From: szabo@techbook.com (Nick Szabo)
Subject: Re: population load question
Organization: TECHbooks --- Public Access UNIX --- (503) 220-0636
Date: Wed, 9 Sep 1992 16:29:23 GMT

In article <1992Sep5.205454.24674@meteor.wisc.edu> tobis@meteor.wisc.edu (Michael Tobis) writes:
>It's an ill-defined question as it stands. Do you expect energy supplies
>to be limited or unlimited? Do you expect wild environments to be protected
>or destroyed? Do you expect people to be affluent, barely comfortable, or
>desperate? Do you believe that raw materials will be supplied from space
>or not? 

These are boolean questions; nothing is either fixed or unlimited. The real 
answers are tradeoffs between each factor, limited primarily by technological 
sophistication and social structures.

>(I think the last point is moot, as in a steady state earth will
>not have much to offer extraterrestrially based people in trade unless
>the natural environment is preserved. However, others may argue.)

I will argue, since this is very far off the mark.  For a 
long time to come, space industry will need the design inputs of many 
bright people, and will also import most of its culture.  The limiting
factor in Earth imports is probably the ability of Earth's atmosphere
to absorb reentering mass (we currently absorb a few thousand tons per
year of meteors naturally).  This may limit imports to things like
catalysts, machine tools, isotopes, pharmaceuticals, etc. Even a few
thousand tons of this stuff can greatly enrich Earth industries from energy 
to manufacturing to agriculture, so low mass does not imply low
influence on the course of our planet.  Also, a mature space
industry will probably give us the ability to export more than 
1 billion people a year from Earth into space, via beanstalks
manufactured in space, if that capability is ever needed (it probably
will not be because of demographic trends).

>I think that if one specifies a rough balance between speciation and
>extinction, current levels of population, and current levels of affluence
>and impact, the answer is clearly less than the current population.

By the middle of the next century the species extinction crisis will be
solved, at least for those of us interested in preserving the genetic 
library, not every habitat in its "pristine nature".  The latter is
almost entirely an aesthetic issue, and far inferior to the culture
that can created by 10 billion more talented people on this planet,
not to mention the habitats, dwarfing any on Earth in size and diversity,
that can be made in space with their help.

>So let me rephrase the question: assume that the world lives well, with
>an affluence comparable to, say, Connecticut. Assume no major technological
>brieakthroughs or changes in life style, except that energy remains
>available at current prices. Assume that there is no net loss of wilderness
>area, and less than 10% loss of remaining species. WHAT IS THE LIMITING
>PROCESS on sustained (steady state) human population?

I disagree with the notion of no new technology, and also with the
importance of limiting ourselves to 10% extinction.  I believe we could
go to 95%, the level of the Permean extinctions, without major impact
on our civilization.  However, even asssuming the 10% it is a
straightforward matter, if it was that important to us, to find,
catalog, and store for safekeeping all the remaining undiscovered genome
on this planet, within 20 years, for a few billion dollars per year.

>Any takers? What limits human population with land use, and
>technology fixed at current levels, and affluence at the high end of
>existing societies' conditions?

The premise of the question limits us.  :-)  Seriously, if we fixed tech
at present levels, the affluence would go nowhere but down, and land use
for anything but masses of poverty-stricken humans would be out of the
question.  We still might save those species genetically, at least if
you give us some _minor_ tech modifications for the search & rescue mission,
but we would never be able to revive the habitats in a future
underground-hab surface-nature-park Earth or in a space colony.

>Then the question of where to put them arises. If they all live a Connecticut
>lifestyle, their endless suburbs will take up a lot of room. Since we
>specified no loss of wildlands, a tradeoff occurs.

But it is possible to trade suburbs for cities, yard-and-house for
high-rise-condo, suburbian spread-out-mall to urban high-rise mall,
etc. We could go quite a ways with this. (We could go much further
yet with new tech like multi-story manufactured homes, cheap underground
excavation and construction, etc. but you set the rules... :-)

Also, it is possible to trade off low-biodiversity habitat (eg deserts,
tundra, etc.) for high-biodiversity habitat (wetlands, rain forests,
etc.)  Our current environmental policies are nearly 180 degrees
backwards in this regard.  

>If, however, you don't give a damn about wilderness, and believe life
>is sustainable without it, then 50,000,000,000 is probably sustainable
>at current technology levels as far as land goes, and then you need to
>check on water supplies. 

We're never going to get anywhere near 50 billion, alas.  Demographic
trend turns over to negative population growth at 10-15 billion, with
no known way to stop it.  

Water is dependent on macroengineering, which the ecofascists fight at every
turn (eg here in Portland they have blocked the tapping of the Columbia
for years, leading to big shortages in a place reknowned for its wet
climate).  If we all had $3/barrel oil like Saudi Arabia, or the 
nuclear-power equivalent (which is possible with some new tech and 
removing most of the useless regulations), we could desalinize the ocean 
and easily support 50 billion.  And save all those species in the
bargain.


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