Gactimus wrote:
How many people can the earth support?

Bloated, wasteful Americans or semi starved African Pygmies?

This is the first question to ask.

The others are quality of life, technology, and how cooperative and
altruistic the people are assumed to be.

You can feed a LOT of people on pure spirulina, grown in the equatorial
ocean deserts. But nobody would WANT to live.

Best way to stabilise population is to make the individual lives comfortable
( and that means supporting everyone, with fair distribution of accumulated
wealth, not just in the hands of a few, as well as renewable energy and high
technology ) so that individual struggles for procration and security from
large families are diminished.

Concentration of population in a relatively few area ( arcologies would be
nice for the aging populations ) so that everyone feels 'crowded' already,
while maintaining proportions of pure wilderness barred from human
settlement. both on land and in the oceans. This would ensure that
populations never went over the carrying capacity of the planet, since the
only hunting, fishing and farming would be in the remaining areas and the
reservees would ensure that it never got large enough to start an extinction
from harvesting pressures.

But who'se dreaming? The people in charge are not looking for solutions to
the woes of the world. They are looking for thier own advantage, so no
amount of speculation will affect the reality of declining ecosystems and
increases in poor populations.