Rachel's Democracy & Health News #868  [Printer-friendly version]
August 16, 2006


[Rachel's introduction: "Species-area relationships lead to
projections of the loss of fully two-thirds of all species on Earth
by the end of this century.... And these projections do not include
the inevitably negative effects of climate change, widespread
pollution, and the destruction caused by alien species worldwide,
among other factors."]

By Peter Montague

Peter H. Raven, a well-known biologist, was president of the American
Association for the Advancement of Science (AAAS) during 2002. With 10
million members and affiliates, the AAAS is the largest scientific
organization in the U.S.; it publishes Science magazine.

Dr. Raven's presidential address to the academy in 2002 is a
succinct statement of where business as usual has carried us. In 2003,
Dr. Raven presented a companion paper to the Natural History Museum
in London, England. Here we summarize what he had to say in those two
papers. [I have added a few comments in the text, inside square
brackets. --P.M.]

[As you read through this description of the world we are handing to
our children, ask yourself, "If the environmental movement got
everything it is seeking, would it make a real difference in the
problems described here? Have we set our sights high enough? Have we
focused our minds on the real root causes?"]

Human Population

In 1950, the human population of Earth was 2.5 billion. A mere 50
years later it had grown to 6 billion. The human population is
expected to level off at 9 billion some time during this century.
[This will require 50% more of everything that we enjoy today -- 50%
more cities, hospitals, roads, parks, prisons, parking lots, trucks,
sewage treatment plants, farms and factories. If the human standard of
living rises during that time, even more will be needed.]

[How will things look when the human population has grown 50% larger?]

To support 6 billion people, each year we are dousing our crops with 3
million metric tonnes (6.6 billion pounds) of pesticidal chemicals
(1.1 billion pounds in the U.S. alone). Another byproduct of our
industrial agricultural system, Dr. Raven says, is that "We also are
poisoning the environment with the nitrogen we fix, our output now
exceeding the total derived from natural processes." [This deserves a
brief explanation: We "fix" nitrogen gas from the atmosphere, turning
it into a solid, and mix it into soils as fertilizer to stimulate
plant growth. Much of this nitrogen washes out of the soil and enters
streams, eventually reaching the oceans, where it stimulates growth of
algae, disrupting near-shore ecosystems with "red tides" and "brown
tides," and contributes to the death of corals, among other
disruptions. Humans are now putting more nitrogen into soils and water
than all non-human natural processes combined. By this measure we
humans are now more powerful than all the rest of nature -- quite an
astonishing accomplishment for a single species among the 10 million
(or more) species on earth.]

The Land

Human crops now require cultivated lands the size of South America.
"Most of the land used for agriculture and grazing, especially in the
tropics and subtropics, is being degraded by these activities and is
therefore becoming less sustainable and productive in the face of
increasing worldwide demand for high-quality food." Furthermore, "only
limited potential remains for expanding the area of land under

And, says Dr. Raven, "The rangelands on which some 180 million of us
graze 3.3 billion cattle, sheep, and goats occupy about a fifth of the
world's land surface; although there is a rapidly increasing demand
for animal protein, "in almost every case, the lands on which they are
being grazed are being progressively degraded to such an extent that
they are unlikely to be able to maintain their present levels of
productivity, much less of biodiversity, in the future," says Dr.

...[A]bout 20% of the arable land in 1950 has been lost subsequently,
to salinization [from salt left in the soil by irrigation],
desertification, urban sprawl, erosion, and other factors, so that we
are feeding 6.3 billion people today on about four-fifths of the land
on which we were feeding 2.5 billion people in 1950....

In sum, says Dr. Raven, "Over the past half century, we have lost
about a fifth of the world's topsoil, a fifth of its agricultural
land, and a third of its forests." By the middle of the present
century, 95% of tropical moist forests are expected to be lost.
Furthermore, "habitats throughout the world have [already] been
decimated, with populations of alien plants and animals exploding and
causing enormous damage throughout the world."

The Oceans

"About two-thirds of the world's fisheries are being harvested beyond
sustainability," says Dr. Raven. And, "Almost all major fisheries are
under severe pressure...."

The Atmosphere

"We have changed the composition of the atmosphere profoundly, first
by adding about one sixth to the carbon dioxide that is contributing
substantially to driving global temperatures upward and second, by
depleting the stratospheric ozone layer by about 8 per cent."

Fresh Water

...[W]e [humans] are consuming more than half of the total renewable
supplies of fresh water in the world, our use of water growing at
about twice the rate of our population growth. Our demands for water
are growing rapidly, while water tables across north China, India, and
other critical, densely populated regions are dropping rapidly.

Agriculture accounts for about 90% of the total water actually
consumed for human purposes, and it is not clear how we shall be able
to find water for a human population 50% larger than at present, one
with greatly increased demands for affluence. As it is, about half the
human population, some 3.5 billion people, will be living in regions
facing severe water shortages by 2025.


"The most troublesome environmental change of all, in that it is
irreversible, is the loss of biodiversity." Historically, extinction
has occurred naturally at the rate of about one species lost per
million species each year. "Historical records over the past few
centuries demonstrate that it has now risen by approximately three
orders of magnitude, to perhaps 1,000 species per million per year
(0.1 per cent of all species per year), and it continues to rise
sharply, with the accelerating destruction of habitats throughout the
world," Dr. Raven says.

"Species-area relationships, taken worldwide, lead to projections of
the loss of fully two-thirds of all species on Earth by the end of
this century.... And these projections do not include the inevitably
negative effects of climate change, widespread pollution, and the
destruction caused by alien species worldwide, among other factors."

[Did you get that? Two-thirds of all species on Earth may disappear
during this century -- and this projection does not take into
consideration the effects of climate change, widespread pollution, and
the destruction caused by alient species worldwide.]

"The significance of such a loss for global stability as well as human
progress is staggering," says Dr. Raven.

He goes on: "Striking is the fact that we are likely never to have
seen, or to be aware of, the existence of most of the species we are
driving to extinction. In tropical moist forest, we have catalogued so
far probably fewer than one in twenty of the species present -- which
is one reason that the losses are so tragic. The loss of so many
species clearly will have a negative impact on future human prospects.
We derive all of our food; most of our medicines; a major proportion
of our building materials, clothing, chemical feedstocks; and other
useful products from the living world."

In addition, the communities and ecosystems that it comprises protect
our watersheds, stabilize our soils, determine our climates and
provide the insects that pollinate our crops, among many other
ecosystem services.

And finally, says Dr. Raven, these organisms are simply beautiful,
enriching our lives in many ways and inspiring us every day. By any
moral or ethical standard, we simply do not have the right to destroy
them, and yet we are doing it savagely, relentlessly, and at a rapidly
increasing rate, every day. Many believe, and I agree with them, that
we simply do not have the right to destroy what is such a high
proportion of the species on Earth. They are, as far as we know, our
only living companions in the universe, Dr. Raven says.


"Summarizing, we can see that the world has been converted in an
instant of time from a wild, natural one to one in which human beings,
one of an estimated 10 million species of organisms (possibly many
more), are consuming, wasting, or diverting an estimated 45 percent of
the total net biological productivity on land and using more than half
of the renewable fresh water."

Dr. Raven says, "The scales and kinds of changes in the Earth's life
support systems are so different from what they have ever been before
that we cannot base our predictions of the future, much less chart our
future courses of action, on the basis of what has happened in the

[Continued next week.]