November/December
2000
Rainforests
and Mass Extinction
By Tim Keating
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When I was in grade school,
it was thought that Earth supported about a million species of
unique
life forms. Recently, however, I attended a conference on Biodiversity
at the American Museum of Natural History that was the kickoff
to the
opening of their Biodiversity exhibit. There, I learned that it is
now currently accepted that Earth supports at least 13 to 15 million
species
of life. This is the figure that was put forth at the conference by
some of the world’s leading natural scientists. But recent
studies show that even this figure is extremely conservative.
For example, one scientist, Terry Erwin, has conducted research
on beetles in the rainforests of Peru. Dr. Erwin’s research points to a level
of diversity of beetles in the world’s rainforests that surpasses
the above figure for all species by a factor of two. Erwin found over
a thousand species of beetles on a single rainforest tree, the vast
majority of which had never before been catalogued by scientists. Moreover,
Dr. Erwin found that the commonalty of beetle species on the trees
dropped
to as low as 20 percent among trees that were relatively near one another.
In other words, on another tree just 50 meters away, over a thousand
species were found, but about 80 percent of them were not the same
as
those on the first tree. Erwin repeated the method on a third tree
and found the same results. This has led him to estimate that Earth
supports
30 or even 100 million species of beetles alone!
Another speaker at the conference gave some early results of DNA testing
of soil microbes from around the world. It used to be thought that
soil
organisms were similar worldwide since microbes can easily move from
one location to another in water and even in water vapor, such as clouds.
But preliminary studies are evaporating these old assumptions. In fact,
it seems that the microbes account for the vast majority of Earth’s
biodiversity, and that the medium and large flora and fauna actually
comprise just a small percentage of Earth’s total species diversity.
In fact, the total number of species on Earth could be much higher
than 100 million. We just don’t know. It could be 15 million or
150 million. It could be even higher than that.
A Tale of Numbers
For the sake of argument, let’s use the figure that is currently
the best guess of a number of leading scientists—14 million species.
At the Biodiversity conference, Nigel Sizer, a biologist at the Missouri
Botanical Gardens, gave this estimate: “At least half of Earth’s
unique species of plants, animals and in-between are found in tropical
rainforests.” This figure, too, is probably conservative, as current
research (like that on microbes and beetles) points to a number that
may be as high as 90 percent. But for now, let’s stick with Sizer’s
estimate of 50 percent.
Government estimates put the rate of loss of tropical forests globally
at 15 million hectares a year (a hectare is 2.47 acres—about the
size of two and a half football fields), which is roughly two times
the size of New York state. Figures for deforestation are notoriously
underestimated. Governments are reluctant to present figures as they
really are, because reports of the alarmingly rapid rate of deforestation
can have negative repercussions—true reports of logging and deforestation
can even affect multilateral loans, as recently happened in Indonesia.
The United Nations Food and Agriculture Organization and the International
Timber Trade Organization are two groups that maintain and assess figures
for deforestation. Both groups consider deforestation to be the total
loss of tree cover. But numbers can be misleading. Tropical forest
loss
is actually much greater since heavy degradation can occur while some
tree cover still remains. Such degradation is hard to observe in satellite
images and is therefore mostly overlooked. Recent research that “ground-truthed” (that
is, compared satellite images and estimates with on-the-ground observations)
showed that estimates of rainforest loss should be at
least doubled in areas where logging is occurring.
So, the real numbers are more like 20 to 25 million hectares a year:
that’s one and a half to two acres of tropical forests disappearing
every second of every minute of every day of the year.
Going, going...Gone?
Before the Spanish conquest of the Americas, rainforests once covered
15 percent of Earth’s entire land area. That area has been reduced
to between six and seven percent due to the clearing and burning associated
with the growth of civilization.
Nigel Sizer put it this way: “At the current rate of loss, Earth’s
rainforests will have been totally wiped out (except for less accessible
remnants and a few parks) within 50 years.” Some estimates forecast
that the complete loss of rainforests will occur sooner than that—in
as little as 35 years.
But let’s say that Earth’s rainforests will be gone in 50
years; and that there are 14 million species on Earth; and that half
of all species are found in tropical rainforests. If we do the math,
that means that seven million species may be extinct in 50 years. That’s
140,000 species becoming extinct every year; 383 species a day; 16 species
an hour and a species going extinct every 3.75 seconds. And that’s
just a conservative estimate.
The Time is...Now
We are right now in the midst of the greatest mass extinction of
species the Earth has known in the last 65 million years—and perhaps
the greatest mass extinction Earth has ever known.
A recent study has shown that mass extinction will last far into the
future, and that it could take as long as 10 million years for even
a semblance of diversity to recover. It is now widely accepted that
roughly 65 million years ago, an asteroid collided with Earth, creating
an upheaval that eventually led to the extinction of as much as 95
percent
of all species on Earth. This catastrophe is said to have wiped out
the dinosaurs and millions of other life forms. The fossil record also
reveals four other mass extinctions in the history of life on Earth.
But recent research has shown that the current mass extinction—this
one perpetrated by humans we call ‘civilized’—may be
happening at a faster rate than ever before.
Much of the destruction of rainforests—and thus the current rate
of mass extinction—is the result of overconsumption of wood, paper,
gold, aluminum, coffee, bananas, chocolate and other products. We all
must reduce the demand for rainforest-destructive products. In part
two of this article in next month’s Satya find out how we can
end the demand for tropical woods in the U.S., slow the logging of
tropical
forests and thus slow the mass extinction of the species of the Earth.
Tim Keating is co-founder and Executive Director of Rainforest
Relief, a New York-based organization that works through education and
direct-action campaigns to reduce the demand for wood products and materials,
which is driving the destruction of rainforests worldwide. For more
information or to volunteer, contact: (718) 398-3760 or relief@igc.org.
