NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/sci/environm/12927

Internet Message Format | 1992-11-21 | 9.1 KB

Path: sparky!uunet!olivea!sgigate!sgi!cdp!alanm
From: [e-mail] (Alan McGowen)
Newsgroups: sci.environment
Subject: Re: Habitat and economy (was: Ecocentri
Message-ID: <[e-mail]>
Date: 21 Nov 92 09:49:00 GMT
References: <[e-mail]>
Sender: Notesfile to Usenet Gateway <[e-mail]>
Lines: 165
Nf-ID: #R:[e-mail]:-357630725:cdp:1466601927:000:8823
Nf-From: cdp.UUCP!alanm    Nov 21 01:49:00 1992


The discussion Michael is trying to start is the same as the one
I have long been trying to start. With two of us trying, maybe
some discussion is now possible.

Michael:
>I'd appreciate if you could expand on this at your leisure, as I see
>many questions arising from the relationship between human comfort and
>adequate wildlife habitat. For instance:
>
>Firstly, I take it from this that you think the impact of the 4 billion
>at subsistence levels is less than the impact of the 1 billion in affluent
>nations.

Not exactly. The percapita impact of the billion in
affluent areas is maybe 10 times that of the very poorest billion
and something less, like 2-6 times, that of the rest. The net
effect is that the most affluent contribute a large fraction of
the whole impact, but probably not the largest fraction.

>Is this why you think that 2 billion affluent people would demand
>yet more land? I am not convinced of this. Do you have evidence?

The most affluent 1 billion *are* demanding continued habitat
conversion -- oil drilling in the Arctic, logging and mining in
tropical areas, and conversion necessitated by unsustainable
production of tropical-region crops such as coffee, tea, sugar
and tobacco. They also demand many other impacts: pesticides used
on Mexican crops for US consumption find their way into Mexican
food chains and some of them bioconcentrate. As affluence
increases in the poorer parts of the world, so do these demands.
However, local demands among the less affluent also contribute to
habitat destruction to a very important extent: the problem would
not go away if the most affluent dissappeared, it would just slow
down a bit -- and only for a while, as populations in many of
those areas soar.
>
>Secondly, you seem to agree with me that loss of habitat is the predominant
>problem. Is this true? Can you provide better evidence than I can?

From a short-term anthropocentric point of view, loss of habitat
is probably not a big problem -- this is the reason that so much
talk about shifting values is necessary. From an evolutionary
point of view, loss of habitat is overwelmingly the problem right
now -- but that could change. If rapid climate change, large and
lasting ozone depletion, or some unforeseen threshold in
bioconcentrated toxics becomes important, it could well become
the dominant extinction factor. I also have to mention that we
cannot rule out large scale faunal and floral collapses arising
from purely ecological effects of loss of diversity. The reality
is that we will probably be facing all of these insults
simultaneously. Yes, that might come to dominate habitat loss.
But right now, habitat loss is the main evolutionary threat.

>Thirdly, why are you so certain that affluence is so tightly tied to
>land demands? I suspect that many of the most damaging uses are of small
>economic value, the burning of the Amazon being an obvious example.

I guess I'm more cynical about what is of "economic value". I
think our best guide is not what we would wish, but what is
actually happening. The indications don't support the idea that
the most damaging uses are of little economic value -- the
extraordinary lengths to which poor people will go to carve out
a chunk of rainforest, or to gather a bit of firewood or some
water miles away from home, suggest to me that these are vital,
not little, economic needs. Reduction of the A factor of I=PAT is
the most problematic of all. It is clearly way too large in the
most affluent parts of the world, but for very many humans A is
too small. What we need to do is to rethink the whole set of
concepts underlying A, and find what is really the right value or
range of values of A for a human. I realize that this statement
is absolute heresy. But I think that there *is* a "right range of
values" -- it's the one which is coevolutionarily supportable, by
which I mean that humans can live with it, and the biosphere can
live with it (without even slow degredation) for as long as there
are humans -- maybe millions of years, if we can do that.

*This* is the discussion I would really like to start, at some
point.

>Fourthly, if currently available wilderness ceased

All of it? I think you don't appreciate the destruction that
would involve. Something like 2/3 - 3/4 of all species would be
lost outright if that happened. Not slowly, through deterioration
-- outright extinction. Then there would be fallout of consequent
extinctions elsewhere, probably following an inverse exponential
curve. This is the very nightmare scenario I painted in an
earlier post in which some 80% or more of all diversity is lost.
I'm not at all sure we could survive that -- and if we could, I'm
not sure we would want to. The outcome would be worse than the
worst nuclear war scenario -- after all, nuclear wars don't
target wildlands. Remember that the resulting degradation would
be irreversible.

Under those conditions we might well find that old friends like
wheat and corn and pigs behaved weirdly -- constantly got
unexplainably sick, grew poorly after a few generations, and were
attacked by plagues of formerly benign organisms -- and the same
could be true of us. Our prospects would be incredibly dismal in
that world -- it would be like trying to live without much of an
immune system. All that "useless" diversity is the world's immune
system, what it can use to absorb shocks and random fluctuations.
Human life without it might go on for a while, but there would be
no margin for error -- like living in a space colony.

>but efforts were made to
>trade scatterred and fragmented wilderness areas for large contiguous
>areas, would that suffice to stabilize the sitation if habitat loss were
>the only significant factor? (Clearly this depends on the
particular>
>ecological and economic uses of the land. What I'm asking for here is
>evidence that large scale reconversion of economic use to wilderness is
>necessary, as opposed to tradeoffs resulting in larger contiguous wild areas
>without major changes in total land usage.)

The value of restored lands or lands made contiguous is in their
potential to be recolonized by species in wild areas, or to
reestablish gene flow between disconnected populations -- in
other words their value arises from existing diversity, which it
must be our first priority to protect. There can be no "tradeoff"
between remaining wilderness areas an restored areas -- the
restoration is impossible without the centers of diversity to be
the seed sources. [And no, ex situ conservation in zoos or
cryogenic preservation is *not* sufficient, because it can't
maintain population genetic diversity and adaptedness, and it
only samples a tiny fractioneven  at the species level.]

I sense that you regard wildlife corridors as a kind of "magic
bullet" for all ills of population declines. They are popular
precisely because they are an inexpensive way to accomplish an
important step -- but we are deluding ourselves if we think that
the problem would dissappear after that step is taken. Eventually
we will have to face restoring areas that cut our economic bone
-- and that will only be tolerable if our population is
decreasing.

>Fifth and most important, can you suggest any ways to weigh the economic
>costs and ecological benefits of abandoning particular uses of land so
>as to most effectively restore stable habitat? In this context I'd like
>to point out that even though increasing human population almost certainly has
>a detrimental effect on habitat, it is less clear that decerasing population
>will automatically result in increasing wildlife habitat. I'd like to get
>away from intuitive value judgements and into finding a way to identify those
>land use conversions which would have a large positive impact on biodiversity
>while having a small negative impact on short-term economic value.

I can't address this now. Clearly you are right that any
reduction in population, generated any-which-way (e.g. nuclear
war) doesn't instantly translate into lots of restored ecosystem.
In fact one of the reasons I favor 500 million as the target
rather than the lower figures some advocate is precisely that
there would be centuries of restorative labor ahead of us -- and
you want the largest (supportable) workforce possible for that.
But I'm not sure that there is much point in trying to talk about
the right way to go about such a massive conversion in this forum
at this stage. I would just be drowned in screams of "Pol Pot!"
if I tried to do it.

This is undoubtedly not the detailed, quantitative, and
theoretically founded discussion Michael was hoping for -- but if
we keep at it, it could be a start in that direction.

------------
Alan McGowen