Lesson 36: Projecting Future Populations
In this lesson,
we will look at how population is changing all over the world and the factors
involved in those changes. We will also look at birth and death rates and how
they are used to calculate change in population.
Despite declining total fertility rates (TFR) in developed countries -- down
from 5.0 in the 1960s to 2.0 in the 21st century -- populations continue to
grow worldwide at the rate of 78 million per year (2010 data).
In addition to
the fertility rate, the rate of population growth varies depending upon the age
at which women start giving birth. A population where the women have children
at a younger age will grow faster than other populations where women give birth
later in life. Longevity is the life span of an individual, which has increased
worldwide as well.
A population profile is a bar graph showing the number of people at each age
for a given population. Population profiles are frequently used to analyze
changes in populations over a specified period of time. A population profile
also basically represents the age structure of a population. For example, the
United States has a mixture of both young and old populations. Many third-world
countries lean heavily towards younger populations, resulting in explosive
population growth while several wealthier nations have older or graying
populations.
In Italy and Japan, populations will be graying as the number of elderly people
increases. Europe is also in the midst of an immigration wave, responding to
international crises. Immigration does provide new workers and youth but also
challenges existing culture, art and religion.
The United States has a fertility rate of 2.1 and
has accepted immigrants every year. Expected population is 439 million by 2050.
In developing countries, the fertility rate is 3.2, similar to the United
States at the peak of the baby boom period.
Population momentum is the effect of current age structures on future
populations.
CBR or crude birth rate is the number of births per 1,000 per year. CDR or
crude death rate is the number of deaths per 1,000 per year. The term ‘crude'
is used because there is no consideration of whether the individual is old or
young, male or female.
You can determine the change in population using this formula:
% increase or decrease in population: (CBR - CDR) ÷ 10