Environmental Science PowerPoint Lecture

1. Environmental Science PowerPoint Lecture Principles of Environmental Science - Inquiry and Applications, 1st Edition by William Cunningham and Mary Ann Cunningham

2. Chapter 4 - Topics • Population growth • Limits to growth: some opposing views • Human demography • Population growth: opposing factors • Demographic transition • Family planning and fertility control • The future of human populations

3. Part 1: Population Growth World population now over 6 billion

4. Current Birth and Death Rates • Every second: 4 or 5 children are born, while 2 other people die • Net gain: 2.5 humans added to the world population every second, 78 million added every year

5. Effect of Birth Rate and Death Rate on Population Size

6. Decisions on how many children to have are influenced by many factors, including culture, religion, politics, need for old-age security, and immediate family finances.

8. Human Population Levels Throughout History

12. Part 2: Limits to Growth Varying Perspectives • Overpopulation causes resource depletion and environmental degradation • Human ingenuity and technology will allow us to overcome any problems - more people may be beneficial • Resources are sufficient to meet everyone’s needs - shortages are the result of greed, waste, and oppression

14. Part 3: Human Demography • Demography - vital statistics about people, such as births and deaths • Two demographic worlds • Less-developed counties represent 80% of the world population, but more than 90% of projected growth • Richer countries tend to have negative growth rates

18. By 2050, India will probably be the world’s most populous country.

19. World Population Density

20. Fertility and Birth Rates • Fecundity - physical ability to reproduce • Fertility - the actual production of offspring • Crude birth rate - number of births per year per thousand people • Total fertility rate - number of children born to an average woman during her reproductive life • Zero population growth (ZPG) - occurs when births + immigration just equal deaths + emigration

21. Regional Declines in Total Fertility Rates

22. China’s one-child- per-family policy decreased the country’s fertility rate from 6 to 1.8 in two decades. However, the policy is very controversial.

24. As incomes rise, so does life expectancy.

25. Living Longer: Demographic Implications • A population growing by natural increase has more young people than does a stationary population. • Dependency ratio - the number of nonworking compared to working individuals - declining in countries such as the U.S. and Japan • If current trends continue, by 2100 the median age in the U.S. will be 60.

26. Changing Age Structure of the World’s Population

29. Part 4: Population Growth -Opposing Factors • Pronatalist pressures - factors that increase people’s desires to have children • Birth reduction pressure - factors that tend to reduce fertility

30. U.S. Birth Rates: 1910-2001

31. Part 5: Demographic Transition • Optimistic view - world population will stabilize during this century • Pessimistic view - poorer countries of the world are caught in a “demographic trap” - helping poor countries will only further threaten the earth’s resources • Social justice view - overpopulation due to a lack of justice, not resources

32. Demographic Transition Accompanying Economic and Social Development

33. Demographic Transition in China

34. Infant Mortality and Women’s Rights

35. Birth Control Methods

36. Part 7: The Future of Human Populations U.N. Projections