Page 34 - Environment: The Science Behind the Stories

Human Influence Index

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FIGURE 1.13 Human settlement, roads and transportation networks, nighttime light pollution, and
agriculture and other land uses all influence terrestrial ecosystems. A U.S. map summarizing these influ-
ences shows that we live in a highly modified environment and suggests we would be wise to carefully nurture
natural systems and manage remaining resources. Used by permission of the Center for International Earth Science Informa-
tion Network (CIESIN), The Earth Institute, Columbia University. © 2012.
Can you find where you live on the map? Do the ecosystems in your area experience a more-than-
average, less-than-average, or average amount of human influence? What human impacts do you
think most affect natural systems in your region?

landscapes in which we live (FIGURE 1.13). They are also driv- However, in extracting coal, oil, and natural gas, we are
ing the loss of Earth’s biodiversity (Chapter 11)—perhaps our splurging on a one-time bonanza, for these fuels are nonre-
greatest problem, because extinction is irreversible. Once a newable and in finite supply. Scientists calculate that we have
species becomes extinct, it is lost forever. depleted roughly half the world’s conventional oil supplies
The most comprehensive scientific assessment of the con- and that a crisis could hit once supply begins to decline while
dition of the world’s ecological systems and their capacity to demand continues to rise (pp. 550–551). How we handle
continue supporting our civilization was completed in 2005, future fossil fuel shortages will greatly influence the nature of
when over 2000 leading environmental scientists from nearly our lives in the 21st century.
100 nations completed the Millennium Ecosystem Assessment CHAPTER 1 • SCIENCE AND SUSTAIN ABILITY : AN INTR ODUCTI ON T O ENVIR ONMENTAL SCIENCE
(TABLE 1.1). The Millennium Ecosystem Assessment makes TABLE 1.1 Main Findings of the Millennium Ecosystem
clear that our degradation of environmental systems is having Assessment
negative impacts on all of us, but that with care and diligence
we can still turn many of these trends around. • Over the past 50 years, people have altered ecosystems
more rapidly and extensively than ever, largely to meet grow-
ing demands for food, fresh water, timber, fiber, and fuel.
This has caused a substantial and largely irreversible loss in
Our energy choices will influence the diversity of life on Earth.
our future enormously • Changes to ecosystems have contributed to substantial
net gains in human well-being and economic development.
Our reliance on fossil fuels to power our civilization has inten- However, these gains have been achieved at growing costs,
sified virtually every impact we exert on our environment, including the degradation of ecosystems and the services
from habitat alteration to air pollution to climate change. they provide and, for some people, the worsening of poverty.
Fossil fuels have also helped to bring us the material afflu- • This degradation could grow significantly worse during the
ence we enjoy. By exploiting the richly concentrated energy first half of this century.
in coal, oil, and natural gas, we have been able to power the • We can reverse the degradation of ecosystems while meet-
machinery of the industrial revolution, produce the chemicals ing increasing demands for their services, but doing so will
that boost agricultural yields, run the vehicles and transpor- require that we significantly modify many policies, institu-
tation networks of our mobile society, and manufacture and tions, and practices.
distribute our countless consumer products. The lifestyles we Adapted from Millennium Ecosystem Assessment, 2005.
lead today are a direct result of the availability of fossil fuels Ecosystems and human well-being: biodiversity synthesis. World
(Chapter 19). Resources Institute, Washington, DC. 33

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