ChapterChapter 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

• Current world Population

• Current US population

Human Population Growth and the Consequences

• Human population expansion and its cause• Different worlds• Consequences of population growth and

affluence• Dynamics of population growth

• Students will be able to discuss and show mastery on the above topics

Human Population Expansion and Its Cause

• Reasons for the patterns of growth– Biotic potential exceeds environmental

resistance: birth rates exceed death rates

• There are 7 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







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

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

Average Number of Children, Grandchildren, and Great Grandchildren

• America

• West Germany

• Africa

– 14

– 5

– 258

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 = $50,666

• Middle-income, moderately developed countries– Latin America, South Africa, China– Average GNI per capita = $6,000

Economic Categories Based on Per Capita Gross National Income (see Fig. 5-4)

• Low-income, developing countries– Western and central Africa, India, central Asia– Average GNI per capita = $454

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!

Tragedy of the commons

• http://www.youtube.com/watch?v=ptLQSzdNNd8

• http://www.youtube.com/watch?v=B6RyBHG51VQ

Dimensions of the Human Poverty Index

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


• 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.


• How does stewardship (S) affect the IPAT formula?– S = wildlife conservation, pollution control,

energy conservation, and recycling

I = P x A x TS

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


• 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

Consequences of Population Growth and Affluence

• The developing countries

• Affluence

Developing or Developed Nations?

• High fertility rates

• High consumptive lifestyles: use 80% of world’s wealth

• Intense poverty

• Eat high on the food chain

Developing or Developed Nations?

• Long doubling times

• High environmental degradation

• Twenty percent of the world’s population

Basic Human Needs

• Drinkable water

• Edible food

• Safe housing

• Health care

• An education

• A job

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

• http://www.youtube.com/watch?v=c6pcRR5Uy6w

• rule of 70

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

Phases of Demographic Transition

• Phase I: primitive stability (CBR = CDR)

• Phase II: declining CDR, CBR remains high accelerating population growth

• Phase III: declining fertility rate, but significant population growth continues

• Phase IV: modern stability with low CBR and CDR

Demographic Transition Comparisons (Figure 5-17)

• Phase IV: developed countries

• Phases II and III: developing countries

In the Year 2000

• 65 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

In 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• nature's way.wmv

The World in Balance

• http://www.youtube.com/watch?v=6ANMPYYkkF0

End of Chapter 5

PPT by Clark E. Adams

Documents

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