Transcript Document
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