ENVIRONMENTAL SCIENCE
CHAPTER 6:
The Human Population
and Urbanization
Core Case Study: Are There
Too Many of Us?
• 6.8 billion people
• 82 million more each year
• 2050: 9.5 billion people at current growth
rates
• Most growth in low-income and middleincome countries
• Are there enough resources for this
growing population?
Core Case Study: Are There
Too Many of Us?
• Negative viewpoint
– At present, 20% currently lack basic necessities
– Declining conditions have increase death rate
– There is an increased in our resource use
– Increased environmental degradation
• Positive viewpoint
– Technological solutions will allow us to increase our
carrying capacity
– Growing population in of itself is a valuable
resource
Sect. 6-1: How Many People
Can the Earth Support?
• Concept To Learn in Sect. 6-1:
We do not know how long we can
continue increasing the earth’s
carrying capacity for humans without
seriously degrading the life-support
system that keeps us and many other
species alive.
How Many People Can the
Earth Support?
• Read “Human population growth
continues but it is unevenly
distributed”, pages 95-96.
Human Population Explosion
• Exponential growth (J-curve) in past 200
years
• Three major reasons
– Humans have ability to expand into diverse
habitats
– Development of modern agriculture, which
has created more available food
– Sanitation systems and control of
infectious diseases has decreased death
rates
How Long Can the Human
Population Grow
• Rate slowing, but its still exponential at 1.22%
per year
• Uneven global growth (more in low
income/developing countries)
• Can we grow indefinitely?
• Science: No population can grow indefinitely!
• 2050: 9.5 billion people at current growth rates
• Most of growth in developing countries, least
likely to cope (What is different there
compared to developed countries?)
Cultural Carrying Capacity
• Read:“CULTURAL CARRYING CAPACITY:
A biological approach to human problems”
by Garrett Hardin (URL on my web page)
Assignment:
1. What inferences about carrying capacity can be made
by studying carrying capacity in a non-human setting?
2. How does carrying capacity relate to quality of life?
3. What is the conflict that exists between economists &
ecologists?
4. How does Hardin suggest that we make corrections to
overpopulation?
Sect. 6-2: What Factors Influence
the Size of the Human Population?
• Concepts to learn in Sect. 6-2A:
Population size increases through births
and immigration and decreases through
deaths and emigration.
• Concept to learn in Sect. 6-2B: The
average number of children born to
women in a population (total fertility
rate) is the key factor that determines
the population size.
Population Change: Growth,
Decline, or Stability
• Population change =
(births + immigration) - (deaths + emigration)
1. within a specific area, during 1 year
2. which ever category is greater will dictate an
increase or decrease in population
• Demographers look at birth rates and death rates
(the rate of births or deaths per 1000 people)
• In 2009:
– China: 1.3 billion people
– India: 1.1 billion people
– USA: 306 million people (we’re third!)
Number of Children born
• Fertility rates: The key factor in
determining population size.
1. Affects population size and growth rate
• Total fertility rate (TFR): the average # of
children born to women in a population
during their reproductive years
• From1950 to 2009: Global TFR fell to:
– 1.6 from 2.5 in developed countries
– 2.8 from 6.5 in developing countries
Case Study: The U.S.
Population Is Growing Rapidly
• Quadrupled in 100 years, despite
oscillations in TFR
• Baby boom: had a high TFR
• Current births are still outnumbering
deaths and immigration out of the US
• Our growth is faster than other
developed countries
• 2050 estimate: 439 million in the US
alone
Baby Boomers: In-class
assignment
Answer the following:
1.What was the total population change that
took place during the baby-boomer era?
2.What % of the current population do the
baby-boomers represent?
3.What was the peak year & what was the
total increase?
4.Have there been any other similar spikes
in population? What year?
Case Study: The U.S.
Population Is Growing Rapidly
• Why is the US growth rate faster/greater
than any other developed country?
1. Birth rate vs. death rate
2. Immigration vs. emmigration
• How has the US ecological footprint
changed since the early 1900’s?
1. Disease?
2. Resource use?
3. Environmental impact per person?
Factors Affecting Birth & Fertility
Rates
• Importance of children as part of labor force
1. Have children, for the purpose of working and
contributing their income to the family budget.
• Cost of raising and educating children
1. Very high in developed countries
a. Approx. $300,000 till age 18 (middle class)
2. Lower in developing countries
a. Need their children to go to work to survive.
Factors Affecting Birth & Fertility
Rates
• Availability of retirement systems (pensions)
1. reduce the need to have children
• Urbanization
1. Better access to family planning.
• Educational and employment opportunities
for women
1. the greater the opportunities, the lower
will be the birth rates & TFR
Factors Affecting Birth & Fertility
Rates
• Average marriage age
1. Rates are lower if average age is 25+
• Availability of legal abortion and reliable birth
control methods
• Religious beliefs, traditions, cultural norms
1. Will favor large families
2. Strongly oppose abortion laws.
Factors Affecting Death Rates
• Population growth is also response to decline
in crude death rate
• What factors have lowered death rates?
• Both Life expectancy and infant mortality
rate important indicators of overall health
• Average life expectancy increased (77 years)
• Infant mortality – barometer of a society’s
quality of life
1. # of babies/1000 that die before their 1st birthday
Infant Mortality Rates: an
indicator of overall health
• Which country in the world has the
lowest Infant Mortality Rate?
• What is the rate for the US?
• Where do we rank in the world for
Infant Mortality Rate?
1. Why do you think we are not
ranked top in the world?
Migration: a factor in population
change.
• Migration is mostly driven by economic
desires
1. movement of people into/out of specific
geographical locations
• Other reasons for migration:
1. Religious persecution
2. Political oppression
3. Ethnic conflicts
4. Environmental degradation
Case Study: The United States
- A Nation of Immigrants
• Immigration – (legal and illegal) account
42% of population growth
• 1820–1960: Most immigrants came
from Europe
• Since 1960:
– Latin America – 53%
– Asia – 25%
– Europe – 14%
Case Study: The United States
- A Nation of Immigrants
• Opponents of immigration:
1. Concerns of attracting the worlds poor
2. Stabilize population sooner
3. Reduce growing environmental impact
4. 60% of population favor reducing immigration
• Proponents of immigration:
1. US holds important historical role
2. Immigrants will do menial jobs, and pay taxes
3 Add cultural vitality
4. Replace retiring baby boomers
Sect 6.3: How Does a Population’s
Age Structure Affect Its Growth or
Decline?
• Concept to learn in sect. 6-3: The
numbers of males and females in
young, middle, and older age groups
determine how fast populations grow
or decline.
Age Structure description:
• Distribution of population
– Prereproductive (0-14)
– Reproductive (15-44)
– Postreproductive (45+)
• Countries with many young people grows
rapidly
• Countries with many older people will decline
• Developing countries: >30% under 15 years
old (greater than1 in every 4 persons)
Age Structure Predicts the Future
for a Country’s Population
• 36% of U.S. population are baby boomers
• By 2029, we will experience the “Graying
of America”
1. Between now and 2029, we will have an
increasing percentage of older baby
boomers
2. What changes would you expect as
this takes place?
Declines That will Occur in an
Aging Population:
• A sudden & rapid decline in birth rate can
lead to “Baby bust” or “birth dearth” 1. a
prolonged TFR below 1.5 children per couple
2. Can lead to:
a. Labor shortages
b. Strain on governments for public
services (like social security & medicare)
c. Fewer working taxpayers
• Japan has world’s highest % of elderly
•
Declines from disease: “Rising
Death Rate: The AIDS
Tragedy”
Large #s of deaths from AIDS will disrupt social and
economic structure
1. It removes productive young adults from its age
structure
a. Lose trained workers, children orphaned
• 1981-2008: 27 million deaths have occurred from
AIDS
• Eight African countries: 16–39% infected adults
1. Their life expectancy: 30–40 years
Sect. 6-4: How Can We Slow
Human Population Growth?
• Concept to learn in sect. 6-4: We can
slow population growth by reducing
poverty, encouraging family planning,
and elevating the status of women.
How Can We Slow Human
Population Growth?
• 1. Promote economic development
• 2. Promote family planning
• 3. Empower women
Stages of Demographic
Transition
• Demographic Transition: a hypothesis of
population change that states that as a
country becomes industrialized, their
population growth will slow down.
• Countries are categorized as:
1. Preindustrial
2. Transitional
3. Industrial
4. Postindustrial
Family Planning: a way of
controlling population growth
• Provides education about birth spacing,
birth control, & available health care
• Increased availability of contraception
• Is responsible for a 55% drop in TFR of
developing countries
1. Developing countries:
a. Almost half pregnancies unplanned
b. Often lack access to family planning
Family Planning
• Countries are “investing” in family
planning ($1 spent $10-16 in savings
on education, health, etc costs)
• Japan & China have shown that
population growth can be reduced thru:
1. Reducing poverty
2. Elevating the social and economic status
of women
3. Encouraging family planning
Empowering Women Can Slow
Population Growth
• Women tend to have fewer children if
they:
1. Are educated
2. Control their own fertility
3. Have a paying job outside the home
4. Do not have their rights suppressed
• Most women are “trapped”, and purposely
limited from being empowered.
Empowering Women Can Slow
Population Growth
• Women do almost all the worlds
domestic housework and childcare
• Women do 60-80% of all agriculture
(food growth), wood gathering, & water
hauling
• Globally, women do 2/3 of all the work
for only 10% of earned income.
Empowering Women Can Slow
Population Growth
• Illiterate women account for 64% of
world’s population, and 70% of the poor
• Women own only 2% of land
• When daughters considered less
valuable, they are often not sent to
school
• Poor conditions for women leads to
environmental degradation
Case Study: Slowing Population
Growth in China
• 1960’s: China’s population was growing so
rapidly, it caused a serious threat of mass
starvation, which lead to governmental laws:
1. One-child families
2. Halved birth rate and drastically reduce
TFR (from 5.7 to 1.6)
3. Improved quality of life
4. Strict family planning
5. Sons are still preferred – leading to a
gender imbalance (and a “bride” shortage)
Case Study: Slowing Population
Growth in China
• Population rapidly aging
1. will probably lead to less restrictions
in the one child/family laws
• Rapidly growing economy (3rd in world)
• Have a growing middle class (increases
resource consumption and waste)
• A sustainable economic plan is needed
to avoid environmental degradation
Case Study: Slowing Population
Growth in India
• Tried to slow population growth for five
decades!
• Is projected to be the most populous country
in 2015
• Problems increase with growing population:
1. Poverty
2. Malnutrition
3. Environmental degradation
4. Growing middle class leads to an increased
resource consumption
Controlling population size thru
controlling migration & family planning
• Controversial.
1. Faith often plays a part.
2. Beliefs in our countries founding
principles may play a part.
3. What is your opinion? Should
there be more control? Less
control? Take a moment to think
about this.
Sect. 6-5: What Are the Major Urban
Resource Environmental Problems?
• Concept to learn in sect. 6-5: Most
cities are unsustainable because of
high levels of resource use, waste,
pollution, and poverty.
Urban Living
•
•
•
•
Half the world lives in urban areas
79% of Americans live in cities
50% of world population lives in cities
Urban areas continue to grow:
1. By natural increase (births over deaths)
2.By immigration from other areas.
a. For jobs, freedoms, etc.
3. Urban area = 1 million + people.
4 Major Trends in Urban Growth:
1. Proportion of urban global population is growing
2. Number and sizes of large urban areas is
mushrooming
a. Megacity = 10 million + people
b. Hypercity = 20 million + people
c. There is a rapid increase in urban populations in
developing countries
3. Urban growth slower in developed nations
• Poverty is increasing in urban areas of developing
countries.
Case Study: Urbanization in the
United States
• 1800–2009: urban population increased
from 5% to 79%
• 4 phases of migration patterns in US:
1. From rural areas to large cities
2. From large cities to suburbs and smaller
cities
3. From cities and suburbs to rural areas
4. From the North and East to South and
West (like Florida, Nevada, Arizona)
Case Study: Urbanization in the
United States
• There are better working and housing
conditions compared to the past
1. lead to lower death rates
• Improved environmental conditions
1. our biodiversity is better protected
• Problems in urban areas
– Aging infrastructure (bridges, sewers, etc)
– Budget problems (due to declining tax
base)
Urban Sprawl
• Urban Sprawl: the growth/development on
the edges of cities & towns.
1. Causes:
a. Prosperity
b. Ample and affordable land
c. Automobiles
d. Availability of cheap gasoline
e. Poor urban planning
Urban Sprawl Effects on the
Environment:
• Increased automobile use
1. Effect?
• Decreased energy efficiency, requiring
greater use of resources.
• Destruction of cropland, forests, wetlands
• Economic deaths of some cities
1. Businesses will move from city into urban
sprawl areas.
Urban Sprawl Benefits:
•
•
•
•
•
Larger lot sizes for single family homes
Newer schools
Lower crime rates than in the city
Less congestion and traffic
Can take advantage of city opportunities
without disadvantages of city living.
• Do the advantages of Urban Sprawl
outweigh it’s disadvantages/
Advantages of Urbanization
• Greater economic development & job
opportunities
• More innovation
• Better education opportunities
• More technological advances
• Longer life spans than in rural areas. (more
so for the rich than the poor)
• Save energy by using mass transportation
Advantages of Urbanization
• Better social and medical services
• Recycling more feasible
• Biodiversity increased
Disadvantages of Urbanization
• Most of worlds cities are unsustainable
systems. Why?
• Lack of vegetation
1.What does vegetation do for the
environment?
• Water problems:
1. Need more! It has to come from
somewhere!
• Pollution (more in smaller area)
Disadvantages of Urbanization
• Noise pollution
• Climate and artificial light (interfere with
some plant & animal species)
1. climates are worse in urban areas. Why?
• Urban heat islands
• Light pollution
• Flooding, due to lack of impervious surfaces.
• Health problems: quick spread of infectious
diseases.
Urban Poor in Developing
Countries
• Slums
• Shantytowns and squatter
settlements
• Lack of basic services
Case Study: Mexico City
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•
•
•
•
•
Large population
Severe noise, water, and air pollution
50% unemployment
100,000 premature deaths per year
Most live in slums called “barrios”
Lack basic necessities, like running
water & electricity
Case Study: Mexico City
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•
•
•
3 million without sewer
Fecal snow
Geography contributes to air pollution
Progress:
1. tree planting has lowered air
pollution
2. restricted car use
6-6 How Does Transportation Affect
Urban Environmental Impacts?
• Concept to learn in sect. 6-6: In
some countries, most people live in
dispersed urban areas and depend
mostly on motor vehicles for their
transportation.
Cities Can Grow Outward or
Upward
• Compact cities:
1. Transportation is mostly by walking,
biking, or mass transit
2. Examples: Hong Kong, Tokyo
• Dispersed cities:
1. Transportation is mostly by automobile
2. Most American cities
Automobiles: The
Disadvantages
• Gas guzzlers
• 40,000 people per year die from auto
accidents in the United States
• World’s largest source of air pollution
• Lead to urban sprawl and congestion
Reduce Automobile Use
• User-pays system (Like in Europe)
1. they pay $10-$15 per gallon, which is
mostly tax.
• “Full-cost pricing” means that we would pay
for all the costs incurred due to auto pollution
by placing a tax on gas
• Tax revenues to finance mass transit, bike
paths, sidewalks
• High gasoline tax unlikely in US (Why?)
Alternatives to Cars
• Need to discourage automobile use
1. Bicycles
2. Mass transit systems in urban
areas
3. Bus systems
4. Rapid rail
6-7 How Can Cities Become
More Sustainable and Livable?
• Concept to learn in Sect. 6-7: An
ecocity allows people to choose
walking, biking, or mass transit for
most transportation needs; recycle or
reuse most of their wastes; grow
much of their food; and protect
biodiversity by preserving surrounding
land.
Environmentally Sustainable
Cities
• Smart growth
• Ecocities
– Use renewable energy as much as possible
– Build and design people-oriented cities
– Use energy and matter efficiently
– Prevent pollution and reduce waste
– Recycle, reuse, and compost
– Protect and encourage biodiversity
– Promote urban gardens and farmers markets
– Zone for environmentally stable population
levels
Case Study: Curitiba, Ecocity in
Brazil
• Curitiba – “ecological capital” of
Brazil
• Inexpensive, efficient mass transit
• High-rise apartments near bus routes,
mixed-use structures
• Bike and pedestrian paths
Case Study: Curitiba, Ecocity in
Brazil
•
•
•
•
1.5 million trees planted
Recycling
Many services for the poor
Emphasis on ecological awareness,
health, literacy
Three Big Ideas from This
Chapter - #1
The human population is increasing
rapidly and may soon bump up
against environmental limits.
Three Big Ideas from This
Chapter - #2
We can slow human population growth
by reducing poverty, encouraging
family planning, and elevating the
status of women.
Three Big Ideas from This
Chapter - #3
Most urban areas, home to half of the
world’s people, are unsustainable,
but they can be made more
sustainable and livable within your
lifetime.