Chapter 5 The Human Population Copyright © 2008 Pearson Prentice Hall, Inc. Environmental Science Tenth Edition Richard T. Wright

Human Population Growth and the Consequences Human population expansion and its cause Different worlds Consequences of population growth and affluence Dynamics of population growth

Human Population Expansion and Its Cause Reasons for the patterns of growth Biotic potential exceeds environmental resistance: birth rates exceed death rates There are 6.6 billion people on Earth If each one stood up, pronounced their name and sat down It would take 600 years to complete roll call By 2025 it will take 1,000 years to complete this exercise

World Population Over the Centuries 9,000 human beings added to the planet every hour

Modeling Population Growth Human Population Growth and Regulation

Modeling Population Growth Human Population Growth and Regulation

Modeling Population Growth Human Population Growth and Regulation

Modeling Population Growth Human Population Growth and Regulation

Modeling Population Growth Human Population Growth and Regulation

Reasons for the Human Population Explosion Causes of disease recognized Improvements in nutrition Discovery of antibiotics Improvements in medicine Increase in number of women who actually reach child-bearing age Short doubling times in some countries

Changing Human Survivorship Curves: Went from B to A % Survival Age BirthDeath A B

World Population Growth and Absolute Growth

Key terms Infant mortality rate Overall health Life Expectancy Quality of life

Population Projections Based on Different Fertility Assumptions Maintain fertility rate of 2.6 children/woman Gradual decline in fertility in developing countries children/woman ½ child lower than medium projection ½ child higher than medium projection

Different Worlds Rich nations, poor nations Population growth in rich and poor nations Different populations, different problems

Major Economic Divisions of the World Gross national income/capita

Economic Categories Based on Per Capita Gross National Income (see Fig. 5-4) High-income, highly developed, industrialized countries United States, Japan, Canada Average GNI per capita = $26,710 Middle-income, moderately developed countries Latin America, South Africa, China Average GNI per capita = $1,850 Low-income, developing countries Western and central Africa, India, central Asia Average GNI per capita = $430

Disparities Developed countries 15% of the world’s population Control 80% of the world’s wealth Low-income developing countries 37% of the world’s population Control 3.0% of the world’s gross national income Difference in per capita income: 63 to 1!

Different Populations, Different Problems IPAT Formula: calculates human pressure on the environment (I = P x A x T) I = environmental impact P = population A = affluence and consumptive patterns T = level of technology in the society

Different Populations, Different Problems Environmental impact of developing countries due to “P.” Environmental impact of developed countries due to “A” and “T.” Both have some measure of “I” for different reasons. Average American places at least 20 times the demand on Earth’s resources compared to a person in Bangladesh.

Different Populations, Different Problems How does stewardship (S) affect the IPAT formula? S = wildlife conservation, pollution control, energy conservation, and recycling I = P x A x T S

Population Increase in Developed and Developing Countries

Population Data for Selected Countries (Table 5-2) CountryTotal Fertility Rate Doubling Times (Years) World2.758 Developing Countries Developed Countries United States2.0117

Different Populations, Different Problems Human pressure on the environment caused by three factors Population size Affluence Technology

Global Conditions for a Sustainable Population Lower fertility rates (stabilize population) Consumption must decrease Protect the environment (stewardly action must increase

Developing or Developed Nations? 1. High fertility rates 2. High consumptive lifestyles: use 80% of world’s wealth 3. Intense poverty 4. Eat high on the food chain 5. Long doubling times 6. High environmental degradation 7. Twenty percent of the world’s population 1. Developing 2. Developed 3. Developing 4. Developed 5. Developed 6. Developed 7. Developed

Basic Human Needs Drinkable water Edible food Safe housing Health care Education

The Developing Countries Reform the system of land ownership Intensify cultivation of existing land to increase production per unit area Open new land to farm Move to cities and seek employment Engage in illicit activities for income Move to other countries How do these “solutions” aggravate the problems?

Growing Cities

Consequences of Exploding Populations in the Developing World

Consequences of Exploding Populations More Population Causes MORE LESS deforestation resource depletion loss of agricultural land biodiversity disease pest resistance population migration irrigation wetlands

Affluence in the United States Consume the largest share of 11 or 20 major commodities Eat more than three times the global average in meat Lead the world in paper consumption Environment improves with increasing affluence

Affluence in the United States Enables wealthy to clean up immediate environment by transferring waste to more distant locations Affluent isolate themselves and unaware of the environmental stresses caused by their consumptive lifestyles

Dynamics of Population Growth Population profiles Future populations Population momentum The demographic transition

Population Profile United States

Population Profile of Italy

Population Profile Italy

Population Projections United States Increased fertility rate of 2.0 and current migration Fertility rate of 1.8

Population Profile Developing Country

Population Momentum Effect of current age structures on future population growth Determined by percent of population in younger versus older age cohorts

Population Momentum It will take countries with a large base of younger population a long time to achieve stability. Countries like Iraq will continue to grow for years even after the total fertility rate is reduced to replacement level.

Calculating Fertility Rates and Doubling Times (CBR - CDR)/10 = Rate of Increase or decrease in population per 1000 per year 70/ Rate of Increase = Doubling Time

By the Year out of 117 countries will not be able to feed their own people One billion people will be living in cities that cannot support their inhabitants 400 million more women will be in need of child spacing services

By the Year 2000 (continued) 600 million new jobs will need to be created for new entrants into the workforce We will need twice as much fresh water 300 million additional children will need teachers, books, and classrooms