Page 23 - Environment: The Science Behind the Stories

Renewable natural Nonrenewable natural
resources resources
• Sunlight • Fresh water • Crude oil
• Wind energy • Forest products • Natural gas
• Wave energy • Agricultural crops • Coal
• Geothermal energy • Soils • Copper, aluminum, and
other metals
FIGURE 1.1 Natural resources lie along a continuum from perpetually renewable to nonrenewable.
Perpetually renewable, or inexhaustible, resources such as sunlight and wind energy (left), will always be there
for us. Renewable resources such as timber, soils, and fresh water (center) may be replenished on intermediate
time scales, if we are careful not to deplete them. Nonrenewable resources such as oil and coal (right) exist in
limited amounts that could one day be gone.

Population growth amplifies our impact produced more food to meet their nutritional needs and began
having more children.
For nearly all of human history, fewer than a million people The second notable phenomenon, known as the industrial
populated Earth at any one time. Today our population has revolution, began in the mid-1700s. It entailed a shift from rural
grown beyond 7 billion people. This means that for every one life, animal-powered agriculture, and handcrafted goods toward
person who used to exist, several thousand people exist today! an urban society provisioned by the mass production of factory-
FIGURE 1.2 shows just how recently and suddenly this dramatic made goods and powered by fossil fuels (nonrenewable energy
change has come about. sources including oil, coal, and natural gas; pp. 542–544).
Two phenomena triggered our remarkable increase in Industrialization brought technological advances and improve-
population size. The first was our transition from a hunter- ments in sanitation and medicine, and it enhanced agricultural
gatherer lifestyle to an agricultural way of life. This change production through the use of fossil-fuel-powered equipment
began around 10,000 years ago and is known as the agricultural and synthetic pesticides and fertilizers (pp. 236, 265).
revolution. As people began to grow crops, domesticate ani- The factors driving population growth have brought us
mals, and live sedentary lives on farms and in villages, they better lives in many ways. Yet as our world fills up with peo-
ple, population growth has begun to threaten our well-being.
We must ask how well the planet can accommodate 7 billion
7 of us—or the 9 billion forecast by 2050. Already our sheer
6 numbers, unparalleled in history, are putting unprecedented
5 stress on natural systems and the availability of resources.
4 Resource consumption exerts social

Agricultural 3 Human population (billions) and environmental pressures
revolution
Industrial 2 Besides stimulating population growth, industrialization
revolution 1 increased the amount of resources each one of us consumes. As

0 we mined energy sources and manufactured ever-greater num-
10,000 yr 0 500 1000 1500 2000 bers of goods, we enhanced the material affluence of many of
before present the world’s people. In the process, however, human society has
Year consumed more and more of the planet’s limited resources.
FIGURE 1.2 The global human population increased after the One way to quantify resource consumption is to use the
agricultural revolution and then skyrocketed as a result of concept of the “ecological footprint,” developed in the 1990s by
the industrial revolution. Data compiled from U.S. Census Bureau, U.N. environmental scientists Mathis Wackernagel and William Rees.
22 Population Division, and other sources. An ecological footprint expresses environmental impact in terms

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