Chapter 7 The Human Population

1. Chapter 7 The Human Population

2. The Human Population • The Environmental Implications of China’s Growing Population • China has 20% of the world’s population (1.3 billion) • Currently the largest emitter of CO2 • 1970s started the 1 child per family policy • This has now been reversed • Population may start to decline by 2040 • Beginning to improve conditions • Other nations pose a risk

4. 7 Billion & Counting

5. How did we get so big so fast?

6. Earth’s Carrying Capacity • Growing populations of humans provides an increasing supply of intellect that leads to increasing amounts of innovation. • By employing creativity humans can alter Earth’s carrying capacity • Food deficit vs. ongoing improvements!?

7. Scientists Disagree on Earth’s Carrying Capacity Figure 7.1

8. Scientists Disagree on Earth’s Carrying Capacity • The following graphs show theoretical models of food supply and population size.

9. Why Scientists Disagree about the Carrying Capacity? • --Believe outgrown OR will eventually outgrow available supply of resources such as food, water, timber, fuel, etc. • --Malthus= Human population growing exponentially but food supply growing linearly • Environmental Scientists still believe that we will reach our carrying capacity= human population growth will decline • --Do not believe there is a carrying capacity for humans • --Growing population provides an increasing supply of intellect that leads to increasing amounts of innovation • Inventions/technological advances increase carrying capacity over time • --Ex: Development of arrow made hunting more efficient

10. Population Growth Until the Middle Ages, human populations were held in check by diseases, famines and wars, and thus grew very slowly. It took all of human history until 1800 to reach 1 billion. 150 years to reach 3 billion 12 years to go from 5 to 6 billion Human population tripled during the twentieth century. “Natural Population Control” = Disease, Famine, War

11. Factors that Drive Human Population Growth • Demography- the study of human populations and population trends. • Changes in Population Size • Migration (emigration & immigration) • Fertility • Life Expectancy • Age Structure

13. Changes in Population Size • Immigration- the movement of people into a country • Emigration- the movement of people out of a country. • Net migration rate- the difference between immigration and emigration in a give year per 1,000 people in the country.

14. How do Populations change in size • Global Scale: Birth rate – death rate = growth rate • b - d = r growth rate (r) can be + or – • Local Scale: movement from one region to another • Immigration – # individuals entering a population • Emigration - # individuals leaving a population • r = (b – d) + (i – e)

15. Family Planning • Regulation of the number or the spacing of offspring through the use of birth control. • The more education, the less children people tend to have.

16. Ideal Family Size Is Culturally And Economically Dependent Many factors increase our desire for children Labor Old Age Support Status Love Other factors discourage reproduction Cost (Monetary, Lifestyle) Negative Status Could we have a birth shortage?

18. Birth Reduction Pressures • In developing countries, higher income often means families can afford more children, thus fertility often increases. • In less-developed countries, adding another child to a family usually does not cost much, while in developed countries, raising an additional child can carry significant costs.

19. 10 Factors affecting Birth rate and Fertility rate • Average level of education and affluence • Importance of children as a part of the labor force • Urban areas (with access to family planning) • Cost of raising and educating children • Education and employment opportunity for women • Infant mortality rate • Average age of marriage and 1st child • Availability of pension system • Availability of legal abortions • Birth control/religion

21. Life Expectancy • Life expectancy- the average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average life span and death rate of that country.

22. Life Expectancy • Infant mortality rate- the number of deaths of children under 1 year of age per 1,000 live births. • Child mortality rate- the number of deaths of children under age 5 per 1,000 live births.

23. Predictor of health care, food supply, drinking water, sanitation, and prenatal care. • US: 6.6 • France and Sweden: 2.5, 3.6 • Liberia: 99 • Bolivia: 50 • Varies within each country as well.

24. Life Span and Life Expectancy • Declining mortality is the primary cause of most population growth in last 300 years. • Worldwide, average has risen from 40 to 65.5 over the past century. • Greatest progress has been in developing countries. • Largely due to curbing infant mortality

25. Life Expectancy-1930

26. Life Expectancy-1960

27. Life Expectancy-1990

28. Comparison

29. Aging and Disease • Second largest killer to heart disease. • Tuberculosis and malaria were responsible for the most amount of deaths. • HIV has taken its place.

30. AIDS and HIV • Responsible for the for the greatest amount of human deaths. • Affects humans in their reproductive years. • Most prominent in Africa.

32. Demographic Implications of Living Longer • A population growing rapidly due to natural increase has more young people than a stationary population. • Both rapidly and slowly growing countries can have a problem with dependency ratio. • The number of non-working compared to working individuals in a population.

33. Age Structure • Age structure diagrams (population pyramids)- visual representations of age structure within a country for males and females.

34. Age Structure • Four general types: • Pyramid- population w/ many young and high death rate (short average lifetime) • Inverted pyramid- top heavy (Japan?) • Column- birth rate and death rate are low and a high % of pop is elderly • Column w/ a bulge- event in the past caused a high birth or death rate for some age group

35. Age Structure Diagrams Positive Growth Slow Growth Negative Growth/ Zero Growth Pyramid Shape Vertical Edges Inverted Pyramid

37. Age Structure

40. Age Structure Lab

41. The Demographic Transition • The theory of the demographic transition is the theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth. **Write in your notes sheet under: What is it?**

43. Theory of Demographic Transition • Phase1 – Pre-Industrial – Before the industrial Revolution • Phase 2 – Transitional - India • Phase 3 – Industrial – US & Canada • Phase 4 – Post Industrial – UK, Germany, Russia, Italy, Japan

44. The Stages of the Demographic Transition • Phase 1: Slow population growth because there are high birth rates and high death rates which offset each other. • Phase 2: Rapid population growth because birth rates remain high but death rates decline due to better sanitation, clean drinking water, increased access to food and goods, and access to health care. • Phase 3: Stable population growth as the economy and educational system improves and people have fewer children. • Phase 4: Declining population growth because the relatively high level of affluence and economic develop encourage women to delay having children.

45. Population Size & Consumption Interact to Influence the Environment • Population size: critical factor in the impact of humans on Earth • Amount of resources each person uses is another critical factor • Every human exacts a toll on the environment by eating, drinking, generating waste, and consuming products • Population and economic development are not equally distributed around the world, THUS the human impact on natural resources is also unequally distributed

46. Developed vs. Developing • Developed countries- countries with relatively high levels of industrialization and income. • Developing countries- countries with relatively low levels of industrialization and income of less that $3 per person per day.

47. The relationship between economic development and population growth rate for developing nations. • Population disparity between rich and poor countries has accelerated in recent decades • Shows the relationship b/t economic development & population growth rate for developing nations • Developing Nations: grow rapidly • Developed Nations: Growth has almost leveled off **Impoverished countries are increasing their pop. more rapidly than affluent countries

48. The 12 Most Populous Countries in the World • About 5.6 billion live in developing countries • Only about 1.3 billion live in developed countries • 9 out of 12 most populous nations on Earth are developing countries

49. Developing v. Developed Countries and Resources • Although only 1/5 of the human pop. live in developed countries, those people consume more than ½ of the world’s energy and resources • One person in a developed country may have 2 to 10 times the environmental impact of a person in a developing country

50. Ecological Footprints • Provides a way to measure the effect of affluence on the planet • A measure of human demand on the Earth’s ecosystems