Environment in the News

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Human Population Change and the Environment

Chapter 7

India’s Population Pressures

World’s second most populous nation
1.2 billion
1950s - government sponsored family planning
Number of children per woman declined from 5.3 (1980) to 2.7 (2009)
Despite success
Population pressure has cause environmental degradation
76% live under poverty level (less than $2 /day)

India’s Population Pressures

Learning Objectives:

Define population ecology

Explain the four factors that produce changes in population size

Define biotic potential and carrying capacity

Population Ecology

Population:
Individuals of the same species, living in the same place at the same time
Population Ecology:
Study populations’ responses to environment
Competition for food and resources; predation, disease, etc.
How environmental pressures affect population growth

Population Ecology

How Do Populations Grow in Size?
Two factors:
Birth Rate (b) = expressed as number per 1000 people/yr
Death rate (d) = expressed as number per 1000 people/yr
Growth Rate (r): rate of change of population size (natural increase)
R = b – d
If population is growing, r > 0 (d < b)
If population is shrinking, r < 0 (d > b)
If population is stable, r = 0 (d = b)

Population Ecology

Growth rate is also affected by dispersal:
Immigration (i) = individuals enter a population
Emigration (e) = individuals leave population

r = (b – d) + (i – e)

Population Ecology

Maximum Population Growth
Biotic Potential (maximum rate of increase under optimal conditions)
Life history characteristics:
Age at first reproduction
Reproductive fraction of life span
Number of reproductive periods/events
Number of offspring per reproductive event
Larger organisms tend to have smaller biotic potentials (e.g., whales)
Smaller organisms tend to have larger biotic potentials (e.g., bacteria)

Population Ecology

Population Growth Rates:
Some bacteria reproduce every 30 minutes.
1bacterium 10 million in 10 hrs1 billion in 15 hrs
Plot population number vs. time, the graph looks like a J
J-shaped growth is called exponential growth
Exponential growth
Accelerating population growth that occurs when optimal conditions allow a constant reproductive rate

Population Ecology

Environmental Resistance:
Environmental factors that limit the exponential growth of populations
Food, water, shelter, disease, predation, waste accumulation
As the environment deteriorates
population growth declines
death rate increases
The environment controls population size
As the population grows, so does environmental resistance, which limits population growth
Exponential growth is no longer possible

Population Ecology

Carrying Capacity (K):
The largest population a particular environment can support sustainably (long term), if there are no changes in that environment
At K, population growth (r) is nearly zero
Gause, 1930s ecologist, experiments with Paramecium
Limited daily amount of food, and removal of waste
At first, exponential growth, then leveled off
S-shaped curve

Population Ecology

Carrying Capacity:
Populations rarely stabilize at K
Usually, the overshoot K, then drop back below
Sometimes, there is a Population Crash
Abrupt decline from high to low numbers
Resource depletion
E.g., Reindeer crash, 1911

Population Ecology

Global Climate Change

What is population ecology?

How do each of the following affect population size: birth rate, death rate, immigration, and emigration?

How do biotic potential and/or carrying capacity produce the J-shaped and S-shaped population growth curves?

Human Population Patterns

Learning Objectives

Summarize the history of human population growth

Identify Thomas Malthus, relate his ideas on human population growth, and explain why he may or may not have been wrong

Explain why it is impossible to precisely determine how many people Earth can support—that is, Earth’s carrying capacity for humans

Human Population Patterns

Exponential growth curve of Human Population
8000 BCE to 1800 CE1 billion people
1800 to19302 billion = 130 yrs.
1930 to 19603 billion = 30 yrs
1960 to 19754 billion = 15 yrs
1975 to 19875 billion = 12 yrs
1987 to 19996 billion = 12 yrs
1999 to 2012 (projected) 7 billion

Human Population Patterns

Thomas Malthus (1766–1834)
British economist
Population can’t grow indefinitely
Consequences would be famine, war, disease
Since Malthus’ time
Human populations have continued to increase exponentially
Birth rates have not increased dramatically
Death rates have decreased dramatically
Food production has kept pace due to scientific advances
Health improvements

Human Population Patterns

Projecting Future Population Numbers
Zero population growth
The population size remains constant
Birth rate equals death rate
United Nations and World Bank experts predict we will reach ZPG by end of 21st century
By 2050, there will be 7.7–10.6 billion people
Main unknown factor: Earth’s Carrying Capacity
Estimates say Earth can support 4–16 billion
Analysis of 69 studies says 7.7 billion

Human Population Patterns

Approaching Earth’s K
What will happen to humans?
Optimists:
Birth rates will decrease, population will stabilize
Pessimists:
Environmental degradation from growing population will make Earth uninhabitable for humans and other species
Massive human suffering and death
Many experts say we have already surpassed K

Human Population Patterns

Global Climate Change

How would you describe human population growth for the past 200 years?

Who was Thomas Malthus, and what were his views on human population growth?

When determining Earth’s carrying capacity for humans, why is it not enough to just consider human numbers?

Demographics of Countries

Learning Objectives:

Define demographics and describe the demographic transition

Explain how highly developed countries differ in population characteristics such as infant mortality rate, total fertility rate, replacement-level fertility, and age structure

Demographics of Countries

Demographics:
Applied branch of sociology that deals with population statistics
Countries are grouped by
Population growth rates
Degree of industrialization
Relative prosperity
GNI PPP = gross national income in purchasing power parity
Per person GNI PPP = GNI PPP/number of people
The amount of goods and services an average citizen of a particular country could buy in the US

Demographics of Countries

Highly Developed Countries
Lowest birth rates (some have shrinking pops)
Low infant mortality rates
Longer life expectancies
Highest per capita GNI PPP
Moderately Developed Countries
Higher birth and infant mortality rates
Medium industrialization
Lower GNI PPP
Less Developed Countries
Shortest life expectancies
Highest birth and infant mortality rates

Demographics of Countries

Replacement-level Fertility Rate
The number of children a couple must produce to replace themselves
Keeps population size stable
2.1 children per woman
Total Fertility Rate
The average number of children born to each woman
Currently 2.6 children per woman

Demographics of Countries

Demographic Transition:
Stages through which a population progresses as it becomes industrialized
Four Basic Stages

Preindustrial

Transitional

Industrial

Postindustrial

Demographics of Countries

What happens when a population reaches the 4th stage?
We don’t know:
We see that TFR are dropping as countries become more industrialized
Brazil
1960 = 6.7 children/woman, 2010 = 2
Worldwide
1970 = 6.1 children/woman, 2010 = 2.7
Despite great advances, population still increasing

Demographics of Countries

Age Structure of Countries
The number and proportion of people at each age in a population
Represented in an age-structure diagram
Helps predict future population growth
Rapid growth
Slow growth
Stable
Declining
Population Growth momentum

Demographics of Countries

Growing Populations
Mostly in developing countries
82% of world’s population
Due to high population growth momentum
Great economic difficulty supporting growth
Declining Fertility Rates
Social and economic implications
Aging populations
Reduces country’s productive workforce
Increases tax burden
Strains social security and health systems
Lower violent crime rates

Demographics of Countries

Global Climate Change

What is the demographic transition?

What is infant mortality rate? How does it vary in highly developed and developing countries?

Stabilizing World Population

Learning Objectives:

Relate total fertility rates to each of the following: cultural values; social and economic status of women; the availability of family planning services; and government policies

Explain the link between education and total fertility rates

Stabilizing World Population

Reducing fertility rates to reduce

Population Growth

Cultural traditions
Women’s social and economic status
Family planning
Government policies

Stabilizing World Population

Culture and Fertility
Culture is defined (partly) by
Values and norms of a society
Varying roles men and women are expected to play
Different societies have different gender expectations
Fertility
A couple is expected to have the traditional number of children for their society

Stabilizing World Population

High TFRs are traditional in many societies
Infant and child mortality are high, but declining
Important economic and societal roles of children
218 million children under 15 yrs work full-time
Chronic health problems, no childhood, no education
As they grow, the provide for aging parents
Contrast with HDCs (highly developed countries)
Children have no value in work force, less labor is required in industrialized economy, social security provides for the elderly, so children attend school
Social pressure to produce male children
Religious values

Stabilizing World Population

Social and Economic Status of Women
Gender inequity
Lower political, social, economic, and health status of women
In developing countries, more women live in poverty than men
Not guaranteed equal legal rights, employment and earnings, education, political participation
Girls are kept home to work (instead of being sent to school) more often than boys
Higher percentage of women are illiterate

Stabilizing World Population

Single most important factor affecting high TFRs in many society is the low status of women
Marriage is the only option to achieve social status and economic security
Improving the social and economic status of women will help deal with population issues

Women with more education
Marry later and have fewer children
Reduces childbearing years, increases time between generations
Have lower infant mortality
Have more control over fertility
Children with more education have better chance at improving standard of living
Parents may choose to invest in fewer children who earn more

Stabilizing World Population

Family Planning Services
Reducing fertility can’t happen without access to health and family planning services
Prenatal care and proper birth spacing make women healthier healthier babies fewer infant deaths
Provide information on contraception
Provide contraception devices
Don’t try to limit the number of children in a family, just explain why it is better to have fewer children

Stabilizing World Population

Family Planning Services
Work best if sensitive to
Cultural and social beliefs
Role of males in the planning
(women may not want any more children but they are pressured by husbands and in-laws)
In HDCs, 68% of married women use contraceptives
In developing countries where contraceptives are available, TFRs are declining

Stabilizing World Population

What a Scientist Sees

EnviroDiscovery

Microcredit Programs

Small loans ($50–500) to very poor people to help them establish businesses and generate income
sewing machines to make clothing
used refrigerators for opening small grocery stores
FINCA (Foundation for International Community Assistance)
Not for profit agency, administers microloans
Targets women (70% of world’s poorest are women)
If mothers are employed, children benefit
Status of women is raised when they have their own income

Stabilizing World Population

Government Policies and Fertility
Involved in childbearing and childrearing
Minimum marriage age
Amount of education
Budgetary support to family planning services, education, incentives for smaller or larger family sizes
Governments of at least 78 countries have recognized they must limit population growth
Sponsor family projects
Health care, education, economic development, women’s social status

Global Climate Change

What is family planning? Is family planning effective in reducing fertility rates?

What is the relationship between fertility rate and educational opportunities for women?

Population and Urbanization

Learning Objectives:

Define urbanization and describe trends in the distribution of people in rural and urban areas

Describe some of the problems associated with rapid growth rates in large urban areas

Explain how compact development makes a city more livable

Population and Urbanization

Urbanization:
Movement of people from rural areas to densely populated cities
Approximately 79% of people in US live in cities
Cities are urban ecosystems:
Flow of energy, water, and other resources is linked to the flow of money and the human population
Political power is important in wealthy neighborhoods

Population and Urbanization

Characteristics of Cities:
Size, climate, culture, economic development
Heterogeneous population
Race, ethnicity, religion, socioeconomic status
City populations tend to be younger
Influx of younger people looking for work
Male to Female ratios
In developing countries, more males than females
In developed countries, equal

Population and Urbanization

Urban Environmental Problems
Brownfields: abandoned areas, usually contaminated from previous industries
Vacant factories, warehouses, residential sites
Result form people moving to suburban areas
Suburban Sprawl:
Suburbs expand around a city, encroaching onto natural areas and farmland
Many cities are redeveloping brownfields
Important land resources (after pollution clean-up)
New residential and commercial sites

Population and Urbanization

Transportation
Commuting is a necessity
People live in suburbs, work in city
Increases air pollution and other environmental problems
Pollution
High density of cars, factories, etc.
Buildup of airborne emissions, particulates, Sulfur oxides, carbon oxides, nitrogen oxides, VOCs
Worst urban pollution is in developing countries
Water Flow
Buildings and paved soils
No soil to absorb precipitation
Rain water becomes polluted with organic waste, motor oil, lawn fertilizer, etc.
If sewage is not treated, polluted runoff affects other water sources away from the city

Population and Urbanization

Environmental Benefits of Urbanization
Compact Development
Efficient design of cities, uses less land
Tall buildings, lots of housing on small footprint
Close to shopping and jobs
Connected by public transportation
Fewer parking lots and highways
Business development along pub. transportation lines
More open room for parks, open space, etc.
More livable and attractive to people
Portland, Oregon

Population and Urbanization

Urbanization Trends
50% of world’s population lives in urban areas
75% in HDCs
40% in developing countries
Increasing rapidly
400 cities have more than 1 million people
Megacities, more than 10 million people
Also increasing
Urban agglomerations
Urbanized core regions
Several cities or megacities and surrounding suburbs
Tokyo-Yokohama-Osaka-Kobe; 50 million people

Population and Urbanization

Urbanization Trends
Highly Developed Countries ( e.g., US)
Most migration to cities in last 150 yrs
Need for industrial labor
Slow growth, services could keep up
Water purification, sewage treatment, education, adequate housing
Developing Countries
Rapid growth - cities can’t provide basic services
Low job possibilities (still greater than in rural areas)
Substandard housing (slums)
Poverty
Unemployment
Pollution, water, and sewage issues

Population and Urbanization

Global Climate Change

Which countries are the most urbanized? The least urbanized? Which countries have the highest rates of urbanization today?

What are some of the problems caused by rapid urban growth in developing countries?

How does compact development affect city living?

Case Study

Urban Planning in Curitiba, Brazil
2.9 million people
Efficient mass transit system
High density development restricted to buss lines (72% of commuters use the bus)
Since 1970s, population has doubled, but traffic has declined 30%
Less traffic congestion
Cleaner air
“Big Sidewalk” of 49 blocks of pedestrian walkways connected to bus stops, parks, and bicycle paths
Excellent example of compact urban planning

Case Study