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The human population and its impact chapter 6 miller and spoolman 2010

The Human Population and Its ImpactChapter 6 (Miller and Spoolman, 2010)

Figure 6.1

Crowded street in China. Together, China and India have 36% of the world’s population and the resource use per person in these countries is projected to grow rapidly as they become more modernized (Case Study, p. 15).


Core case study are there too many of us 1

Core Case Study: Are There Too Many of Us? (1)

  • 1.6 million added each week.

    • Estimated 2.4 billion more people by 2050

    • Can world provide adequate standard of living w/o causing widespread environmental damage?

  • Some analysts: already too many collectively degrading earth’s natural capital

    • Is it the 82% of pop in developing countries?

    • High resource consumption in developed countries?

  • Other analysts: technology has allowed us to overcome the environmental resistance that all populations face

    • Can we continue to rely on technological innovation?


Core case study are there too many of us 2

Core Case Study: Are There Too Many of Us? (2)

  • Views on population regulation

    • Violation of religious and moral beliefs

    • Intrusion into privacy and freedom

  • Proponents of slowing/stopping growth

    • Already not providing basic needs for 1 in 5 (1.4 billion)

    • Warn of serious consequences

      • Death rates increase because of declining environmental conditions (already seen in Africa)

      • Resource use & environmental degradation increase in developed and rapidly developing countries  increased environmental stresses:

        • Infectious diseases, Biodiversity losses, Water shortages, Traffic congestion, Pollution of the seas, Climate change


6 1 how many people can the earth support

6-1 How Many People Can the Earth Support?

Concept 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 for humans and many other species.


Human population growth continues but it is unevenly distributed 1

Human Population Growth Continues but It Is Unevenly Distributed (1)

  • Three major factors account for increase in pop size:

    • Movement into new habitats and climate zones

    • Early and modern agriculture methods

    • Control of infectious diseases through

      • Sanitation systems

      • Antibiotics

      • Vaccines

  •  decreased death rates and increased birth rates


Figure 4 supplement 3 population timeline 10 000 b c 2008

Figure 4 (Supplement 3) Population timeline, 10 000 B.C.-2008


Human population growth continues but it is unevenly distributed 2

Human Population Growth Continues but It Is Unevenly Distributed (2)

  • Rate of pop growth has slowed, but still exponential—1.22% annually.

    • 82 million added in 2008, or 225,000/day

  • Growth is unevenly distributed globally.

    • In 2008, 1.2 million added in developed countries (i.e., GR, 0.1% annually)

    • 80.8 million added to developing countries (i.e., GR, 1.5% annually)

  • Projected pop size: between 7.8 and 10.7 billion

    • Depends on avg. # of babies women are likely to have.

    • 97% of this growth will occur in developing countries where there is acute poverty.


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.2Global connections: UN world population projections, assuming that by 2050 women will have an average of 2.5 children (high), 2.0 children (medium), or 1.5 children (low). The most likely projection is the medium one—9.3 billion by 2050. (Data from United Nations).


Human population growth continues but it is unevenly distributed 3

Human Population Growth Continues but It Is Unevenly Distributed (3)

  • In this century, J-shaped growth will shift to logistic S-shaped because of various factors that limit growth.

  • How many people can the earth support indefinitely?

    • Some say 2 billion

    • Others, 30 billion

    • With current food production, only 10 billion

  • Perhaps a better question: What is the optimum sustainable population?

    • Cultural carrying capacity – optimum level that would allow most to live in reasonable comfort and freedom without impairing the ability of the planet to sustain future generations.


Science focus how long can the human population keep growing

Science Focus: How Long Can the Human Population Keep Growing?

  • Humans have altered 83% of the earth’s land surface with the help of technology to meet our growing needs and wants.

  • Can the human population grow indefinitely?

    • Studies of other species show that no pop can grow indefinitely.

    • How long can we continue to increase earth’s carrying capacity by sidestepping many factors that sooner or later limit the growth of any population?

  • Thomas Malthus and population growth: 1798

  • No one knows how close we are to environmental limits.

    • Mounting evidence suggests that we are degrading the natural capital that keep us and other species alive and supports our economies.


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.AMajor ways in which humans have altered the rest of nature to meet our growing population’s resource needs and wants. Questions: Which three of these items do you believe have been the most harmful? Explain. How does your lifestyle contribute directly or indirectly to each of these three items?


6 2 what factors influence the size of the human population

6-2 What Factors Influence the Size of the Human Population?

Concept 6-2A Population size increases because of births and immigration and decreases through deaths and emigration.

Concept 6-2B The average number of children born to women in a population (total fertility rate) is the key factor that determines population size.


The human population can grow decline or remain fairly stable

The Human Population Can Grow, Decline, or Remain Fairly Stable

  • Human populations of countries and cities grow or decline through the interplay of three factors.

    • Births (fertility)

    • Deaths (mortality)

    • Migration

  • Population change = (births + immigration) – (deaths + emigration)

  • Crude birth rate – the number of live births per 1000 people in a population in a given year.

  • Crude death rate – number of death per 1000 people in a population in a given year.


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.3Global connections: the world’s 10 most populous countries in 2008, with projections of their population sizes in 2025. (Data from World Bank and Population Reference Bureau)


Women having fewer babies but not few enough to stabilize the world s population 1

Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population (1)

Another measurement used in population studies is fertility rate—the number of children born to a woman during her lifetime.

Two types of fertility rates affect a countries population size and growth rate.


Women having fewer babies but not few enough to stabilize the world s population 2

Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population (2)

  • Replacement-level fertility rate – the average number of children that couples in a population must bear to replace themselves.

    • 2.1 in developed, as high as 2.5 in some developing countries.

    • If all couples had an average of only 2.1 children, they would not be contributing to pop growth.

    • But if all of today’s girl children also have 2.1 children, the world’s pop would continue to grow for 50 more years.

  • Total fertility rate (TFR) – the average number of children born to women in a population during their reproductive years.

    • 1.6 in developed countries (down from 2.5 in 1950)

    • 2.8 in developing countries (down from 6.5 in 1950)


Case study the u s population is growing rapidly

Case Study: The U.S. Population Is Growing Rapidly

  • There has been an overall drop in TFR and birth rates (Figures 6-4 and 6-5), though population is still growing faster than an other developed country.

  • From 1900 to 2008, pop increase fourfold from 76 to 304 million.

    • Projections: 430 million by 2050; 571 million, 2100.

      • In contrast, population growth in other developed countries has slowed.

    • High per capita ecological footprint by each new addition  enormous environmental impact.

  • Some amazing changes took place in the 20th century (Figure 6-6), which led to dramatic increases in per capita resource use.


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.4Total fertility rates for the United States between 1917 and 2008. Question: The U.S. fertility rate has declined and remained at or below replacement levels since 1972, so why is the population of the United States still increasing? (Data from Population Reference Bureau and U.S. Census Bureau)


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.5Birth rates in the United States, 1910–2008. Use this figure to trace changes in crude birth rates during your lifetime. (Data from U.S. Bureau of Census and U.S. Commerce Department)


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.6Some major changes that took place in the United States between 1900 and 2000. Question: Which two of these changes do you think were the most important? (Data from U.S. Census Bureau and Department of Commerce)

See p. 127, 2nd to last paragraph for other changes.


Several factors affect birth rates and fertility rates 1

Several Factors Affect Birth Rates and Fertility Rates (1)

Children as part of the labor force

Cost of raising and educating children

Availability of private and public pension

Urbanization

Educational and employment opportunities for women


Several factors affect birth rates and fertility rates 2

Several Factors Affect Birth Rates and Fertility Rates (2)

Infant mortality rate – the number of children per 1000 live births who die before one year of age.

Average age of a woman at birth of first child

Availability of legal abortions

Availability of reliable birth control methods

Religious beliefs, traditions, and cultural norms


Several factors affect death rates 1

Several Factors Affect Death Rates (1)

  • Two useful indicators of overall health of people in a country or region:

    • Life expectancy – Average number of years a newborn can be expected to live.

      • Globally, increased from 48 to 69 from 1955 to 2008

      • In US, same years, 47 to 78

      • In poorest countries, currently 49 or less.

    • Infant mortality rate – defined above

  • Why are people living longer and fewer infants dying?

    • Increased food supply and distribution

    • Better nutrition

    • Medical advances

    • Improved sanitation

    • Safer water supplies


Several factors affect death rates 2

Several Factors Affect Death Rates (2)

  • More is spent per person in US on healthcare than in any other country, yet 41 other countries have longer life expectancies. Reasons?

    • 45 million Americans lack health insurance

    • US has one of the world’s highest obesity rates.

  • Infant mortality, viewed as one of the best indicators of a societies quality of life because it reflects a country’s general level of nutrition and health care.

  • U.S. infant mortality rate high due to

    • Inadequate health care for poor women during pregnancy and their infants

    • Drug addiction among pregnant women

    • High birth rate among teenagers


Migration affects an area s population size

Migration Affects an Area’s Population Size

  • The third factor in population change is migration: the movement of people into and out of specific geographic areas.

  • Why migrate?

    • Economic improvement

    • Religious freedom

    • Political freedom

    • Wars

    • Environmental refugees

      • 25 million in 2005

      • 50 million in 2010 (?)

      • In a warmer planet, could soar to 250 million before end of century.


Case study the united states a nation of immigrants

Case StudyThe United States: A Nation of Immigrants

  • Since 1820, the US has admitted almost twice as many immigrants and refugees as all other countries combined.

    • Legal immigration rates have varied (Figure 6-7) because of changes in immigration laws and rates of economic growth.

    • Currently, legal and illegal immigration accounts for 40% of annual pop growth.

  • Historical role of immigration in the U.S.

    • A place for opportunity for the world’s poor and oppressed and as a source of cultural diversity

    • Between 1820 and 1960 most legal immigration came from Europe.

    • Since 1960, most from Latin America (53%), Asia (25%), followed by Europe (14%).


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.7Legal immigration to the United States, 1820–2003 (the last year for which data are available). The large increase in immigration since 1989 resulted mostly from the Immigration Reform and Control Act of 1986, which granted legal status to illegal immigrants who could show they had been living in the country for several years. (Data from U.S. Immigration and Naturalization Service and the Pew Hispanic Center)


Case study the united states a nation of immigrants1

Case StudyThe United States: A Nation of Immigrants

  • Polls show 60% in favor of reducing legal immigration and there is intense controversy over what to do about illegal immigration.

    • Proponents for reducing

      • Social services make US a magnet for poor

      • Allow US to stabilize population

    • Opponents against reducing

      • Diminish the historical role of immigration to US

      • 2006 study suggests that immigrants and their descendants pay taxes, take menial and low-paying jobs, add cultural vitality, and help US succeed in global economy.

      • Last paragraph of section 6-2: Interesting note regarding the maintaining of ratio of worker to retirees.


6 3 how does a population s age structure affect its growth or decline

6-3 How Does a Population’s Age Structure Affect Its Growth or Decline?

Concept 6-3 The numbers of males and females in young, middle, and older age groups determine how fast a population grows or declines.


Populations made up mostly of young people can grow rapidly 1

Populations Made Up Mostly of Young People Can Grow Rapidly (1)

  • Age structure categories – the distribution of males and females among age groups in a population.

    • Prereproductive ages

    • Reproductive ages

    • Postreproductive ages


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.8Generalized population age structure diagrams for countries with rapid (1.5–3%), slow (0.3–1.4%), zero (0–0.2%), and negative (declining) population growth rates. A population with a large proportion of its people in the prereproductive age group (far left) has a large potential for rapid population growth. Question: Which of these figures best represents the country where you live? (Data from Population Reference Bureau)


Populations made up mostly of young people can grow rapidly 2

Populations Made Up Mostly of Young People Can Grow Rapidly (2)

  • What is one of the world’s most important population statistics?

    • Nearly 28% of the people on the planet were under 15 year old in 2008.

      • That’s 1.9 billion that will move into their prime reproductive years.

      • In developing countries: 30% (41% in Africa)

      • 17% in developed countries (20% in the USA and 16% in Europe)

  • Figure 6-9 shows then where most all future population growth will come from


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.9Global outlook: population structure by age and sex in developing countries and developed countries, 2006. Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau)


We can use age structure information to make population and economic projections

We Can Use Age-Structure Information to Make Population and Economic Projections

  • Changes in a country’s age structure have long-lasting economic and social impacts.

  • The baby boom, 1946 – 1964 added 79 million people.

    • Over time this group looks like a bulge moving up though the country’s age structure (Fig. 6-10).

    • Baby boomers make up almost half of all adult Americans 

      • Dominate the population’s demand for goods and services.

      • Major influence on who gets elected and what laws are passed

      • After 2011, number of older Americans  65 years will increase from about 13% to 25% by 2043.


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.10Tracking the baby-boom generation in the United States. U.S. population by age and sex, 1955, 1985, 2015, and 2035 (projected).


Populations made up of mostly older people can decline rapidly

Populations Made Up of Mostly Older People Can Decline Rapidly

  • Slow decline

    • Manageable

  • Rapid decline

    • Severe economic and social problems

      • Puts severe strain on government budgets because these individuals consume an increasingly larger share of medical care, social security funds, and other costly public services, which are funded by a decreasing number of working tax payers.


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.11Some problems with rapid population decline. Question: Which three of these problems do you think are the most important?


Populations can decline from a rising death rate the aids tragedy

Populations Can Decline from a Rising Death Rate: The AIDS Tragedy

  • A large number of deaths from AIDS can disrupt a country’s social and economic structure by removing significant numbers of young adults from its age structure.

    • 25 million killed by 2008

    • Loss of most productive workers and trained personnel

    • Sharp drop in life expectancy

  • International community called upon to

    • Reduce the spread of HIV through education and health care

    • Financial assistance and volunteers to help compensate for the missing young-adult generation.


6 4 how can we slow human population growth

6-4 How Can We Slow Human Population Growth?

Concept 6-4 Experience indicates that the most effective ways to slow human population growth are to encourage family planning, to reduce poverty, and to elevate the status of women.


As countries develop their populations tend to grow more slowly

As Countries Develop, Their Populations Tend to Grow More Slowly

  • Demographic transition

    • Hypothesis developed by examining birth and death rates in 19th century western Europe

    • As countries become industrialized, first death rates decrease and then birth rates.

    • Four stages (Figure 6-12):

      • Preindustrial

      • Transitional

      • Industrial

      • Postindustrial

  • Modern tech and family planning in developing countries


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.12Four stages of the demographic transition, which the population of a country can experience when it becomes industrialized. There is uncertainty about whether this model will apply to some of today’s developing countries. Question: At what stage is the country where you live?


As countries develop their populations tend to grow more slowly1

As Countries Develop, Their Populations Tend to Grow More Slowly

  • Factors that hinder demographic transition:

    • Population growth to rapid, outpaces economic growth and overwhelms local life-support systems.

      • Keeps population at Stage 2—Demographic trap

    • HIV/AIDS may take countries back to Stage1.

    • Other factors

      • Shortages of scientists and engineers

      • Shortages of skilled workers

      • Insufficient financial capital

      • Large debts to developed countries

      • Decreased economic assistance from developed countries since 1985


Planning for babies works 1

Planning for Babies Works (1)

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

    • Provides information on birth spacing, birth control, and heath care for pregnant women and infants.

  • A major factor in deducing the number of birth throughout most of the world.

    • Responsible for a 55% drop in TFRs in developing countries.


Planning for babies works 2

Planning for Babies Works (2)

  • Despite success in many developing countries in reducing TFRs

    • 42% of all pregnancies in are unplanned, 26% end in abortion.

    • An estimated 201 million couples want to limit the number and determine the spacing of their children, but lack access to family planning services.

      • Meeting such needs would, annually

        • Prevent 52 million unwanted pregnancies

        • 22 million induced abortions

        • 1.4 million infant deaths

        • 142 000 pregnancy-related deaths

  • Analysts call for an expansion of FP programs to include: teenagers, sexually active unmarried women, and men


Empowering women can slow population growth

Empowering Women Can Slow Population Growth

  • Studies show that women tend to have fewer children if they are

    • Educated

    • Hold a paying job outside the home

    • Live in societies where their human rights are not suppressed.

  • In areas of Africa, Latin America, and Asia, women do

    • almost all domestic work and child care for little or no pay

    • 60-80% of work associated with growing food, and gathering wood and animal dung for use as fuel and for hauling water (Fig. 6-13).

    • “For poor women the only holiday is when you are asleep”

  • Sons more valued than daughters

    • “Many women in the developing world are trapped in poverty by illiteracy, poor health, and unwanted fertility. All these contribute to environmental degradation and tighten the grip of poverty.”


The human population and its impact chapter 6 miller and spoolman 2010

Figure 6.13Women from a village in the West African country of Burkina Faso returning with fuelwood. Typically they spend 2 hours a day two or three times a week searching for and hauling fuelwood.


Case study slowing population growth in china the one child policy 1

Case Study: Slowing Population Growth in China: the One-Child Policy (1)

  • Has made impressive effort to feed its people and control its population

    • In 1960s, established most extensive, intrusive and strict population control.

      • Only alternative to mass starvation

    • Crude birth rate cut in half and TFR dropped from 5.7 to 1.6

    • Despite effort, population will peak about 1.46 billion by 2033

  • Policies that encourage fewer children

    • Discourages premarital sex

    • Urges delay of marriage and limit families to one child

    • Married couples who pledge to have no more than one child

      • More food, larger pensions, free school tuition and preferential employment opportunities for their child.

    • Provides couples with free sterilization, contraceptives and abortion

  • Gender imbalance


Case study slowing population growth in china the one child policy 2

Case Study: Slowing Population Growth in China: the One-Child Policy (2)

  • World’s fastest growing economy

    • But an aging population

    • Has environmental problems that could ultimately limit economic growth

      • 19% if world’s population, but only 7% of world’s freshwater and cropland, 4% of its forests, and 2% of its oil.

      • Only 15% of its land protected on paper

    • Only 29% of population has access to adequate sanitation

    • In 2005, China’s deputy minister said:

      • “Our raw materials are scarce, we don’t’ have enough land, and our population is constantly growing. Half of our water in our seven largest rivers is completely useless. One-third of the urban population is breathing polluted air.”

    • As more people move into the middle-class, per capita consumption increases


Case study slowing population growth in india 1

Case Study: Slowing Population Growth in India (1)

  • Five decades of attempting to control population has had only modest success.

    • In 1952, pop size was 400 million; 2008, 1.1 billion.

    • In 2015, will be most populous country, by 2050, projections estimate 1.76 billion.

    • Even though Indian government provides information on the advantages of small families and made family planning available throughout the country

      • TFR currently at 2.8

      • 90% of couple are aware of at least one method of birth control, only 48% use one.

    • Population control: gender bias


Case study slowing population growth in india 2

Case Study: Slowing Population Growth in India (2)

  • Poverty

    • 82% of rural population lack adequate sanitation

    • 80% of its people struggling to live on less than $2/day

    • Malnutrition suffered by 40% of population and 50% of children

  • Environmental problems

    • 17% of world’s people, only 2.3% of world’s land resources and 2% forests

    • Half cropland degraded from erosion and overgrazing

    • 2/3 of water seriously polluted

    • Many cities suffer from serious pollution.

    • Huge and growing middle class increasing per capita ecological footprint


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