Geography Reference
In-Depth Information
Globally, about 46 percent of the human race is categorized as urban, but the figures vary sharply
from one continent to the next. The populations of North America, South America, and Europe are
each at least 70 percent urbanized. In contrast, the urban population percentages of Asia and Africa
are 47 percent and 33 percent respectively, which largely reflect continued heavy reliance on manual
labor in the agricultural sector of countries' economies, plus relative lack of employment opportunit-
ies in the service and manufacturing sectors, which globally tend to be more urban-based.
Going Ballistic: Population Growth
For the vast majority of human history, total population was much, much lower than it is
today. The United Nations estimates that it was only about the year 1650 that, for the first
time, as many as 500 million people were alive at any one time (as illustrated by Figure 11-3).
Until then, population growth could be fairly characterized as a gently rising straight line. But
around 1650 something began to happen. The line started to curve upward — gently at first,
but then ballistically.
Total population passed 1 billion around 1800. Thus, while it took untold eons for human numbers to
reach 500 million, a mere 150 years were required to double that number. By about 1925, the figure
had doubled again to about 2 billion. In the next fifty years, it doubled again, reaching 4 billion some-
time around 1975. And here we are today at slightly more than 6.1 billion.
Figure 11-3:
Global popula-
tion growth.
Globalpopulationgrowthhasnotstopped.Insteaditwillcontinuetoriseinthepresentcenturybefore
leveling off at about 10 billion in the year 2100. Naturally, that may cause you to ask, “How can
demographers be so certain about the future course of the world's population?” In fact, the experts
