Perplexed in Peoria  wrote or quoted:
> "Tim Tyler"  wrote in message
news:ceqv55$2rjd$1{at}darwin.ediacara.org...
> > Jim Menegay  wrote or quoted:

> > > By "maximum potential of the Earth", do you mean
the maximum sustainable
> > > human population?  My guess would be 1-2 billion people, though others
> > > are less pessimistic.
> > >
> > > But, I have to ask, why do you wish to actually achieve the maximum?
> > > What is lost if we were to "run" the earth a
little less close to
> > > the "red line" and only support half of the
absolute maximum possible
> > > population of humans?
> >
> > Questions about how many humans the planet can sustain for extended
> > periods are difficult to answer.
> >
> > n_Growth.htm
> > ...has the world's population rising to around 10 billion people by
> > 2150 and then levelling off - but 146 years is a long time, and
> > predictions on that sort of scale are necessarily quite speculative.
> >
> > I suspect that this graph represents an under-estimate - and that
> > substantial population growth will continue on the planet long after
> > that point.
> 
> Oh, I don't doubt that, purely in biological terms, the earth can provide
> food for as many as 20 billion people or more, and sustain this level
> for millenia. [...]

By which time, our gravity well will probably be seen as a trivial
barrier, our ecosystem will have graduated from this planet - and
we'll have far more than our planet's resources at our disposal ;-)

> My lower figure of 1-2 billion was based more on sustainable use of other
> kinds of resources - particularly energy.  We can't support large populations
> at current levels of energy consumption using fossil fuels.  Fissionables
> give us only a few more millenia.  Fusion may be our ace in the hole, for
> energy, but then there are other resources that we are currently consuming
> unsustainably.

We have a huge Sun right nearby.  And there's lots of matter around,
E=mc^2 - and "c" is pretty big.  I can't see energy being much of a 
limiting factor for a very long time to come.

> Groundwater, for one.  It is not clear that we must inevitably poison 
> the land that we use for agriculture, but it is clear that we are doing 
> so now.  This obviously can't continue for too many millenia.

There's a lot of water in the oceans.  I don't forsee serious water
shortages for quite a while either.

If the water is mucky, the usual approach is purification - and we
do plenty of that today.

> > The planet supporting large numbers of people /is/ important.  Humanity
> > is part of a race - and its long-term success may depend critically on
> > its rate of development.  While over-population won't do us much good,
> > under-population is to be avoided as well - since a smaller number of
> > scientists, engineers, and technologists will slow down progress - and
> > may eventually result in increased probabilty of our extinction due
> > to our lacking the technology needed to face challenges.
> 
> I agree that the pace of cultural and technological advance depends upon
> population.  My counter argument might be that the most rapid progress
> comes when we have scientists and engineers with time on their hands.
> If all of our scientific and engineering talent is focused on "keeping
> the machine running at the red line" [...]

We are certainly agreed that pushing the population envelope as far as
we can might not be the smartest thing to try.

> Besides, the timeframe that was originally mentioned was on the order of
> a billion years.  I think that even if we had only a few thousand scientists
> and engineers per generation, we would still make considerable progress
> in that kind of timeframe.

Probably - but by that time, aliens might have wiped us out.

I'm not kidding about those aliens.

Just because they are not banging on our door just yet doesn't
mean we can act as though they are not there - and if they *are*
there, we are likely to wind up in competition with them - and
in that case, dawdling around with "a few thousand scientists and 
engineers" might not be such a good move.
-- 
__________
 |im |yler  http://timtyler.org/  tim{at}tt1lock.org  Remove lock to reply.
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