I have a relatively minor point, in the present context, about forests
and carbon balance, but I feel compelled to make it. I also address
some of the larger issues below.
On 7/4/07, Don Libby <[EMAIL PROTECTED]> wrote:
...
> As evidence of overpopulation, Rapley cites a
> World Wildlife Fund figure of "1.25 earths needed to sustain the
> population", which is down from 5 earths just a few short years ago. If we
> carefully examine what goes into this number, we find that what it means is
> there are not enough forests to absorb carbon dioxide at a rate that would
> balance the rate of emissions.
While I don't know what goes into the calculation (and would like to
know), your analysis about forests is incorrect.
A mature natural forest at equilibrium is neither a net source nor a
net sink of carbon, almost directly by definition of "mature".
A growing forest is a sink.
A forest being cleared or shrinking back under assault from invasive
vermin is a source, of course.
A harvested forest used for paper products could conceivably be a sink
provided we eschew recycling and sequester the paper, a point which
rarely garners esteem from self-identified "environmentalists", but as
far as I know nobody is considering this, as it is probably
impractical from other points of view.
Forests may have other sustainability advantages, but my main point is
they don't sustainably constitute a net carbon flux.
> The overuse of coal relative to uranium is a
> very different problem requiring different solutions than the
> "overpopulation of the planet", yet careless thinking has led the former to
> be twisted around into the latter.
Indeed.
> The danger of this carelessness is further confusion and delay in attacking
> the serious problems of our day, such as overcrowding, poverty, disease
> pandemics, the rate of carbon emissions, and the rate of biodiversity loss.
> It is tempting to believe that all these problems would be reduced if only
> the global population were reduced, but population reduction as a goal has
> historically brought about the most inhumane treatment of humanity.
Nevertheless, the question of what the maximum population that can be
sustained indefinitely actually is remains a real one. We may not know
how to do something and still need to do it.
> The global population is currently stabilizing, carbon emissions are not.
I still think it is worth considering what the goal should be.
Regardless of the actual number, in the very long run the only
sustainable global fertility is the one that exactly balances
mortality (and in the unlikely event that space travel ever becomes
important in this matter, net emigration)
> Therefore we must look to other causes of carbon emissions to deal with them
> effectively.
I agree that this is far the more urgent problem. However, I would
like to see the sustainability issue addressed quantitatively. The
fact that in the long term any population growth rate other than
exactly zero is necessary in the very long run may not need to be
embedded in the culture anytime soon, but it's still true and
interesting.
I am very puzzled about the tight correlation between income and
fertility. We may be relying on it too heavily if we don't understand
it. At my current level of understanding it strikes me as possible
that cause and effect have been reversed. If so, it reminds me of my
plan to plant palm trees in Wisconsin to make the winters less harsh.
Don, or somebody, please reassure me that the causality is understood
if you can.
mt
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