Applying Population Ecology: The Human Population and Its Impact

Applying Population Ecology: The Human Population and Its Impact
Chapter 9 Applying Population Ecology: The Human Population and Its Impact

Core Case Study: Is the World Overpopulated?
The world’s population is projected to increase from 6.6 billion to 8.9 billion between 2006 and 2050. The debate over interactions among population growth, economic growth, politics, and moral beliefs is one of the most important and controversial issues in environmental science.

Much of the world’s population growth occurs in developing countries like China and India. Figure 9-1

Some argue that the planet has too many people. Some feel that the world can support billions of more people due to technological advances. There is a constant debate over the need to reduce population growth. Must consider moral, religious, and personal freedom.

HUMAN POPULATION GROWTH: A BRIEF HISTORY
The human population has grown rapidly because of the expansion of agriculture and industrial production and lower death rates from improvements in hygiene and medicine. In 2006, the population of developed countries grew exponentially at 0.1% per year. Developing countries grew (15 times faster at 1.5% per year.

Where Are We Headed? We do not know how long we can continue increasing the earth’s carrying capacity for humans. There are likely to be between billion people on earth by 2050. 97% of growth in developing countries living in acute poverty. What is the optimum sustainable population of the earth based on the cultural carrying capacity?

Where Are We Headed? U.N. world population projection based on women having an average of 2.5 (high), 2.0 (medium), or 1.5 (low) children. Figure 9-2

Population (billions)
High High 10.6 Medium Low Medium 8.9 Population (billions) Low 7.2 Figure 9.2 Global connections: UN world population projections, assuming that by 2050 women 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—8.9 billion by (Data from United Nations, World Population Prospects: The 2001 Revision, 2002) Year Fig. 9-2, p. 173

Demographic Measures Statistics about people, such as births, deaths, and where they live as well as total population size.

Gross National Product- The most commonly used measure of the economic growth of a country. Value of all goods & services produced. Per capita = per person Density- number of people in a certain space.

Doubling time- The time it takes for the population to double the number of people Rule of 70 Doubling time = Growth Rate

If a population of a country grows at a rate of 5% a year, the number of years required for the pop to double is what?

If a population of a country grows at a rate of 5% a year, the number of years required for the pop to double is what? Rule of 70: Doubling time = = 14 years 5

Immigration- People coming into the population Emigration- The movement of people out of the population. Net Migration- Total number of people moving into or out of the population.

Birth rate (natality)- the number of births in a year per 1,000 people
Birth rate (natality)- the number of births in a year per 1,000 people. Death Rate (mortality)- the number of deaths in a year per 1,000 people

Infant mortality rate- Number of babies out of every 1000 who die before their 1st birthday. If a mother lives in an area with a high infant mortality rate she will tend to have a lot of children to ensure some will make it to adulthood.

FACTORS AFFECTING HUMAN POPULATION SIZE
Population increases because of births and immigration and decreases through deaths and emigration. Instead of using raw numbers, crude birth rates and crude death rates are used (based on total number of births or deaths per 1,000 people in a population).

Growth Rate- includes birth rate, death rate, immigration and emigration Using Raw Numbers: G.R. = (Births – deaths) + (Immigration – Emigration) X Total Population If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the net annual percentage growth rate?

Growth Rate- includes birth rate, death rate, immigration and emigration Using Raw Numbers: G.R. = (Births – deaths) + (Immigration – Emigration) X Total Population If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the net annual percentage growth rate? G.R. = (100 – 40) + (10 – 30) X 100 = ,000

Growth Rate- includes birth rate, death rate, immigration and emigration Using Raw Numbers: G.R. = (Births – deaths) + (Immigration – Emigration) X Total Population If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the net annual percentage growth rate? G.R. = (100 – 40) + (10 – 30) X 100 = (-20) X , ,000

Growth Rate- includes birth rate, death rate, immigration and emigration Using Raw Numbers: G.R. = (Births – deaths) + (Immigration – Emigration) X Total Population If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the net annual percentage growth rate? G.R. = (100 – 40) + (10 – 30) X 100 = (-20) X , , = 40 = 0.4%

Growth rate: Using Crude Rates
Instead of using raw numbers, crude birth rates and crude death rates are used (based on total number of births or deaths per 1,000 people in a population). (Birth rate - death rate) + (immigration rate – emigration rate) X 100 1000

Instead of using raw numbers, crude birth rates and crude death rates are used (based on total number of births or deaths per 1,000 people in a population). (Birth rate - death rate) + (immigration rate – emigration rate) X 100 1000 G.R. = (Birth rate - death rate) + (immigration rate – emigration rate) 10

If the birth rate is 20, the death rate is 30, immigration is 40, and the emigration rate is 10, what is the growth rate for this country?

If the birth rate is 20, the death rate is 30, immigration is 40, and the emigration rate is 10, what is the growth rate for this country? G.R. = (B.R. – D.R.) + (I.R. – E.R.) 10

If the birth rate is 20, the death rate is 30, immigration is 40, and the emigration rate is 10, what is the growth rate for this country? G.R. = (B.R. – D.R.) + (I.R. – E.R.) 10 = (20 – 30) + (40 – 10)

If the birth rate is 20, the death rate is 30, immigration is 40, and the emigration rate is 10, what is the growth rate for this country? G.R. = (B.R. – D.R.) + (I.R. – E.R.) 10 = (20 – 30) + (40 – 10) = = 10 10

If the birth rate is 20, the death rate is 30, immigration is 40, and the emigration rate is 10, what is the growth rate for this country? G.R. = (B.R. – D.R.) + (I.R. – E.R.) 10 = (20 – 30) + (40 – 10) = = 20 = 2%

Average crude birth and death rates for various groupings of countries in 2006. Figure 9-3

Average crude birth rate Average crude death rate
21 World 9 All developed countries 11 10 All developing countries 23 Figure 9.3 Global connections: average crude birth and death rates for various groupings of countries in (Data from Population Reference Bureau) 8 Developing countries (w/o China) 27 9 Fig. 9-3, p. 174

Africa Latin and Central America Asia Oceania United States North
38 15 Latin and Central America 21 6 Asia 20 7 Oceania 17 7 United States 14 Figure 9.3 Global connections: average crude birth and death rates for various groupings of countries in (Data from Population Reference Bureau) 8 North America 14 8 Europe 10 11 Fig. 9-3, p. 174

The world’s 10 most populous countries in 2006 with projections in 2025. Figure 9-4

China 1.3 billion 1.5 billion India 1.1 billion 1.4 billion USA
300 million 349 million Indonesia 225 million 264 million Brazil 187 million 229 million Pakistan 166 million 229 million Bangladesh 147 million 190 million Figure 9.4 Global connections: the world’s 10 most populous countries in 2006, with projections of their population size in In 2006, more people lived in China than in all of Europe, Russia, North America, Japan, and Australia combined. By 2050, India is expected to have a larger population than China. (Data from World Bank and Population Reference Bureau) Russia 142 million 130 million Nigeria 135 million 199 million Japan 128 million 121 million 2006 2025 Fig. 9-4, p. 174

Declining Fertility Rates: Fewer Babies per Women
The average number of children that a woman bears has dropped sharply. This decline is not low enough to stabilize the world’s population in the near future.

Fertility Rates: The Replacement-level Fertility the number of children a couple must bear to replace themselves to stabilize a population is ideally 2.0 children. It is actually slightly higher because some children die. 2.1 in developed countries 2.5 in developing countries because of higher infant mortality

Fertility Rates: Total fertility rate (TFR): the average number of children a woman has during her reproductive years. In 2006, the average global Total Fertility Rate was 2.7 children per woman. 1.6 in developed countries (down from 2.5 in 1950). 3.0 in developing countries (down from 6.5 in 1950).

When Total Fertility Rate = Replacement-level Fertility
Zero population growth

Case Study: Fertility and Birth Rates in the United States
Nearly 2.9 million people were added to the U.S. in 2006: 59% occurred because of births outnumbering deaths. 41% came from illegal and legal immigration.

In 2006, the total fertility rate in the United States was slightly > 2.0 Figure 9-5

Replacement Level Baby boom (1946–64)
Births per woman Replacement Level Baby boom (1946–64) Figure 9.5 Total fertility rates for the United States between 1917 and Use this figure to trace changes in total fertility rates during your lifetime. QUESTION: How many children do you plan to have? (Data from Population Reference Bureau and U.S. Census Bureau) Year Fig. 9-5, p. 175

The baby bust that followed the baby boom was largely due to delayed marriage, contraception, and abortion. Figure 9-6

Births per thousand population Demographic transition
End of World War II Demographic transition Depression Baby boom Baby bust Echo baby boom Figure 9.6 Birth rates in the United States, 1910–2006. 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) Year Fig. 9-6, p. 175

Case Study: U.S. Immigration
Since 1820, the U.S. has admitted almost twice as many immigrants and refugees as all other countries combined. Figure 9-8

Number of legal immigrants (thousands)
1907 1914 New laws restrict Immigration Number of legal immigrants (thousands) Great Depression Figure 9.8 Legal immigration to the United States, 1820–2003. 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) Year Fig. 9-8, p. 178

Factors Affecting Birth Rates and Fertility Rates
The number of children women have is affected by: The cost of raising and educating them. Availability of pensions. Urbanization. Education and employment opportunities. Infant deaths. Marriage age. Availability of contraception and abortion.

Factors Affecting Death Rates
Death rates have declined because of: Increased food supplies, better nutrition. Advances in medicine. Improved sanitation and personal hygiene. Safer water supplies. U.S. infant mortality is higher than it could be (ranked 46th world-wide) due to: Inadequate pre- and post-natal care for poor. Drug addiction. High teenage birth rate.

POPULATION AGE STRUCTURE
The number of people in young, middle, and older age groups determines how fast populations grow or decline. The number of people younger than age 15 is the major factor determining a country’s population growth. Changes in the distribution of a country’s age groups have long-lasting economic and social impacts.

Populations with a large proportion of its people in the preproductive ages 1-14 have a large potential for rapid population growth. Figure 9-9

Expanding Rapidly Expanding Slowly Stable Declining
Male Female Male Female Male Female Male Female Expanding Rapidly Guatemala Nigeria Saudi Arabia Expanding Slowly United States Australia Canada Stable Spain Portugal Greece Declining Germany Bulgaria Italy Figure 9.9 Generalized population age structure diagrams for countries with rapid (1.5–3%), slow (0.3–1.4%), zero (0–0.2%), and negative population growth rates (a declining population). Populations with a large proportion of its people in the prereproductive ages of 1–14 (at left) have a large potential for rapid population growth. QUESTION: Which of these diagrams best represents the country where you live? (Data from Population Reference Bureau) Prereproductive ages 0–14 Reproductive ages 15–44 Postreproductive ages 45–85+ Fig. 9-9, p. 179

Expansive/rapid growth
Birth rate exceeds the death rate. Population is getting larger. Pyramid shaped histogram with wide base.

Stable/Slow Growth (Zero Growth)
Birth rate almost equals death rate. The population is not getting any larger or is growing very slowly. Histogram shape is straighter and more box-like until old age Mainly due to immigration

Declining (negative growth)
When the birth rate is smaller than the death rate. The pyramid bulges near the top or is inverted.

32% of the people in developing countries were under 15 years old in 2006 versus only 17% in developed countries. Figure 9-10

Population (millions)
Developed Countries Male Female Age Figure 9.10 Global connections: population structure by age and sex in developing countries and developed countries, (Data from United Nations Population Division and Population Reference Bureau) Population (millions) Fig. 9-10a, p. 179

Population (millions)
Developed Countries Male Female Age Figure 9.10 Global connections: population structure by age and sex in developing countries and developed countries, (Data from United Nations Population Division and Population Reference Bureau) Population (millions) Fig. 9-10b, p. 179

Today, baby boomers make up nearly half of all adult Americans and dominate the populations demand for goods and services. Figure 9-11

Age Age Age Age Females Males Females Males Females Males Females
Figure 9.11 Tracking the baby-boom generation in the United States. (Data from Population Reference Bureau and U.S. Census Bureau) 1955 1985 2015 2035 Fig. 9-11, p. 180

Death from AIDS and war can disrupt a country’s social and economic structure by removing significant numbers of young adults. → leaving very old and very young

About 14% of the world’s population live in countries with stabilizing or declining populations. Global aging may help promote peace. Fewer young adults available for service Smaller families → parents more reluctant to support military that could wipe out offspring Smaller labor force → competition for workers between industry & military Less taxes → decreasing government funds

A rapid population decline can lead to long-lasting economic and social problems. The cost of an aging population will strain the global economy. Figure 9-12

Some problems with rapid population decline. Figure 9-13

• Can threaten economic growth
• 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 healthcare costs Figure 9.13 Some problems with rapid population decline. QUESTION: Which three of these problems do you believe are the most important? Fig. 9-13, p. 182

SOLUTIONS: INFLUENCING POPULATION SIZE
Demographic Transition: As countries become economically developed, their birth and death rates tend to decline. Preindustrial stage: little population growth due to high infant mortality. Transitional stage: industrialization begins, death rates drops and birth rates remain high. Industrial stage: birth rate drops and approaches death rate. Postindustrial stage: birth rate drops below death rate = population is declining

Generalized model of demographic transition. Some developing countries may have difficulty making the demographic transition. Figure 9-14

Demographic stages in countries- As countries becomes industrialized their birth rates decline.

Pre-industrial Harsh living conditions lead to a high birth rate and high death rate. Thus, little population growth.

Transitional As industrialization begins: food production rises
health care improves. So…Death rates drop BUT birth rates remain high The population grows rapidly KEY: move countries through this phase as quickly as possible

Industrial better access to birth control
Industrialization is wide spread The birth rate drops and eventually approaches the death rate. Population growth slows This is because of: better access to birth control decline in the infant mortality rate increased job opportunities for women the high cost of raising children who don’t enter the work force until after high school or college. Birth rate Death rate

Postindustrial The birth rate declines even further, equaling the death rate and thus reaching zero population growth. Then, the birth rate falls below the death rate and the total population size slowly decreases → negative growth rate. 37 countries have reached this stage. (mainly in W. Europe) To most population experts, the challenge is to help the remaining 88% of the world to get to this stage.

Birth rate and death rate Relative population size
Stage 1 Preindustrial Stage 2 Transitional Stage 3 Industrial Stage 4 Postindustrial High Birth rate Birth rate and death rate (number per 1,00 per year) Relative population size Death rate Figure 9.14 Generalized model of the demographic transition. There is uncertainty over whether this model will apply to some of today’s developing countries. QUESTION: At what stage is the country where you live? Total population Low Low Increasing Very high Decreasing Low Zero Negative Growth rate over time Fig. 9-14, p. 183

Developing vs. Developed
Developing (Transitional, Third World): Higher infant mortality rate because of a shortage in prenatal and pediatric care. Thus, they have more children to ensure some survive. Agricultural societies need children to help in the labor force. Lower per capita income or poorer countries need children to provide an income and sometimes contraceptives are not affordable. Women lack education and job opportunities. Developed (Industrial, First World): Educated and working women tend to delay childbearing. Pension systems support people as they age. Family planning and the ability to control fertility. Higher cost of raising children causes people to have smaller families. Abortion is legal. Infant mortality higher in a country due to, for example, - contaminated drinking water - poor nutrition - poor health care- few or no educational opportunities for women.

Urbanization Urbanization is the movement of people from rural areas into cities Urban areas must import most of its food, water, energy, minerals, & other resources because of large populations Large populations produce and consume enormous quantities of resources that can pollute the air, water & land. Disease can easily spread in urban areas because of the high density population. Environmental pressures of urbanization from population growth are reduced because birth rates in urban areas usually are 3-4x’s lower than in rural areas because cities provide more education and employment opportunities.

Family planning has been a major factor in reducing the number of births and abortions throughout most of the world. Women tend to have fewer children if they are: Educated. Hold a paying job outside the home. Do not have their human right suppressed. Have access to contraceptives.

The best way to slow population growth is a combination of: Elevating the status of women: Education Jobs Human rights Investing in family planning. Reducing poverty.

SLOWING POPULATION GROWTH IN INDIA AND CHINA
For more than five decades, India has tried to control its population growth with only modest success. Since 1970, China has used a government-enforced program to cut its birth rate in half and sharply reduce its fertility rate.

Illiteracy (% of adults) 47% 17% 36% Population under age 15 (%) 20%
Percentage of world population 17% India 20% China 1.1 billion Population 1.3 billion Population (2050) (estimated) 1.4 billion 1.6 billion Illiteracy (% of adults) 47% 17% 36% Population under age 15 (%) 20% 1.6% Population growth rate (%) 0.6% 2.9 children per women (down from 5.3 in 1970) Total fertility rate 1.6 children per women (down from 5.7 in 1972) 58 Infant mortality rate 27 Figure 9.15 Global connection: basic demographic data for India and China in (Data from United Nations and Population Reference Bureau) 62 years Life expectancy 70 years Percentage living below $2 per day 80 47 $3,120 GDP PPP per capita $5,890 Fig. 9-15, p. 186

India’s Failed Family Planning Program
Poor planning. Bureaucratic inefficiency. Low status of women. Extreme poverty. Lack of administrative financial support. Disagreement over the best ways to slow population growth.

China’s Family Planning Program
Currently, China’s TFR is 1.6 children per women. China has moved 300 million people out of poverty. Problems: Strong male preference leads to gender imbalance. Average population age is increasing. Not enough resource to support population.

Some countries, including China, penalize couples who have more than one or two children by:
Raising their taxes Charging other fees Eliminating income tax deductions for a couple’s third child Loss of health-care benefits, food allotments and job options Forced abortions

In China couples who pledge to have no more than one child receive
Extra food Larger pensions Better housing Free medical care Salary bonuses Free school tuition for their one child Preferential treatment in employment when their child enters the job market.

Because of one-child policies and cultural issues, in some countries, there is a strong preference for male children. Girls are aborted at a higher rate than boys Some infant girls are killed Male children receive more education & sometimes are even fed better than female children. Result: Rapidly growing gender imbalance or “bride shortage” → resort to kidnapping brides

Environmental Impact Our big footprints

HUMAN ASPECTS ON NATURAL SYSTEMS
Excluding Antarctica, human activities have affect about 83% of the earths land surface. Figure 9-16

HUMAN ASPECTS ON NATURAL SYSTEMS
We have used technology to alter much of the rest of nature in ways that threaten the survival of many other species and could reduce the quality of life for our own species. Figure 9-17

Natural Capital Degradation
Altering Nature to Meet Our Needs Reduction of biodiversity Increasing use of the earth's net primary productivity Increasing genetic resistance of pest species and disease-causing bacteria Elimination of many natural predators Deliberate or accidental introduction of potentially harmful species into communities Using some renewable resources faster than they can be replenished Interfering with the earth's chemical cycling and energy flow processes Relying mostly on polluting fossil fuels Figure 9.17 Natural capital degradation: major ways humans have altered the rest of nature to meet our growing population, needs, and wants. QUESTIONS: Which three of these items do you believe have been the most harmful? How does your lifestyle contribute directly or indirectly to each of these items? Fig. 9-17, p. 188

Environmental Impact Equation
Population X affluence X technology = Environmental impact

High rates of resource use
Developed Countries High rates of resource use Result in high levels of pollution and environmental degradation per person These are believed to be the key factors determining overall environmental impact. (Cont….)

It is estimated that a US citizen consumes 35 X’s as much as the average citizen of India and 100 X’s as much as the average person in the world’s poorest countries. Thus, poor parents in a developing country would need kids to have the same lifetime environmental impact as 2 typical US kids.

Reasons for World Hunger Issues
Unequal distribution of available food Loss of arable land Increasing population size Increasing poverty in developing countries Increasing meat consumption: Eating higher on the food chain consumes more resources Plant/grain based diets can feed greater number of people (use less land, water, fuel to produce)

Strategies for ensuring adequate nutrition for a growing population:
Increase the number of new food crops from a diversity of plant species Distribute food more equitably Increase land are that is dedicated to grain production rather than meat production Assist developing countries in efficient crop irrigation systems.

Factors that affect birth & fertility rates
Educational & employment opportunities Infant mortality rate Average age at marriage Availability of reliable birth control Importance of kids in labor force Urbanization Cost of raising & educating kids Availability of private & public pensions Religious beliefs, traditions & cultural norms

The best way to slow population growth is a combination of: Elevating the status of women: Education Jobs Human rights Investing in family planning → contraceptives Reducing poverty.

1994 Global Summit on Population & Development
Cairo, Egypt Encouraged action to stabilized the world’s population at 7.8 billion by 2050, instead of the projected billion.

The major goals are to: Provide universal access to family-planning services. Improve the health care of infants, children & pregnant women Encourage development of national population policies Improving the status of women by expanding education & job opportunities

Major goals continued:
Increase access to education for girls Increase men’s involvement in child-rearing responsibility & family planning Take steps to eradicate poverty Reduce & eliminate unsustainable patterns of production & consumption.

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