Earth's Carrying Capacity

Ian Stirling wrote in message ...
In sci.space.policy Al Jackson wrote:
Gactimus wrote in message ...
How many people can the earth support?

Assume exponential growth.
If you assume all humans stay on earth and imagine that there is a
'super science' of progress
solving all social, political, economic and logistics problems. Then
in an article in:

"Population, Evolution, and Birth Control, A Collage of Controversial
Ideas, Ed. Garret Hardin; W.H. Freeman, 1964, ISBN 0716706709, (381p).
"

(I don't have my copy at hand.)

I believe the upper limit is roughly 20 people per square meter! Or
about 2E15 people! The reason for this limit is that the earth would
consist of a single metal sphere and which would start
to melt due to the inability of the sphere to radiate all combined
body heat (by black body radiation) of that many people. This happens

This isn't quite the limit.
2E15 people, assuming 500w of heat produced by the person, and their
food production.

This is 10^18W

Total solar insolation (at the outside of the atmosphere) is some
2*10^17W.

If global temp average is now some 285K, then to increase heat emission
by a factor of 5, you need to increase the surface temperature to
427K.

To move the heat from a habitat at 300K, you need refrigeration, which
will need more power, but that'll only increase the surface temperature
to perhaps 460K.
You can probably get another factor of 10 this way, with the
surface glowing a dull red, and lots of external energy.

You'd be barking mad to though, IMO the point at which it makes no sense
to even consider more development on earth would be where, with a sunshield
to eliminate IR and reduce visible a bit, global temperatures are some
10C higher on average than now.

The artice is by J.H. Fremlin, "How Many People
Can the World Support?," New Scientist 415 (1964): 285-7.
I missed it, he gets 120 people per square meter.
I also missed the time, takes only about 900 years!
Article was republished in,

"Population, Evolution, and Birth Control, A Collage of Controversial
Ideas, Ed. Garret Hardin;

Can read the physics involved there.

"Ian Stirling" wrote ...
Well, for example to make salination irrelevant, you can go to desalinated
water to irrigate.
It's expensive, but technically possible.

Drainage improvements. If your water is going out as liquid water with
the dissolved salts then salination is less of a danger than if it hangs around
until it goes as vapour with the salts left behind/massive simplification.

Ian Stirling wrote in news:4121ff6c$0$89457
:

Biosphere II was a deeply stupid experiment by people who valued the
statement over the science.
The right way to do this kind of thing is not to make hugely complex
systems that you can't hope to accurately analyse, but "feel" right, but
to proceed from simple systems that you can completely analyse up.

There is no right way in science. Sometimes you it pays to do "stupid"
experiments just to see what happens. It may not have been a very cost
efficient project when it comes to scientific output vs cost, but then I
think it was funded privately.

"Thomas Palm" wrote ...
Ian Stirling wrote
Biosphere II was a deeply stupid experiment by people who valued the
statement over the science.
The right way to do this kind of thing is not to make hugely complex
systems that you can't hope to accurately analyse, but "feel" right, but
to proceed from simple systems that you can completely analyse up.

There is no right way in science.

Even if there is no /one/ right way in science there are any number of wrong
ways.

Sometimes you it pays to do "stupid" experiments just to see what happens.

Often it pays to do experiments where you don't have a guess as to what the
result will be or whether the result will have any practical use or not.

There are, however, types of 'experiment' which, when done, leave you
wondering what the heck it is you proved / disproved (if anything) other
than some people'll fund anything.

It may not have been a very cost
efficient project when it comes to scientific output vs cost, but then I
think it was funded privately.

Not so long ago in rec.arts.sf.written, Peter Bruells wrote:
Well, it's probably not really feasible to "farm" fish in the
conventional matter. Kinda hard to put a brand on a hering. But we do
try to restock the wild fish.

Here's one route towards that end
http://www.wired.com/wired/archive/12.05/fish.html

"roaming robots that bring fish farming to the open seas"

--
Joe Morris
Live music in Atlanta http://jolomo.net/atlanta/shows.html

Not so long ago in rec.arts.sf.written, Jim Logajan wrote:
"Jim Oberg" wrote:
"Gactimus" wrote in message
...
How many people can the earth support?

We could, all of us, stand on Zanzibar.

Who would be the last to stand on Zanzibar?

The guy who was supposed to bring the beer

--
Joe Morris
Live music in Atlanta http://jolomo.net/atlanta/shows.html

In article ,
Pete Lynn wrote:
...The current birth rate
is low and is likely to stay that way, because in an advanced
society, children are a major economic burden on the parents.
Given control over the biology (i.e., contraception), that trumps
biological "imperatives".

A reduction in unwanted pregnancies will eventually be compensated for
by an increase in wanted pregnancies.

Why? *Both* numbers have been declining for a long time. Why should one
of them turn around?

Contraception is used to control the timing of having children, but it's
also used to *prevent* having children (or to prevent having *more*
children), and that's an outright reduction, not a shifting of the
wanted/unwanted balance.

Contraception will not lower birth rate in the long term...

It *does* lower birth rate in the long term. (Effective contraception has
been available in the industrialized countries for a couple of centuries
now; the condom was an 18th-century invention, if I recall correctly.)

...Some among us can independently sustain high birth rates
at first world levels. For example the Mormons. Given time, such
populations might be expected to take over.

Other things being equal, you might expect that. But other things
*aren't* equal. Even religions are subject to natural selection; ones
which tend to impoverish their believers, without compensating benefits,
don't last well.

Bear in mind that many organized religions are still grappling with the
20th-century transition of Western society from a population dominated by
farmers to one dominated by urban employees. On a *farm*, kids are an
economic asset.

While I expect birth rates to remain low for the next few generations,
in the long term I expect cultural adaptations that again increase birth
rate.

On what basis do you expect such a counterproductive change?

Human evolution might be currently flummoxed, but it will find its
bearings, and the human race will again get serious...

The human race is now evolving via its brains rather than its gonads.
Biology is no longer in control, and is unlikely to make a comeback.
Evolution is not "flummoxed", it is proceeding more rapidly than ever,
but in a different arena.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In sci.space.policy Thomas Palm wrote:
Ian Stirling wrote in news:4121ff6c$0$89457
:

Biosphere II was a deeply stupid experiment by people who valued the
statement over the science.
The right way to do this kind of thing is not to make hugely complex
systems that you can't hope to accurately analyse, but "feel" right, but
to proceed from simple systems that you can completely analyse up.

There is no right way in science. Sometimes you it pays to do "stupid"
experiments just to see what happens. It may not have been a very cost
efficient project when it comes to scientific output vs cost, but then I
think it was funded privately.

My basic problem is that it diddn't have a clear possible result.

At best, almost the only question it can answer is "what happened".

You can make no good predictions on what would happen if you
change X or Y.

They can't answer what would happen if you changed the size of the
enviroments, as they don't adequately know the role of everything,
not to mention all the interactions.

(Henry Spencer) wrote in
:

In article ,
Pete Lynn wrote:

Contraception is used to control the timing of having children, but
it's also used to *prevent* having children (or to prevent having
*more* children), and that's an outright reduction, not a shifting of
the wanted/unwanted balance.
Contraception will not lower birth rate in the long term...

It *does* lower birth rate in the long term. (Effective contraception
has been available in the industrialized countries for a couple of
centuries now; the condom was an 18th-century invention, if I recall
correctly.)

This is not long term from an evolutionary perspective. Some people have a
genetic tendency to want more children and they will not want to use
contraceptives. What is to stop their genes to spread throughout the gene
pool? It will take many generations, but in a society where just about
everyone survives to reproductive age the primary trait selected for is the
ability and intention of having many babies.

Read "The Mote in God's Eye" by Niven and Pournelle for a depressing view
on what might happen if this reproductive evolution has time to take
control.

The human race is now evolving via its brains rather than its gonads.
Biology is no longer in control, and is unlikely to make a comeback.

Don't underestimate biology! For a long time doctors did, and watch where
that got us in term of multi-resistent diseases that are harder to kill
than ever before. We may not like to admit how much biology control our
behabior, but it does.

On Tue, 17 Aug 2004 13:41:53 GMT, Thomas Palm
wrote:

Biosphere II was a deeply stupid experiment by people who valued the
statement over the science.
The right way to do this kind of thing is not to make hugely complex
systems that you can't hope to accurately analyse, but "feel" right, but
to proceed from simple systems that you can completely analyse up.

There is no right way in science. Sometimes you it pays to do "stupid"
experiments just to see what happens. It may not have been a very cost
efficient project when it comes to scientific output vs cost, but then I
think it was funded privately.

It was done as a conceit, that ecology is so well known that there
would be no particular problems.

Paragon corporation claimed they wanted to study how to minimize
ecologies to fit on spacecraft for interplanetary exploration and
colonizations. They would then sell what they learned to governments
as consultants to expeditions.

Unfortunately, a different lesson was learned by them, and not learned
by the public. That lesson is:

"Ecology is current insufficiently understood by the best of the human
race".

Learn that lesson. Much greater investment needs to be poured into the
biological sciences. It is premature to believe that humans
sufficiently understand their planetary life-support systems. Toss the
conceit and adopt the proper humility.

Do the LEARNING FIRST before doing planetary re-engineering.