Chapter 7
The Human Population
World Population
Fig. 1-1 p. 2
11/13/2014
2
World Population Growth, in Billions
Number of years to add each billion (year)
All of Human History
(1800)
130 (1930)
30 (1960)
15 (1975)
12 (1987)
12 (1999)
14 (2013)
14 (2027)
Over the last 150
years, fossil fuel
use has allowed
the human
population to
soar
21 (2048)
Sources: First and second billion: Population Reference Bureau. Third through ninth billion: United Nations, World
Population Prospects: The 2004 Revision (medium scenario), 2005.
Population Density
Population density = # of individuals
unit area.
Figure
7.1
Projecting Future Population Numbers
Malthus predicted that
human growth rate would
exceed carrying capacity
Disease, war, famine
would result
Prediction: by the end of the 21st
century, 11-12 billion people
Figure
7.1
Scientists Disagree on
Earth’s Carrying Capacity
• The following graphs
show theoretical
models of food
supply and
population size.
• Notice the part that
innovation plays
• But how did we get
to 7 billion people?
5 Factors that Drive
Human Population Growth
•
Demography- the study of human
populations and population trends.
1. Changes in Population Size
2. Fertility
3. Life Expectancy
4. Age Structure
5. Migration
#1. Changes in Population Size
•
•
•
Immigration- the movement of people into a country
Emigration- the movement of people out of a country.
Net migration rate- the difference between
immigration and emigration in a give year per 1,000
people in the country.
#1. Changes in Population Size – the Math
•
•
Crude birth rate (CBR)= the number of births per
1,000 individuals per year.
Crude death rate (CDR)= the number of deaths per
1,000 individuals per year.
*Global population growth rate = (CBR- CDR)/ 10
*National population growth rate =
[(CBR+ immigration) - (CDR + emigration)] ÷ 10
*Doubling time (in years) =
70/growth rate
#1. Changes in Population Size
Growth Rates
Growth Rate Numbers
•Negative = < 0%
•Slow = 0 to 1%
(USA)
•Moderate = 1 to 2%
(South America)
•High = 2 to 3%
(Central America)
•Extreme = > 3%
(Africa)
#1. Changes in Population Size
Why the increase ?
Death rate have come down!
•
•
•
•
•
Better medicine
Reliable food
Good nutrition
Better sanitation
Safer water
#2. Fertility
•
•
Total fertility rate (TFR)the average number of children
that each woman in a
population will bear in her
reproductive years. (0 - 5+)
In 2013, TFR = 2.5
(Greater than 2.1 which represents no
population growth)
•
•
1.5 in developed countries
3.3 in developing countries
#2. Fertility – Why the difference?
ECONOMICS
•
•
Developed countriescountries with
relatively high levels of
industrialization and
income.
Developing countriescountries with
relatively low levels of
industrialization and
income of less that $3
per person per day.
#3. Life Expectancy
•
Life expectancy- the average number of years that
an infant born in a particular year in a particular
country can be expected to live, given the current
average life span and death rate of that country.
#3. Life Expectancy
•
•
Infant mortality rate- the number of deaths of
children under 1 year of age per 1,000 live births.
Child mortality rate- the number of deaths of
children under age 5 per 1,000 live births.
Developed Countries –
Low mortality rate
(good health care)
Developing Countries –
High morality rate (poor
health care)
#4. Age Structure
• Age structure
diagrams
(population
pyramids)- visual
representations of
age structure
within a country
for males and
females.
#4. Pyramid Age Structure
A lot of people at or near child bearing years
#4. Rectangle Age Structure
Just enough infants to replace older people
#4. Inverted Age Structure
Not enough reproductive women
#4. Age Structure Diagrams
#4. Age Structure Diagrams
Developed Country
vs
Developing Country
It is estimated by 2020, 85% of the world’s population
will live in developing countries
#5. Migration
Migration of people, into
and out of a cities and
countries, can be a major
issue.
•
•
•
Immigration – people
coming in
Emigration – people
going out
Net Migration Rate =
immigration - emigration
Chapter 7
Many Nation go through Demographic Transition
The Demographic Transition
•
The theory of the demographic transition is the theory
that as a country moves from a subsistence economy to
industrialization and increased affluence, it undergoes a
predictable shift in population growth.
The Stages of the Demographic Transition
Phase 1
Slow
population
growth
because
there are
high birth
rates and
high death
rates which
offset each
other.
The Stages of the Demographic Transition
Phase 2
Rapid population
growth because
birth rates remain
high but death
rates decline due
to better
sanitation, clean
drinking water,
increased access to
food and goods,
and access to
health care.
The Stages of the Demographic Transition
Phase 3
Stable
population
growth as the
economy and
educational
system
improves and
people have
fewer children.
The Stages of the Demographic Transition
Phase 4
Declining
population
growth because
the relatively high
level of affluence
and economic
develop
encourage
women to delay
having children.
Family Planning
•
Family planning- the regulation of the number or
spacing of offspring through the use of birth
control.
The 12 Most Populous Countries in the World
Notice:
*Developed vs
Undeveloped
*China, India &
United States
Ecological Footprints
•
Affluence - having a lot of wealth such as
money, goods, or property uses a lot of
resources and creates a larger ecological
footprint
The IPAT Equation
• To estimate the impact of human lifestyles on
Earth we can use the IPAT equation:
• Impact= Population X Affluence X Technology
Urban Areas greatly affects IPAT
More than ½ of the world’s population
lives in urban areas. The more affluent
the urban area… the more pollution…
the more environmental impact.