A NOTE ON POPULATION (for Chan and Carrol):
1. At present on a global scale there is enough food to feed everyone.
2.But this is not always true locally. Local food production depends on
the use of land for fee or fuel or other non-food purposes;the price of
fertilizer compared to the price of grain; division of the farm among too
many heirs to its transfer to one heir and the expulsion of the others to
the city;natural disaster.
3 Over-and under population depends on the society and production system.
Medieval France was overpopulated with 10 million people.
4. Spontaneous or promoted reduction in the birth rate necessarily leads
to an aging population and a labor shortage for agriculture unless work is
radically redesigned to be compatible with aging bodies.
5.There are natural limits to production. The most productive natural
formations can fix about 10 T of carbon per hectare per year.The
vegetation ises only a small fraction of the incipient sunlight that is of
the right wavelength. More of it could be captured by technological means
such as the use of mirrors in gardens or devices that take unusable wave
lengths expend part of their energy, and give back light in the usable
spectrum. Nitrogen fertilizer can be fixed by microorganisms or industrial
means, but phosphorus has to be mined and jus running low.In ends up in
the sea and awaits underwater volcanoes and earth crust movement to
restore it.Deep sea mining again is highly fuel costly.
6. The limit of some 10 T/ha. Cannot be reached everywhere. Cloudiness
reduces the fraction of sunlight that can reach the crops. A rising
temperature will divert more of the energy captured by photosynthesis into
respiration.
7. Demography has to be included in long term planning.

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