Page 24 - Environment: The Science Behind the Stories

1.6 Biocapacity
Global footprint (number of planets) 1.0 Ecological footprint Overshoot
1.4
1.2

0.8

0.6
0.4

0.2
0
1960 1970 1980 1990 2000
Year

FIGURE 1.4 Data indicate that we have overshot Earth’s
biocapacity—its capacity to support us—by 50%. We are
using renewable natural resources 50% faster than they are being
replenished. Data from WWF, 2012. Living planet report 2012. WWF Interna-
tional, Gland, Switzerland.
How much larger is the global ecological footprint today
than it was half a century ago?

society, but historical evidence shows that civilizations can
crumble when pressures from population and consumption
FIGURE 1.3 An “ecological footprint” represents the total overwhelm resource availability. Historians have inferred that
area of biologically productive land and water needed to environmental degradation contributed to the fall of the Greek
produce the resources and dispose of the waste for a given and Roman empires; the Angkor civilization of Southeast
person or population. Adapted from an illustration by Philip Testemale in Asia; and the Maya, Anasazi, and other civilizations of the
Wackernagel, M., and W. Rees, 1996. Our ecological footprint: Reducing human New World. In Iraq and other regions of the Middle East,
impact on the Earth. Gabriola Island, British Columbia: New Society Publishers.
areas that are barren desert today were lush enough to sup-
port the origin of agriculture when great ancient societies
of the cumulative area of biologically productive land and water thrived there. Easter Island has long been held up as the most
required to provide the resources a person or population con- striking case of a society’s self-destruction after depleting its
sumes and to dispose of or recycle the waste the person or popu- resources, although new research disputes this interpretation
lation produces (FIGURE 1.3). It measures the total area of Earth’s (see THE SCIENCE BEHIND THE STORY, pp. 24–25).
biologically productive surface that a given person or population In his 2005 book Collapse, scientist and author Jared
“uses” once all direct and indirect impacts are totaled up. Diamond synthesized existing research and formulated gen- CHAPTER 1 • SCIENCE AND SUSTAIN ABILITY : AN INTR ODUCTI ON T O ENVIR ONMENTAL SCIENCE
For humanity as a whole, Wackernagel and his colleagues eral reasons why civilizations succeed and persist, or fail and
calculate that our species is now using 50% more of the plan- collapse. Success and persistence, he argued, depend largely
et’s resources than are available on a sustainable basis. That on how societies interact with their environments and on how
is, we are depleting renewable resources by using them 50% they respond to problems.
faster than they are being replenished. This is essentially like In today’s globalized society, the stakes are higher than
drawing the money out of a bank account rather than living off ever because our environmental impacts are global. If we
the interest the money makes. This excess use has been termed cannot forge sustainable solutions to our problems, then the
overshoot because we are overshooting, or surpassing, Earth’s resulting societal collapse will be global. Fortunately, envi-
capacity to sustainably support us (FIGURE 1.4). ronmental science holds keys to building a better world. By
Moreover, people from wealthy nations such as the studying environmental science, you will learn to evaluate the
United States have much larger ecological footprints than many changes happening around us and to think critically and
do people from poorer nations. If all the world’s people con- creatively about ways to respond.
sumed resources at the rate of U.S. citizens, we would need
the equivalent of four planet Earths.
The Nature of

Environmental science can help Environmental Science
us avoid past mistakes
Environmental scientists aim to comprehend how Earth’s nat-
It remains to be seen what consequences resource consump- ural systems function, how these systems affect people, and
tion and population growth will have for today’s global how we are influencing those systems. Many environmental 23

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