Humans are a part of (and, as most here believe, a
> product of) nature, therefore environmental destruction (or you may call
> it alteration) caused by our activities is natural.
Scenario: We've developed nuclear weapons in the world..... Is it "natural"
if we choose blow up the entire world? How will it rebound from complete
destruction?
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If a few representative species survived (maintaining disparity), then the
history of mass extinctions in the geologic past suggests that the earth's
biota would recover a good portion of its diversity within several to
several tens of millions of years. . .
The worst mass extinction occurred-in-the end of the Permian Period, just
before the arrival of the dinosaurs. Approximately 90% of the marine
diversity was eliminated, and in the aftermath the marine environment of the
Early Triassic Period was overwhelmingly dominated by snails and bacteria.
That is the worst the earth has experienced so far (since the appearance of
multi-cellular critters about 700 m.y. ago), and the recovery was quite good
after several million years, but that is a long time to find nothing but
snails and slime.
I like to make this point in classes: The earth has been around for 4.5
billion years and has seen its share of disasters. The earth will definitely
survive, and life will go on--even if it has to start over from bacteria
(and more than that would survive mere nuclear holocaust), but it takes a
very long time to re-evolve a global ecosystem--meanwhile, you gotta
survive.
What is in danger is the ecosystem that gave birth to our species and that
continues to support us.
At some point, long before we completely destroy the ability of this planet
to support ANY life, we may destroy its ability to maintain human life. At
that point the problem will be solved, and life will recover. Personally I
think we have been working toward this goal since the extinction of Mammoths
(but some will still debate the human role in THAT).
It is interesting to note that in historical geology and paleontology texts,
oxygen is listed as the first "pollutant" in that the bacteria that produced
it were not equipped to live in it or utilize it. By filling the atmosphere
with it, they forced themselves and their companion species into marginal
niches, while opening the world up for a completely different set of life
forms.
Anyway, just the perspective of a paleontologist . . .
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