World Population
The World at 7 Billion
Quick Write
• What factors may cause us to see an
increase or decrease in world population?
• What possible effects does an increase in
world population have on society?
Demographic Transition
• Dramatic changes followed first the Agricultural
Revolution some 8,000 years ago
• Also occurred following the Industrial Revolution 250
years ago
o
Improvements in food supply and changes in health and
hygiene triggered unprecedented population growth
Demographic Transition
• Throughout much of history human
populations have been characterized by
relative stability
• High birth rates and high death rates fluctuating
around a low growth equilibrium.
The Classic Stages of Demographic
Transition
Phase 1
Phase 2
Phase 3
High Birth Rate,
Declining Birth Birth Rate
Fluctuating Death and Death Rates Approaching
Rate
Replacement
Phase 4
Low to Very Low
Birth Rate,
Very Low Death Rate
Birth rate
Natural
increase
Death rate
Time
Note: Natural increase or decrease is the difference between the number of births and deaths. The birth
rate is the number of live births per 1,000 population in a given year. The death rate is the number of
deaths per 1,000 population in a given year.
The Four Phases of Demographic
Transition
• In Phase 1 there is a fluctuating death rate
o In the parish of Mouy, France there were 47 burials recorded in 1693 and
in 262 in 1694
o A rise in the price of grains meant more people could not afford food
• In Phase 2 death and birth rates begin to fall more regularly
o Roughly the beginning of the Industrial Revolution
• Increasing urbanization lessened the need for children
• Public health measures improved life spans.
• In Phase 3 Birth rates increased
o In the aftermath of World War II the benefits of public health and modern
medicine became available
o Mortality fell rapidly but the desire for large families existed
• In Phase 4 low death rates combined with low birth rates
o There was mounting concern over record rates of population growth so
birth rates began to fall in many countries
Demographic Transition
This classic model is based on the experience
of Western Europe, in particular England and
Wales.
Year
Crude
Birth Rate
Crude Death
Rate
Population
(millions)
1750
40
40
6
1800
34
20
9
1850
34
22
18
1900
28
16
32
1950
16
12
44
2000
11
10
60
The Four Phases of Demographic
Transition: Evident Today Around the
World
PHASE 1
Afghanistan
Uganda
Zambia
PHASE 2
Ghana
Guatemala
Iraq
PHASE 3
India
Gabon
Malaysia
PHASE 4
Brazil
Germany
Japan
Birth Rate
44
46
46
Death Rate
16
12
15
31
30
35
8
6
6
23
27
21
7
9
5
15
8
8
6
10
9
7 Billion People
• The Population is now estimated at over 7
billion.
o This doubled the population of 1965.
o The recent growth in the size of World Population is more rapid
that ever before.
o Birth and death rates are affected by many events
throughout world history
• Technological and social factors
influence where, when, and why
population size changes
Rapid Population Growth
• The World is in the midst of its most rapid population
growth in history
o Annual population growth rate has declined to 1.2 percent per year but
world population grows by about 83 million annually.
• While declines in birth rates have been virtually
universal across countries, the pattern of decline
has been very variable.
o In some countries, birth rates have fallen below two children
o Birth rates in other countries have decreased to medium levels or have
barely begun to decrease.
o Population projections assume that birth rates in developing countries will
decline to two children or fewer
• Both the sixth billion and seventh billion were
reached in the same number of years: a record 12.
o
The eighth billion may also take 12 years but only if birth rates decline
according to projections.
Predictions
• The UN estimates that world population will be
over 10 billion by 2100.
o How might your life or your children’s lives
be different if this is true?
o What advancements do you think would
have to be made in education, medicine,
environmental issues, and food and water
supply in order to support a global
community of 10 billion people?