The Human Population and
Urbanization
Chapter 6

HOW MANY PEOPLE CAN THE
EARTH SUPPORT?
Section 6-1
Video clip…

Human population growth continues but it is unevenly distributed
• For most of history, the human population grew slowly, but has been growing exponentially for the past 200 years. Reasons for this increase in growth rate include:
– Humans have expanded...
– Green revolution…
– Death rates dropped sharply because of…

Human population growth continues but it is unevenly distributed
• The rate of population growth has slowed , but the world’s population is still growing.
• Geographically, growth is unevenly distributed.
– About 1% of the 83 million new arrivals on the planet in
2011 were added to …
– The other 99% were added to…

Annual growth of world population, 1950-2011

Human population growth continues but it is unevenly distributed
What was the carrying capacity of an ecosystem?
• Cultural carrying capacity is the maximum number of people who could live in reasonable freedom and comfort indefinitely, without decreasing the ability of the earth to sustain future generations.

WHAT FACTORS INFLUENCE
THE SIZE OF THE HUMAN
POPULATION?
Section 6-2

The human population can grow, decline, or remain fairly stable
• Birth rate , is the number of live births per 1,000 people in a population in a given year.
• Death rate , is the number of deaths per 1,000 people in a population in a given year.
• Population change of an area = ( modes of increase?
) - ( modes of decrease?
)

Women are having fewer babies but not few enough to stabilize the world’s population
• The total fertility rate (TFR) is the average number of children born to women in a population during their reproductive years.
– Between 1955 and 2011 dropped from 5 to
2.5.
– A TFR of 2.1 will eventually halt the world’s population growth.

Total fertility rates for the US between 1917-2011

Some major changes took place in the US between 1900-2000

Several factors affect birth rates and fertility rates
• A particular country’s average birth rate and TFR can be affected by:
– Child labor
– Cost of education
– Retirement
– Urbanization
– Education for women
– Age at marriage
– Abortions
– Birth control
– Religion

Several factors affect death rates
What factors affect death rates?
• Two useful indicators of the overall health of people in a country or region are life expectancy and infant mortality rate
– The average global life expectancy increased from 48 years in 1955 to 69 years in 2011. Between 1900 and
2011, the average global life expectancy in the United
States increased from 47 years to 78 years.

Child laborers in India

Several factors affect death rates
– Infant mortality is a measure of a society’s quality of life because it reflects the general level of nutrition and health care.
– While infant mortality rates in more-developed and less-developed countries have declined dramatically since 1965, more than 4 million infants die during their first year of life.
– The U.S. ranks 54 th in the world in infant mortality rates due to: Why?

Migration affects an area’s population size
• Migration is the movement of people into
(immigration) and out of (emigration) specific geographic areas.
– Work
– Religion
– Environmental
UN study found 1 million per year in this last category

CASE STUDY: The United
States: A Nation of Immigrants
• Since 1820, the United States has admitted almost twice as many immigrants and refugees as all other countries combined .
• Legal and illegal immigration account for about
36% of the country’s annual population growth.
• Between 1820 and 1960, most legal immigrants to the United States came from ________.
• Since 1960, most have come from
____________ and __________.
• Hispanics are projected to make up 30% of the
U.S. population by 2050.

CASE STUDY: The United
States: A Nation of Immigrants
• There is controversy over reducing legal immigration to the U.S.
– Pros?
– Cons?

CASE STUDY: The United
States: A Nation of Immigrants
• There were an estimated 11 million illegal immigrants in the United States in 2011. There is controversy over what to do about illegal immigration.
– Pros?
– Cons?

Legal immigration to the US,
1820-2006

How does a population’s age structure affect its growth or decline?
Section 6-3

A population’s age structure helps us to make projections
• Age structure is the numbers or % of males and females in various age groups in a given population.

The baby-boom generation in the US, 1955, 1985, and 2035

Populations made up mostly of older people can decline rapidly
• Japan has the world’s highest % of elderly people and the world’s lowest % of young people.
– Due to its discouragement of immigration, it may face a bleak economic future.
How does China compare?

Rapid population decline can cause several problems

Two projected age structures for
Botswana’s population in 2020

HOW CAN WE SLOW HUMAN
POPULATION GROWTH?
Section 6-4

There are three effective ways to slow population growth
• The three most effective ways to slow or stop population growth are:
– Reduce poverty
– Elevate the status of women
– Encourage family planning and reproductive health care.

The demographic transition

Empowering women can slow population growth
• Women tend to have fewer children if they are educated, have the ability to control their own fertility, hold a paying job outside the home, and live in societies that do not suppress their rights.
– Women account for 66% of all hours worked but receive only 10% of the world’s income and own just 2% of the world’s land.
– Women make up 70% of the world’s poor and 64% of its 800 million illiterate adults.
– Poor women who cannot read often have an average of 5 – 7 children, compared to 2 or fewer when nearly all women can read.

Women of a village in Burkina
Faso

Promote family planning
• Successes of family planning:
– Without family planning programs that began in the
1970s, the world’s population would be about 8.5 billion instead of the current 7 billion.
– Family planning has reduced the number of abortions performed each year and decreased the numbers of mothers and fetuses dying during pregnancy.

Promote family planning
• Problems that have hindered success in some countries:
– 42% of all pregnancies in less-developed countries are unplanned and 26% end with abortion.
– Lack access to family planning services.

CASE STUDY: Slowing
Population Growth in India
• 50+ years, India has tried to control its population growth with only modest success.
• Two factors help account for larger families in India.
– Most poor couples believe they need several children to work and care for them in old age.
– The strong cultural preference for male children means that some couples keep having children until they produce one or more boys.
• The result: 90% Indian couples have birth control only 48% actually use one.

40% of Indians struggle to live on the equivalent of less than $1.25 /day

WHAT ARE THE MAJOR URBAN
RESOURCE AND ENVIRONMENTAL
PROBLEMS?
Section 6-5

Scientists see three important urban trends
• An increasing % of the world’s people live in urban areas.
• Urban areas grow in two ways— ?
and ?
.
• Three major trends in urban population dynamics have emerged:
1) The proportion of the global population living in urban areas increased from 2% in 1850 to 50% today, and is projected to be 70% by 2050 .

Scientists see three important urban trends
2) We now have cities with 10 million or more people ( megacities ) and will soon have hypercities with more than 20 million people, and they are merging into megaregions that can stretch across entire countries.
3) Poverty is becoming increasingly urbanized

Major urban areas throughout the world – city lights at night

Urban areas in the US with more than 1 million people

Urban sprawl in and around Las
Vegas, NV, 1973 and 2009
1973 2009

Urban sprawl gobbles up the countryside
• Urban sprawl is…
• Urban sprawl is the product of …

Urban sprawl

Urbanization has advantages
• Cities are centers of...
• Urban residents live longer, have lower infant mortality and fertility rates.
• Cities provide better access to medical care, family planning, education, and social services.
• Recycling is more economically feasible.
• Helps to preserve biodiversity.
• Energy efficient mass transportation, walking, and bicycling.

Urbanization has disadvantages
• Most urban areas are unsustainable systems.
• Most cities lack vegetation.
• Many cities have water problems.

Urbanization has disadvantages
• Cities in arid areas that depend on water withdrawn from rivers and reservoirs
• Cities can have flooding problems for several reasons:
• Being built on floodplains or near low-lying coastlines.
• Covering land with buildings, asphalt, and concrete causes precipitation to run off quickly and overload storm drains.

Urbanization has disadvantages
– Destroying or degraded large areas of wetlands that have served as natural sponges to help absorb excess storm water.
– Flooding as sea levels rise because of projected climate.
• Cities in arid areas that depend on water bodies fed by mountaintop glaciers will face water shortages if global warming melts the glaciers.

Urban areas are rarely sustainable systems

Problems with cities…
• Cities tend to concentrate pollution and health problems
• Cities affect local climates

HOW DOES TRANSPORTATION
AFFECT URBAN
ENVIRONMENTAL IMPACTS?
Section 6-6

Cities can grow outward or upward
• Largely because of urban sprawl, all
Americans combined drive about the same distance each year as the total distance driven by all other drivers in the world, and in the process use about 43% of the world’s gasoline.

Motor vehicles have advantages and disadvantages
Like what?!?

Alternatives to cars

Reducing automobile use is not easy, but it can be done
• A user-pays approach makes drivers pay directly for most of the environmental and health costs caused by their automobile use.
– An example of full-cost pricing is a tax on gasoline that covers the estimated harmful costs of driving.
– Gasoline revenues could be used to help finance alternatives to cars.
– Taxing gasoline heavily would be difficult in the U.S. for several reasons.
• Strong opposition from the public, and from transportationrelated industries.
• The dispersed nature of most U.S. urban areas.
• Lack of fast, efficient, reliable, affordable mass transit options .

Some cities promote alternatives to cars
• The following are alternatives to cars, each with its own advantages and disadvantages:
– Bicycles
– Mass-transit rail systems in urban areas
– Bus systems in urban areas
– High-speed rail systems between urban areas
(bullet trains)

Section 6-7
HOW CAN CITIES BECOME
MORE SUSTAINABLE AND
LIVABLE?

Smart growth tools

Bus rapid-transit (BRT) system in Curitiba, Brazil

CASE STUDY: The ecocity concept in Curitiba, Brazil
• A city of 3.2 million people known as the “ecological capital” of Brazil.
• Planners in this city in 1969 focused on an inexpensive and efficient mass transit system rather than on the car.
• Only high-rise apartment buildings are allowed near major bus routes, and each building must devote its bottom two floors to stores, reducing the need for residents to travel.
• Cars are banned from the downtown area, which has a network of pedestrian walkways connected to bus stations, parks, and bicycle paths running throughout most of the city.

CASE STUDY: The ecocity concept in Curitiba, Brazil
• The city transformed flood-prone areas along its six rivers into a series of interconnected parks.
• Curitiba recycles roughly 70% of its paper and 60% of its metal, glass, and plastic. Recovered materials are sold mostly to the city’s more than 500 major industries, which must meet strict pollution standards.
• The poor receive free medical and dental care, child care, and job training, and 40 feeding centers are available for street children.
• About 95% of Curitiba’s citizens can read and write and
83% of its adults have at least a high school education.
All school children study ecology.

Three big ideas
• The human population is increasing rapidly and may soon bump up against environmental limits.
• We can slow human population growth by reducing poverty, encouraging family planning, and elevating the status of women.
• Most urban areas are unsustainable, but they can be made more sustainable and livable within your lifetime.