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

Chapter 5The Human Population

Copyright © 2008 Pearson Prentice Hall, Inc.

EnvironmentalScienceTenth Edition

Richard T. Wright

Human Population Growth and the Consequences

Human population expansion and its causeDifferent worldsConsequences of population growth and affluenceDynamics 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 http://math.berkeley.edu/~galen/popclk.html

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

% S

urvi

val

AgeBirth Death

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.2.02 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 recyclingI = P x A x T

S

Population Increase in Developed and Developing Countries

Population Data for Selected Countries (Table 5-2)

Country Total Fertility Rate

Doubling Times (Years)

World 2.7 58

Developing Countries

2.9 47

Developed Countries

1.6 700

United States 2.0 117

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 rates2. High consumptive

lifestyles: use 80% of world’s wealth

3. Intense poverty4. Eat high on the food

chain5. Long doubling times6. High environmental

degradation7. Twenty percent of the

world’s population

1. Developing2. Developed3. Developing4. Developed5. Developed6. Developed7. 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 PopulationCauses

MORE

LESS

deforestationresource depletionloss of agricultural landbiodiversitydiseasepest resistancepopulation migrationirrigationwetlands

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 United States

Population Profile United States

Population Profile of Italy

Population Profile Italy

Population Projections United States

Increased fertility rateof 2.0 and current migration

Fertility rate of 1.8

Population Profile Developing Country

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 50-60 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 2000

65 out of 117 countries will not be able to feed their own peopleOne billion people will be living in cities that cannot support their inhabitants400 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