Geology Reference
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pelled me into a deep experience of Gaia's living biodiversity. My body tingled with a
sense of the trillions of organisms teeming over the animate Earth, each contributing in
its own small way to the movements of vast quantities of chemical beings in and out of
the air, the rocks and the waters of our living planet. Once again, for a few brief mo-
ments I had been Gaia'ed . I had experienced biodiversity as a powerful force that keeps
our planet alive.
Biodiversity is the diversity of life at various levels of organisation, ranging from
genes, species, ecosystems, biomes and landscapes. As far as we can tell, the Earth just
before the appearance of modern humans was the most biodiverse it has ever been dur-
ing the 3,500 million years of life's tenure on this planet, and before we began to upset
things the Earth hosted a total of somewhere between 10 and 100 million species. The
fossil record shows us that there have been five mass extinctions in the last 400 million
years or so, all due to natural causes such as meteorite impacts, flood basalt events, or
possibly because of drastic internal reorganisations within biotic communities; but the
greatest and fastest mass extinction is happening now, and is entirely due to the eco-
nomic activities of modern industrial societies. We are haemorrhaging species at a rate
up to 1,000 times the natural rate of extinction, or, more prosaically, every day we are
losing 100 species, mostly in the great tropical forests because of our endless desire for
petroleum, timber, soya, palm oil and beef. Coral reefs and the marine realm in gener-
al are not exempt from our destructive attentions either. The list of atrocities which our
culture has perpetrated on the living world makes for chilling reading. According to E.
O. Wilson and Paul Erlich, two of the most eminent ecologists of our day, a quarter of
all the organisms on the Earth could be eliminated in 50 years. By the end of the 20th
century, about 11% of all bird species, 18% of mammals, 7% of fish and 8% of all the
world's plants had been threatened with extinction. According to the Living Planet In-
dex, in the period from 1970-2000, forest species declined by 15%, fresh-water species
by a staggering 54%, and marine species by 35%.
Does the current mass extinction really matter? What does biodiversity do for Gaia,
and for us? To anyone who is deeply in touch with nature, it is absurd to ask these ques-
tions—clearly the current mass extinction is a crime of vast proportions. Our intuitions
and deep experiences of the more-than-human world tell us that biodiversity gives us
three key benefits that Aldo Leopold talked about: integrity, stability and beauty. But
what does science have to say about the importance of biodiversity? To explore this
question we need a systems diagram showing how biodiversity contributes to the well-
being of Gaia ( Figure 41 ).
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