/* ---------- "Economist vs Biologists on Extinct" ---------- */
Economist vs Biologists on Extinction
[The following sequence of articles and letters appeared in the
New York Times and the San Francisco Chronicle last May. Julian
Simon, a direct-mail marketing expert, and political scientist
Aaron Wildavsky started the "debate" by claiming they have
"documentation" which proves that biologists are wrong about the
human-caused mass extinction that is occurring throughout the
biosphere. Their article follows. Five scientists replied in
further articles and letters reproduced below. -- Alan McGowen]
[From the New York Times, May 13, 1993.]
Facts, Not Species, Are Periled
By Julian L. Simon
and Aaron Wildavsky
(Julian Simon is professor of business at the University of
Maryland, Aaron Wildavsky is professor of political science at
the University of California.)
Oakland, Calif.
If President Clinton signs the Rio accord to protect rare and
endangered species, he will place scientific truth in greater
danger than endangered species.
A fair reading of the available data suggests a rate of
extinction not even one-thousandth as great as doomsayers claim.
If the rate were any lower, evolution itself would need to be
questioned.
The World Wildlife Fund, the main promulgator of alarm about
biodiversity and and the extinction of species, frames the issues
in the starkest terms: "Without firing a shot, we may kill one-
fifth of all species of life on this planet in the next 10
years." This assertion is utterly without scientific underpinning
and runs counter to all the existing evidence.
Such apocalyptic claims are used to bludgeon the Federal
Government for money and action. A long-running fund-raising
pitch from World Wildlife Fund's president, Russell E. Train,
describes how the organization rallied support for
reauthorization of the Endangered Species Act by telling Congress
that "up to one million species of life will become extinct by
the end of this century" unless governments "do something."
Mr. Train added: "When we talk about the loss of one million
species, we are talking about a global loss with consequences
that science can scarcely begin to predict. The future of the
world could be altered drastically if we allow a million species
to disappear by the year 2000."
The warning is amplified by the media. The Washington Post quoted
the claim of a top Smithsonian conservation biologist, Thomas
Lovejoy, that "a potential transformation of the planet unequaled
perhaps since the disappearance of the dinosaur" is about to
occur. The Post also cited Harvard University's Edward O. Wilson,
a biologist, on "the folly our descendants are least likely to
forgive us." The emotions behind such sweeping statements cause
partisans to believe that the matter is too important to be
subjected to the standards of normal science.
Recommendations that leading biologists and ecologist[s] base on
non-facts are staggering. Professor Wilson and Stanford
University's Paul Ehrlich, a biologist, actually ask that
governments "reduce the scale of human activities." They want us
to cease `developing' any more relatively undisturbed land"
because "every new shopping center built in the California
chaparral... every swamp converted into a rice paddy or shrimp
farm means less biodiversity."
The standard source of all the apocalyptic forecasts is a 1979
book, "The Sinking Ark," by a conservation biologist, Norman
Myers. Mr. Myers's work rests on two statistics: the estimated
extinction rate of known species of animals between the years
1600 and 1900 (about one every four years) and the estimated rate
from 1900 to the present (about one a year).
Mr. Myers abruptly departs from those modest estimates and goes
on to say that some scientists have "hazarded a guess" that the
extinction rate "could now have reached" 100 species a year. This
pure conjecture about an upper limit of present extinction of
species is then increased and used by Mr. Myers and Mr. Lovejoy
as the basis for the projections quoted elsewhere.
In fact, Dr. Lovejoy -- after converting an estimated upper limit
into a simple estimate -- says that Government inaction is
"likely to lead" to the extinction of 14 to 20 percent of all
species before the year 2000.
Dr. Lovejoy's extinction rate, which is a thousand times greater
than the observed rate, is pure guesswork. Yet it is widely
published and erroneously viewed as scientific fact.
In articles in the mid-1990's [sic] in New Scientist magazine, in
newspapers, in books and at conferences, both of us have
documented the complete absence of evidence for the claim that
the extinction of species is going up rapidly -- or even going up
at all.
No one has disputed our documentation. Nor has anyone cited new
evidence that would demonstrate rapid extinction. Instead, until
recently, the biologists sounding the alarm simply ignored the
data that challenged their claims.
But recently the World Conservation Union published an inquiry
into the extent of extinctions, "Tropical Deforestation and
Species Extinction." Every author included agreed that the rate
of known extinctions has been and continues to be very low. One
wrote, "Forests of the Eastern United States were reduced over
two centuries to fragments totaling 1-2 percent of their original
extent... During this destruction, only three forest birds went
extinct."
We are delighted that this species of truth, which we thought was
dead, is stirring into life.
President Clinton should heed this astonishing scientific
assessment. We are not suggesting that he ignore the possible
dangers to species. But everyone should start from an unbiased
view of the gains and losses in order to help judge how much time
and money to spend guarding our biological assets.
*****************************************************************
[Paul Ehrlich replied in the May 21, 1993 San Francisco
Chronicle.]
Species' Count Tied to Environment Loss
(Paul R. Ehrlich is Bing Professor of Population Studies and
president of the Center for Conservation Biology at Stanford
University.)
Are the world's ecologists and evolutionary biologists fleeing
from science and creating needless worry? Hardly.
It is true that no one is sure how much diversity there is,
however defined. Estimates of the number of species range upward
to 100 million, and there may be billions of genetically distinct
populations.
Also, no one is certain of the total number of current
extinctions, although accelerating rates of extinction in groups
as diverse as North American fishes and Hawaiian birds have been
abundantly documented.
At the same time, it is readily apparent that the overall loss of
biodiversity is accelerating.
Biologists know that extinction rates are directly related to
rates of habitat loss because all organisms are adapted to
specific habitats and many, if not most, have narrow habitat
requirements.
Data from a wide variety of sources, but especially from studies
of the disappearance of species from newly isolated islands of
habitat, show that for any reduction in area of 90%, the number
of species is roughly halved.
While some dispute the connection between extinction rate and
habitat loss by citing the fact that "only" three forest birds
went extinct during the destruction of the Eastern United States,
it must be pointed out that that deforestation was only
transitory.
Clearing peaked around 1900, and regrowth had occurred by the
middle of this century. If the maximum clearing had been
permanent, half or more of the bird species would have gone
extinct.
Also, the history of the Eastern forests speaks not at all to the
extinctions caused by permanent forest clearing, not even in
temperate zones, let alone the tropics where far more diversity
is crammed into smaller areas and forest recovery is more
problematic.
Furthermore, population extinctions can threaten our "biological
assets," even if species diversity is not diminished. If each wild
species was reduced to a single viable population and those
populations were saved in nature preserves, zoos, and botanical
gardens, their esthetic values would be largely devastated.
Birdsong no longer would enliven suburban neighborhoods in the
spring, and wildflowers no longer would beautify landscapes.
There also would be the potential for economic loss because
genetic variability is crucial to the development of crops and
the discovery of medicines.
Societies also might not survive the loss of populations of other
organisms. Many are key to providing and maintaining essential
ecosystem services, such as maintaining the proper mix of
atmospheric gases and moderating the climate.
No shred of evidence has ever been produced to indicate that the
extinction of species is not going up rapidly. Indeed, any person
who understands the connection between habitat destruction and
extinctions can see plainly that the rate of both is increasing.
******************************************************************
[Four scientists replied to the Simon and Wildavsky article in
the May 25, 1993 issue of the New York Times, in letters to the
editor. David Wilcove and Michael Bean are respectively senior
ecologist and chairman of the wildlife program of the
Environmental Defense Fund. Norman Myers, whose book _The Sinking
Ark_ Simon and Wildavsky claimed "the standard source of the
apocalyptic forecasts" is a visiting fellow at Green College,
Oxford University and senior fellow with World Wildlife Fund --
US. Edward O Wilson is Baird Professor of Science at Harvard
University and has won two Pulitzer prizes for his many books,
which include the controversial works _Sociobiology_ and _On
Human Nature_. His most recent book is _The Diversity of Life_.]
[David Wilcove and Michael Bean reply.]
Before Skies Become Entirely Barren of Birds
To the Editor:
Julian Simon and Aaron Wildavsky in "Facts, Not Species, Are
Periled" (Op-Ed, May 13) believe scientists are being
unscientific when they warn of an impending tidal wave of
extinction of animal species caused by humans. They claim, "both
of us have documented the complete absence of evidence for the
claim that the extinction of species is going up rapidly -- or
even going up at all."
Wrong. Dead wrong. Consider first the data on fishes. According
to a 1989 report from the American Fisheries Society, 40 species
and subspecies of North American fishes have vanished in this
century. Thirteen became extinct between 1900 and 1950, and 27
have disappeared since 1950 -- a doubling of the rate over this
century.
But the bigger issue is not how many species have become extinct,
but how many are likely to vanish if trends continue and whether
or not the trends are worsening. Consider the best studied
animals in the United States, birds. Whe Interior Department
compiled the first official list of endangered animals in the
United States in 1967, it listed 36 birds. Since then, the tally
of threatened and endangered birds in the United States has more
than doubled to 90. Most of the additions come because of
population declines and threats that have occurred since 1967.
Mr. Simon and Mr. Wildavsky may not spend much time outdoors, but
we can assure them that each year the spring migration becomes
less colorful and less musical -- an impression confirmed by bird
counts from the Fish and Wildlife Service. Must we wait until the
roster of extinct species has grown so that the loses are
apparent even to office-bound skeptics before sounding an alarm?
We can quibble about numbers -- the ecological equivalent of
fiddling while Rome burns -- or try to prevent this irreversible
and senseless loss.
David Wilcove, Michael Bean
Washington, May 14, 1993
[Norman Myers replies.]
What Data?
To the Editor:
In "Facts, Not Species, Are Periled" (Op-Ed, May 13), Julian
Simon and Aaron Wildavsky state that the "standard source of all
the apocalyptic forecasts" of mass extinction of species is "a
1979 book, `The Sinking Ark,' by a conservation biologist, Norman
Myers."
Since writing this book, I have published several dozen papers in
scientific journals and three further books that clarify and
substantiate my 1979 assertions -- except that these further
writings demonstrate that the extinction rate is not 100 species
a year but more like 50 to 150 species a day. This finding has
been confirmed by independent analyses by other leading
biologists, such as Professor Edward O. Wilson of Harvard.
I have drawn Julian Simon's attention to my additional appraisals
in two face-to-face debates with him in Washington and New York,
the last just a few months ago.
I have sent him copies of many of my papers, including two
extended chapters for a version of the New York debate that is
yet to be published, presenting abundant documentation. Yet he
persistently ignores my further findings, as well as those of
other extinction experts.
Mr. Simon and Mr. Wildavsky further assert they "have documented
the complete absence of evidence for the claim that the
extinction of species is going up rapidly -- or even going up at
all." And: "No one has disputed our documentation." What
documentation? I have repeatedly challenged them to adduce their
documentation; zero response.
They continue, "Nor has anyone cited new evidence that would
demonstrate rapid extinction." They could run a literature check
on a library computer and find listings of hundreds of papers and
books with specific and detailed data. Yet they object that
"biologists simply ignored the data that challenge their claims."
Again, what data?
Their article offers lots of complaints, and nothing more, though
they criticize biologists for lack of "scientific fact."
Norman Myers
Oxford, England, May 14 1993
[Edward O. Wilson replies.]
Mass Extinctions Grow
To the Editor:
Julian L. Simon and Aaron Wildavsky (Op-Ed, May 13) state that
biologists have greatly exaggerated the extent of species
extinction. "No one has disputed our documentation," they say. I
do so now. They have no documentation. Moreover they ignore the
mass of data that accumulates from one month to the next, in
monographs and scientific journals devoted to biodiversity.
All biologists know that as habitat is reduced, species go
extinct. The rate of loss, established by hundreds of independent
studies on many kinds of plants and animals, has been found in
the great majority of cases to fall between the third and sixth
root of the area. The estimated rate of loss of tropical rain
forest in the 1980's for example, translates at a typical value
(the fourth root) to .5 percent species lost or doomed per year.
The observed loss of bird species locally in tropical American
rain forest patches reduced to 1 to 25 square kilometers has been
observed to reach 10 percent to 50 percent in the first 100
years. Pollution and the introduction of exotic species drive the
rate still higher, and extinction approaches totality as the last
of the habitat is erased.
Mass extinctions of this magnitude are being observed more
frequently around the world, in groups as different as freshwater
fishes and flowering plants, and they often entail the total
extinction of species and races found nowhere else. It is a sad
rule of field biology that when ecosystems are studied carefully
before and after serious human disturbance, species extinctions
are almost always revealed.
Edward O. Wilson
Baird Professor of Science
Harvard University
Cambridge, Mass., May 13, 1993
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