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WORLDWIDE
FOREST/BIODIVERSITY CAMPAIGN NEWS
Earth
Needs 10 Million Years to Recover from Extinction
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Forest Networking a Project of Forests.org
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Conservation Archives
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Conservation
3/10/00
OVERVIEW
& COMMENTARY
The
"lag" between extinction and revival of comparable levels of
biodiversity
appears to be longer than thought.
Reestablishment of
species
diversity following a mass extinction, and the reconstitution
of
intricate ecosystems, may take up to 10 million years. Best
scientific
estimates are that, barring policy changes, half of the
World's
species will be lost in the next 50 to 100 years. The
current
cataclysmic loss of species diversity, and their emergent
ecological
patterns and processes, are not likely to be undone in the
lifetime
of the human species.
g.b.
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RELAYED
TEXT STARTS HERE:
Title: Earth Needs 10 Mln Yrs to Recover from
Extinction
Source: Reuters
Status: Copyright 2000, contact source for
permission to reprint
Date: March 9, 2000
SAN
FRANCISCO, March 9 (Reuters) - It takes the Earth about 10 million
years
to recover from the mass extinction of plant or animal species -
- far
longer than previously thought, two scientists reported on
Thursday.
And it
takes the environment just as long to recover from the
extinction
of even a few species, small events which nevertheless rip
holes
in the biosphere that are impossible ever to fully repair.
"When
you lose a species, that exact species is never coming back. You
can't
recreate an animal .... extinction is final that way,"
paleontologist
Anne Weil, a research associate in the Department of
Biological
Anthropology and Anatomy at Duke University, said .
"What
we were looking for is the point at which entire ecosystems
recover.
The baseline is an average of 10 million years."
The
study by Weil and James Kirchner, an environmental scientist at
the
University of California-Berkeley, comes amid predictions that as
much as
half of all the Earth's species could vanish over the next 50
to 100
years.
Kirchner
said the study results, published in the current issue of
Nature,
underlined the fact that humanity itself would be extinct
before
anything resembling any of the vanishing species is ever seen
again
on Earth.
"If
we deplete Earth's biological diversity, we will leave a
biologically
impoverished planet, not only for our children and our
children's
children, but for all the children of our species that
there
will ever be," he said.
The two
scientists arrived at their findings by comparing the
extinction
rate of fossil marine organisms with their rate of
evolution,
or "origination," over 530 million years.
Looking
at some five major extinction events, like the one that killed
the
dinosaurs 65 million years ago, as well as smaller die-offs, they
concluded
that the "lag" between extinction and revival of
biodiversity
was much longer than had previously been believed, and
was
remarkably consistent.
"This
is a very exciting finding. What we found is a previously
unrecognized
pattern in the fossil record," Weil said. "The lag is
evidence
of an evolutionary dynamic which wasn't suspected before, and
which
we don't yet fully understand."
Kirchner
stressed that their sobering findings do not necessarily mean
that
the multitude of plants and animals currently endangered by human
activity
are necessarily doomed for ever.
"It's
cause for concern, and it's a cause for caution, but its not a
cause
for depression," Kirchner said. "It is not preordained. Whether
it
happens depends on the choices we make....We can chose not to let
it
happen."
But he
added that the speed with which fragile environments are being
overrun
meant the choice would have to be made soon. Many species, in
fact,
are disappearing from the Earth before human scientists can even
catalogue
them, he said.
"It
has been likened to burning down the library when you don't know
how
many books are there, let alone what's written in them," he said.
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