amongst the gadflies, rebels and non-cooperatives. In a sick world that is elevating passive, obedient thoughtlessness and crafty selfishness, active smart selfless guys will be marginalized.
Human beings aren't identical replaceable cogs. There are types, varieties, kinds of people. Right now the kinds of people who are protected by material success are not the people i'd nominate to represent us to the rest of the universe.