Applying Population Ecology: Human
Population and Urbanization
Chapter 7
Curitiba, Brazil
Fig. 7-1, p. 123
7-1 How Many People Can the Earth Support?
We do not know how long we can
continue increasing the earth’s
carrying capacity for humans without
seriously degrading the life-support
systems for us and many other
species.
Human Population Explosion

Exponential growth (J-curve) in past 200
years

Three major reasons
Ability to expand into diverse habitats
 Emergence of agriculture (Green Revolution)
 Sanitation systems and control of infectious
diseases

How Long Can the Human Population Grow

Rate slowing, but still exponential

Uneven global growth

No population can grow indefinitely

2050 global estimates: 7.2–10.6 billion people

97% growth in developing countries, least
likely to cope
Human Alteration of the Environment
Are There Too Many of Us?

Resources for growing population???

Positive viewpoint
 Technological
solutions
 Growing population a value resource

Negative viewpoint
 20%
currently lack necessities
 Declining conditions increase death rate
 Resource use already degrade environment

Optimum sustainable population


What is it???
Cultural carrying capacity = unknown
UN World Population Projections
Fig. 7-3, p. 126
What Factors Influence Population Size?

Concept 7-2A Population size increases
because of births and immigration and
decreases through deaths and emigration.

Concept 7-2B Total fertility rate is the key
factor that determines the population size.
Population Change
Population change =
(births + immigration) - (deaths + emigration)


Demographers look at birth rates and death
rates
Number of Children

Fertility rates affect population size and
growth rate

Replacement-level fertility rate (2.1)

Total fertility rate (TFR)
Most Populous Countries
Current and Projected Population Sizes by Region
Animations/size_region.html
U.S. Population

Quadrupled in 100 years, despite oscillations
in TFR

Baby boom: High TFR

Current births outnumbering deaths and legal
immigration

Growing faster than other developed
countries
Fertility Rate of the U.S. Population
Changes in the U.S. Population
Global Factors Affecting Birth Rates









(+) = increase rates
(-) = decrease rates
Children as part of labor force (+)
Cost of raising and educating children (-)
Availability of retirement systems (-)
Urbanization (-)
Educational and employment opportunities for women
(-)
Infant mortality rate (+)
Average marriage age (-)
Availability of legal abortion and reliable birth control
methods (-)
Religious beliefs, traditions, cultural norms (+)
Factors Affecting Death Rates

Average life expectancy increased


Population growth also response to decline in
crude death rate
Life expectancy and infant mortality rate
important indicators of overall health

Infant mortality – barometer of a society’s quality
of life
Migration

Migration driven by economic desires
(land of opportunity)

Other reasons
Religious persecution
 Political oppression
 Ethnic conflicts
 Wars
 Environmental degradation

The United States

Nation of immigrants

1820–1960: Most immigrants
European

Since 1960
Latin America – 53%
 Asia – 25%
 Europe – 14%

The United States

Opponents of immigration
Stabilize population sooner
 Reduce growing environmental impact
 60% of population favor reducing immigration


Proponents of immigration
Important historical role
 Do menial jobs and pay taxes
 Add cultural vitality
 Replace retiring baby boomers

Legal Immigration
7-3 How Does a Population’s Age Structure Affect Its
Growth or Decline?

Concept 7-3 The numbers of males
and females in young, middle, and
older age groups determine how fast
populations grow or decline.
Age Structure

Distribution of population
Prereproductive
 Reproductive
 Postreproductive

Country with many young people grows
rapidly
 Country with many older people will decline
 Developing countries >30% under 15 years
old

Population Age Structures
Male
Female
Expanding Rapidly
Guatemala
Nigeria
Saudi Arabia
Male
Female
Expanding Slowly
United States
Australia
China
Male
Female
Stable
Japan
Italy
Greece
Male
Female
Declining
Germany
Bulgaria
Russia
Fig. 7-8, p. 131
Examples of Age Structure
Animations/age_by_country.html
Global Connections
Fig. 7-9, p. 132
Age Structure Predicts the Future

50% of U.S. population baby
boomers

Graying of America

2043 – 25% of population over 65

Changes the economy
Tracking the Baby
Boomers
1955
1985
2015
2035
Stepped Art
Fig. 7-10, p. 132
Declines Occur in Aging Populations

“Baby bust” or “birth dearth” – TFR below 1.5
children per couple

Labor shortages

Strain on governments for public services

Fewer taxpayers
Rising Death Rate: The AIDS Tragedy

Disrupts social, economic structure

Removes productive young adults

Next 50 years, 278 million will die (mostly
African)

Eight African countries 16–39% infected
adults
7-4 How Can We Slow Population Growth?

Concept 7-4 Experience indicates
that the most effective ways to slow
population growth are to invest in
family planning, to reduce poverty,
and to elevate the status of women.
Stages of Demographic Transition

Preindustrial

Transitional – demographic trap

Industrial

Postindustrial
Stages of Demographic Transition
Stages of Demographic Transition
Stage 1
Preindustrial
Population
grows very
slowly
because of a
high birth
rate
(to compensate for
high infant
mortality) and
a high death
rate
Stage 2
Transitional
Population grows rapidly because birth
rates are high and death rates drop
because of improved food production
and health
Demographic Trap – resources
used up to support population
boom (exceeds carrying
capacity)
Stage 3
Industrial
Population
growth slows
as both birth
and death
rates drop
because of
improved
food
production,
health, and
education
Stage 4
Postindustrial
Population growth
levels off and then
declines as birth rates
equal and then fall
below death rates
Total population
Birth rate
Death rate
Fig. 7-12, p. 134
Demographic Transition Model
Animations/demo_transition.html
Family Planning can slow growth

Through birth spacing, birth control, health
care
Increase availability of contraception
 55% drop in TFR of developing countries


Developing countries
Almost half pregnancies unplanned
 Lack access to family planning


Replacement-level fertility achievable within
decades
By investing in family planning
 Reducing poverty

Results of Empowering Women

Educated women have fewer children
Illiterate women 64% of world’s population, 70%
of the poor
 When daughters considered less valuable, not
sent to school


Poor conditions for women leads to
environmental degradation
Slowing Population Growth in China

“One Child” - Halved birth rate and
drastically reduced TFR
Strict family planning
 Sons still preferred – gender imbalance
 Population rapidly aging


Rapidly growing economy - seen improved
quality of life
Larger middle class increases resource
consumption and waste
 Sustainable economic plan needed to avoid
environmental degradation

Slowing Population Growth in India

Tried to slow population growth for five
decades

Most populous country in 2015

Problems increase with growing population
Poverty
 Malnutrition
 Environmental degradation
 Growing middle class – resource consumption

7-5 What Are the Major Population and
Environmental Problems of Urban Areas?

Concept 7-5 Cities can improve
individual lives, but most cities are
unsustainable because of high levels
of resource use, waste, pollution,
and poverty.
Urban Living

Half the world lives in urban areas

80% of Americans in cities

Urban areas continue to grow
Natural increase
 Immigration

Major Global Trends in Urban Growth

Proportion of urban global population growing

Number and sizes of urban areas mushrooming

Rapid increase in urban populations in developing
countries

Urban growth slower in developed nations

Poverty increasing
Urban Areas and Megacities
Urbanization in the U.S.

1800–2007, increased population 5–80% in
urban areas

Migration patterns

Better working and housing conditions
compared to the past

Problems in urban areas (go over later)
Major Urban Centers in
the United States
SF Bay Region Growth
Animations/sf_sprawl.html
Advantages of Urbanization

Economic development

Innovation

Education and jobs

Technological advances

Recycling more economically feasible

Longer life spans
Disadvantages of Urbanization

Unsustainable systems

Occupies 2%, consumes 75%
Lack of vegetation (contributes to air
pollution)
 Water problems
 Pollution and health problems
 Noise pollution
 Climate and artificial light
 Urban heat islands
 Light pollution

Urban Areas Are Rarely Sustainable
Noise Levels
Urban Sprawl

Gobbling up countryside

Causes
Prosperity
 Ample and affordable land
 Automobiles
 Cheap gasoline
 Poor urban planning

Urban Sprawl Around Las Vegas
Stepped Art
Fig. 7-15, p. 139
Consequences of Urban Sprawl

Inadequate mass transportation

Need to drive everywhere

Decreased energy efficiency

Traffic congestion

Destruction of prime cropland, forests, wetlands
U.S. Megalopolis: Bowash
Fig. 7-17, p. 140
Urban Poor in Developing Countries

Slums

Shantytowns and squatter
settlements

Lack of basic services
Living in a Shantytown
Fig. 7-20, p. 143
Case Study: Mexico City








Large population
Severe noise, water, and air pollution
50% unemployment
>33% live in barrios
100,000 premature deaths per year
3 million without sewer
 Fecal snow
Progress – tree planting and lower air pollution
Geography contributes to air pollution
Thermal Inversion and Smog
Animations/thermal_inversion.html
7-6 How Does Transportation Affect Urban
Development?

Concept 7-6 A combination of plentiful
land, inexpensive fuel, and an expanding
network of highways results in dispersed
cities that depend on motor vehicles for
most transportation.
Cities Can Grow Outward or Upward

Compact cities
Transportation by walking, biking, or
mass transit
 Hong Kong, Tokyo


Dispersed cities
Transportation by automobile
 Most American cities

Formation of Photochemical Smog
Animations/photochemical_anim.html
Automobiles in the United States

<10% of world’s population own 1/3 of cars
Gas guzzlers
 40,000 people per year die from auto accidents
 Largest source of air pollution
 Lead to urban sprawl and congestion

Reduce Automobile Use

HOW
User-pays system
 Full-cost pricing
 Tax revenues to finance mass transit, bike
paths, sidewalks


High gasoline tax unlikely

Need to discourage automobile use
Alternatives to Cars

Bicycles

Mass transit systems in urban areas

Bus systems

Rapid rail
Trade-offs: Bicycles
Fig. 7-21, p. 145
Trade-offs: Mass Transit Rail
Fig. 7-22, p. 145
Trade-offs: Buses
Fig. 7-23, p. 146
Trade-offs: Rapid Rail
Fig. 7-24, p. 146
7-7 How Can Cities Become More Sustainable
and Livable?

Concept 7-7 An ecocity allows
people to: choose walking, biking, or
mass transit for most transportation
needs; recycle or reuse most of their
waste; grow much of their food; and
protect biodiversity by preserving
surrounding land.
Environmentally Sustainable Cities

Smart growth

Ecocities
Build and design people-oriented cities
 Use energy and matter efficiently
 Prevent pollution and reduce waste
 Recycle, reuse, and compost
 Protect and encourage biodiversity

Smart Growth and New
Urbanism