Chapter 6

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

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 into almost all of the planet’s climate zones and habitats.
– The emergence of early and modern agriculture allowed us to grow more food for each unit of land area farmed.
– Death rates dropped sharply because of improved sanitation and health care.

Human population growth continues but it is unevenly distributed
• The rate of population growth has slowed, but the world’s population is still growing at a rate that added about 83 million people during 2011.
• Geographically, growth is unevenly distributed.
– About 1% of the 83 million new arrivals on the planet in
2011 were added to the world’s more-developed countries
– The other 99% were added to the world’s middle- and low-income, less-developed countries. At least 95% of the 2.6 billion people likely to be added to the world’s population between 2011 and 2050 will end up in the least-developed countries.

2.5
2.0
1.5
1.0
0.5
0.0
1950 1970 1990
Year
2010 2030 2050
Fig. 6-2, p. 97

Human population growth continues but it is unevenly distributed
• 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.

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

The human population can grow, decline, or remain fairly stable
• Birth rate, or crude birth rate, is the number of live births per 1,000 people in a population in a given year.
• Death rate, or crude death rate, is the number of deaths per 1,000 people in a population in a given year.
• Population change of an area = (births + immigration) - (deaths + emigration)

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, the average global lifetime number of births of live babies per woman dropped from 5 to 2.5.
• A TFR of 2.1 will eventually halt the world’s population growth.

4.0
3.5
3.0
2.5
2.1
2.0
1.5
1.0
0.5
0
1920
Baby boom
(1946 –64)
Replacement level
1930 1940 1950 1960
Year
1970 1980 1990 2000 2010
Fig. 6-3, p. 98

Life expectancy
Married women working outside the home
High school graduates
8%
15%
Homes with flush toilets
Homes with electricity
2%
10%
People living in suburbs
10%
Hourly manufacturing job wage
$3
Homicides per
100,000 people
1.2
47 years
77 years
81%
52%
$15
5.8
83%
98%
99%
1900
2000
Fig. 6-4, p. 99

• A particular country’s average birth rate and TFR can be affected by:
– The importance of children as a part of the labor force.
– The cost of raising and educating children.
– The availability of, or lack of, private and public pension systems.
– Urbanization.

– The educational and employment opportunities available for women.
– The average age at marriage.
– The availability of legal abortions.
– The availability of reliable birth control methods.
– Religious beliefs, traditions, and cultural norms.

• People started living longer and fewer infants died because of increased food supplies and distribution, better nutrition, medical advances, improved sanitation, life expectancy, married women working, and safer water supplies.
• 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.

– Infant mortality is a measure of a society’s quality of life because it reflects the general level of nutrition and health care. A high infant mortality rate can results from insufficient food (undernutrition), poor nutrition (malnutrition), and a high incidence of infectious disease, which is exacerbated by under- or malnutrition.
– 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:
• inadequate health care for poor women during pregnancy and for their babies after birth
• drug addiction among pregnant women
• a high teenage pregnancy rate

• Migration is the movement of people into
(immigration) and out of (emigration) specific geographic areas.
– Most people who migrate from one country to another are seeking jobs.
– Religious persecution, ethnic conflicts, political oppression, wars, and certain types of environmental degradation are also factors.
– Environmental refugees are people who migrate due to environmental degradation such as soil erosion and water and food shortages. One UN study estimated that a million people are added to this category every year.

• 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 Europe. Since
1960, most have come from Latin America and
Asia. Hispanics are projected to make up 30% of the U.S. population by 2050.

• There is controversy over reducing legal immigration to the U.S.
– Proponents of reducing immigration say it would help stabilize population size and reduce the country’s enormous environmental impact.
– Those against say it would diminish the role of the
U.S. as a land of opportunity and take away from cultural diversity and innovation. Most immigrants and their descendants start new businesses and create jobs. Many immigrants take menial and lowpaying jobs that most other Americans shun.

• There were an estimated 11 million illegal immigrants in the United States in 2011. There is controversy over what to do about illegal immigration.
– Some want to deport all illegal immigrants.
– Others want to set up programs that allow illegal immigrants to remain in the country as long as they are working towards citizenship.

2,000
1,800
1,600
1,400
1,200
1,000
800
600
400
1907
1914
New laws restrict immigration
Great
Depression
200
0
1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2010
Year
Fig. 6-6, p. 101

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

• Age structure is the numbers or percentages of males and females in young, middle, and older age groups in a given population.
• Population age-structure diagrams are made by plotting the percentages or numbers of males and females in the total population in each of three age categories:
– Prereproductive (0–14): normally too young to have children.
– Reproductive (15–44): normally able to have children.
– Postreproductive (45+): normally too old to have children.

• Demographic momentum is rapid population growth in a country that has a large percentage of people younger than 15, and happens when a large number of girls enter their prime reproductive years.
• 1.8 billion people will move into their reproductive years by 2025.
• Most future human population growth will take place in less-developed countries due to their population age structure.
• The global population of seniors (age 65 and older) is increasing due to declining birth rates and medical advances that have extended life spans.

Less-developed
Countries
Male Female
More-developed
Countries
Male Female Male Female Male Female
Expanding Rapidly
Guatemala, Nigeria
Saudi Arabia
Prereproductive ages
0
–14
Expanding Slowly
United States
Australia, China
Reproductive ages
15
–44
Stable
Japan, Italy
Greece
Declining
Germany, Bulgaria
Russia
Postreproductive ages 45 –85+
Fig. 6-7, p. 102

• Added 79 million people to the U.S. population 1946-1964.
• The large numbers of baby boomers have strongly influenced the U.S. economy. First they created a youth market and are now creating the late middle age and senior markets.
• As the baby boomers turn 65, the number of seniors will grow sharply through 2030. This process has been called the graying of America.
• As the number of working adults declines in proportion to the number of seniors, so will the tax revenues necessary for supporting the growing senior population.

• 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.
• The average age of China’s population is increasing at one of the fastest rates ever recorded. This could lead to a declining work force, higher wages for workers, limited funds for supporting continued economic development, and fewer children and grandchildren to care for the growing number of elderly people.

Populations can decline from a rising death rate: the AIDS tragedy
• Between 1981 and 2010, AIDS killed more than 29 million people, and it takes about 2 million more lives each year (22,000 in the United States).
• AIDS kills many young adults and leaves many children orphaned, causing a change in the youngadult age structure of a country. This causes a sharp drop in average life expectancy, especially in several African countries where 15 –26% of the adult population is infected with HIV.
• AIDS can cause a pandemic loss of productive young adult workers and trained personnel.

Some Problems with Rapid Population Decline
Can threaten economic growth
Labor shortages
Less government revenues with fewer workers
Less entrepreneurship and new business formation
Less likelihood for new technology development
Increasing public deficits to fund higher pension and health-care costs
Pensions may be cut and retirement age increased
Fig. 6-9, p. 103

100+
95 –99
90 –94
85 –89
80 –84
75 –79
70 –74
65 –69
60 –64
55 –59
50 –54
45 –49
40 –44
35 –39
30 –34
25 –29
20 –24
15 –19
10 –14
5 –9
0 –4
Males Females
120 100 80 60 40 20 0 20 40 60 80 100 120
Population (thousands)
With AIDS Without AIDS
Fig. 6-10, p. 104

Section 6-4
HOW CAN WE SLOW HUMAN
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.

80
70
60
50
40
30
20
10
0
Stage 1
Preindustrial
Population grows very slowly because of a high birth rate (to compensate for high infant mortality) and a high death rate
Low Increasing
Stage 2
Transitional
Population grows rapidly because birth rates are high and death rates drop because of improved food production and health
Birth rate
Total population
Death rate
Very high Decreasing
Growth rate over time
Stage 3
Industrial
Population growth slows as both birth and death rates drop because of improved food production, health, and education
Low
Stage 4
Postindustrial
Population growth levels off and then declines as birth rates equal and then fall below death rates
Zero Negative
Fig. 6-11, p. 105

• As countries become industrialized and economically developed, their populations tend to grow more slowly. This demographic transition has four phases:
– Preindustrial
– Transitional
– Industrial
– Postindustrial

• Less-developed countries may transition to slower growth if modern technology can raise per capita incomes by bringing economic development and family planning.
• Rapid population growth, extreme poverty, and increasing environmental degradation in some low-income less-developed countries — especially in Africa —could leave these countries stuck in stage 2 of the demographic transition.

• 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 children in societies where almost all women can read.

• Family planning provides educational and clinical services that help couples choose how many children to have and when to have them.
• 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.

• Problems that have hindered success in some countries:
– 42% of all pregnancies in less-developed countries are unplanned and 26% end with abortion.
– An estimated 201 million couples in lessdeveloped countries want to limit their number of children, but lack access to family planning services.

• For over 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: even though 9/10 Indian couples have access to at least one modern birth control method, only 48% actually use one.

Four of every ten people in India struggle to live on the equivalent of less than $1.25 /day

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

• An increasing percentage of the world’s people live in urban areas.
• Urban areas grow in two ways—by natural increase due to births and by immigration, mostly from rural areas.
• Three major trends in urban population dynamics have emerged:
– 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.

– The numbers and sizes of urban areas are mushrooming. We now have cities with 10 million or more people (megacities or megalopolises) and will soon have hypercities with more than 20 million people. Megacities and hypercities are merging into megaregions that can stretch across entire countries.
– Poverty is becoming increasingly urbanized, mostly in less-developed countries. An estimated 1 billion people in less-developed countries live in urban slums and shantytowns.

Los Angeles
15.2 million
Mexico City
20.5 million
Moscow
15 million
Delhi
18.6 million
Hong Kong
15.8 million
Beijing
22 million
Shanghai
17 million
London
12.9 million
Tokyo
36 million
New York
19.7 million
Lagos
Rio de Janeiro
12 million
São Paulo
18.9 million
Buenos Aires
13.1 million
Cairo
14.5 million
Karachi
12.2 million
13.4 million
Osaka
17.4 million
Seoul
20.6 million
Mumbai
(Bombay)
Manila
Kolkata
(Calcutta)
15.1 million Bangkok
12 million
16.3 million
Jakarta
Dhaka
19.2 million
13 million
18.9 million
Fig. 6-14, p. 108

• Between 1800-2011, the % of the U.S. population living in urban areas increased from 5% to 79%.
This population shift has occurred in four phases.
– People migrated from rural areas to large central cities.
– Many people migrated from large central cities to smaller cities and suburbs.
– Many people migrated from the North and East to the
South and West.
– Some people fled cities and moved to developed areas outside of suburbs. These exurbs are scattered over vast areas that lie beyond suburbs and have no socioeconomic centers.

• There are upsides to urbanization. Conditions in U.S. cities have improved, with better working and housing conditions, improved air and water quality, and decreased death rates and sickness from infectious diseases due to better sanitation, clean public water supplies, and medical care.
• Concentrating people in urban areas has helped protect the country’s biodiversity by reducing the destruction and degradation of wildlife habitat.
• Many cities have aging infrastructures (streets, bridges, dams, power lines, schools, waste management, water supply pipes, and sewers) with limited funds for repair.

1973 2009

• Urban sprawl, or the growth of low-density development on the edges of cities and towns, is eliminating surrounding agricultural and wild lands.
• Urban sprawl is the product of affordable land, automobiles, relatively cheap gasoline, and poor urban planning.

• Urban sprawl has caused or contributed to a number of environmental problems.
– People are forced to drive everywhere, resulting in more emission of greenhouse gases and air pollution.
– Sprawl has decreased energy efficiency, increased traffic congestion, and destroyed prime cropland, forests, and wetlands.
– Sprawl has led to the economic deaths of many central cities as people and businesses move out.

• Cities are centers of industry, commerce, transportation, innovation, education, technological advances, and jobs.
• Urban residents in many parts of the world tend to live longer than do rural residents, and 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.
• Concentrating people in cities helps to preserve biodiversity.
• Central cities can save energy if residents rely more on energy efficient mass transportation, walking, and bicycling.

• Most urban areas are unsustainable systems.
– The typical city depends on large non-urban areas for huge inputs of matter and energy resources, while it generates large outputs of waste matter and heat.
• Most cities lack vegetation.
– Destroyed vegetation could have absorbed air pollutants, given off oxygen, provided shade, reduced soil erosion, provided wildlife habitats, and offered aesthetic pleasure.
• Many cities have water problems.
– Providing water to cities can deprive rural and wild areas of surface water and can deplete underground water supplies.

– Cities in arid areas that depend on water withdrawn from rivers and reservoirs behind dams will face increasing problems.
– 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.

– 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.

Inputs
Energy
Food
Water
Raw materials
Manufactured goods
Money
Information
Outputs
Solid wastes
Waste heat
Air pollutants
Water pollutants
Greenhouse gases
Manufactured goods
Noise
Wealth
Ideas
Fig. 6-18, p. 110

• Cities produce most of the world’s air pollution, water pollution, and solid and hazardous wastes.
• High population densities can increase the spread of infectious diseases, especially if adequate drinking water and sewage systems are not available.

• Cities tend to be warmer, rainier, foggier, and cloudier.
• Heat generated by cars, factories, furnaces, lights, air conditioners, and heatabsorbing dark roofs and streets creates an urban heat island surrounded by cooler suburban and rural areas.
• The artificial light created by cities affects some plant and animal species.

Life is a desperate struggle for the urban poor in less-developed countries
• At least 1 billion people live under crowded and unsanitary conditions in cities in less-developed countries.
• Slums are areas dominated by tenements and rooming houses where several people might live in a single room.
• Squatter settlements and shantytowns are on the outskirts of cities, and usually lack clean water supplies, sewers, electricity, and roads, and are subject to severe air and water pollution and hazardous wastes from nearby factories.

• The world’s second most populous city suffers from severe air pollution, high unemployment, noise, overcrowding, traffic congestion, inadequate public transportation, and a soaring crime rate. More than one-third of its residents live in slums or squatter settlements that lack running water, electricity and sewage facilities.
• Air and water pollution cause an estimated
100,000 premature deaths per year.

• The severity of air pollution has been reduced by banning cars in its central zone, requiring air pollution controls on newer cars, phasing out leaded gasoline, and encouraging purchase of buses, taxis, and delivery truck that produce fewer emissions. The city also bought land for use as green space and planted more than 25 million trees to help absorb pollutants.

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

Cities can grow outward or upward
• Most people living in compact cities such as Hong Kong, China, and Tokyo, Japan, get around by walking, biking, or using mass transit such as rail or buses.
• In countries such as the United States,
Canada and Australia, plentiful land and networks of highways have produced dispersed cities whose residents depend on motor vehicles for most travel .

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.

• They provide mobility and offer convenient and comfortable transportation.
• They can be symbols of power, sex appeal, social status, and success.
• Much of the world’s economy is built on producing motor vehicles and supplying fuel, roads, services, and repairs for them.
• Globally, automobile accidents kill approximately 1.2 million people a year and injure another 15 million people.

• They kill about 50 million wild animals and family pets every year.
• Motor vehicles are the world’s largest source of outdoor air pollution.
• They are the fastest-growing source of climatechanging CO
2 emissions.
• At least a third of the world’s urban land and half of that in the United States is devoted to roads, parking lots, gasoline stations, and other automobile-related uses.
• People waste time sitting in traffic congestion.

• 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 .

• Raise parking fees and charge tolls on roads, tunnels, and bridges leading into cities, especially during peak traffic times.
• Some cities promote car-sharing networks, which bill members monthly for the time they use a car and the distance they travel, and can decrease car ownership.

• 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?

We can make urban areas more environmentally sustainable and enjoyable places to live
• Smart growth encourages environmentally sustainable development requiring less dependence on cars, controls and directs sprawl, and reduces wasteful resource use, by using zoning laws and other tools to channel growth into areas where it can cause less harm.
• New urbanism involves less-developed villages within cities, so that people can live within walking distance of where the work, shop, and go for entertainment

• Vauban is a suburb outside the city of Freiberg,
Germany that is virtually free of cars.
• Street parking, driveways, and garages are generally forbidden in the village. A parking space in a city garage costs $40,000.
• Homes are within easy walking distance of trains, stores, banks, restaurants, and schools. There are numerous bike paths and a car-sharing club. Mass transit allows residents to work or shop in the city of
Freiburg.
• There are no single-family homes, only energyefficient row houses that use passive solar energy.

• An ecocity emphasizes the following goals:
– Use solar and other locally available, renewable energy resources and design buildings to be heated and cooled as much as possible by nature.
– Build and redesign cities for people, not cars.
– Reduce the waste of matter and energy.
– Prevent pollution.
– Reuse, recycle, and compost 60–85% of all municipal solid waste.
– Protect and encourage biodiversity by preserving undeveloped land and protecting and restoring natural systems and wetlands in and around cities.
– Promote urban gardens and farmers markets.
– Use zoning and other tools to keep urban sprawl at environmentally sustainable levels.

• Current examples of ecocities include
Curitiba, Brazil; Bogotá, Colombia;
Waitakere City, New Zealand; Stockholm,
Sweden; Helsinki, Finland; Leicester,
England; Neerlands, the Netherlands; and in the United States, Portland, Oregon;
Davis, California; Olympia, Washington; and Chattanooga, Tennessee

• 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.

• 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.

• 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.

• 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.