Population Ecology: Human Population and Its Impact

1. Population Ecology: Human Population and Its Impact Milton High School AP Environmental Science

2. What is demography and why is it important? The study of the vital statistics that affect population size. - Size - Age Distribution - Density - Dispersion

5. November 8, 2009 World Population United States Population 6,795,788,940 307,889,927 August 25, 2011 World Population United States Population 6,957,846,471 312,067,591

6. Is the world overpopulated? The world’s population is projected to increase from 6.6 billion to 8.9 billion by 2050. The debate over interactions among population growth, economic growth, politics, and moral beliefs is one of the most important and controversial issues in environmental science.

7. Can our Earth support more people? Some argue that the planet has too many people. Some feel that the world can support billions of more people due to technological advances. There is a constant debate over the need to reduce population growth. (Must consider moral, religious, and personal freedom.)

8. Human Population Growth

9. World population growth rate • 1.25% • This adds 80 million • people a year.

10. Population Growth Variables • Crude Birth Rate (CBR) • Crude Death Rate (CDR) • Immigration • Emigration • Density Dependant Factors • Density Independent Factors • Cultural Practices • Technology Revolutions

11. Where are we headed? U.N. world population projection based on women having an average of 2.5 (high), 2.0 (medium), or 1.5 (low) children.

12. Factors Affecting Human Population Size • Births • Deaths • Migration

13. Crude Birth Rate – the number of births per 1,000 people in a population in a given year

14. Crude Death Rate: the total number of deaths per 1000 people. Usually it is measure per country. The crude death rate for the whole world is currently about 9.6 per 1000 per year (based on 62 million deaths in 2006, for a population of 6470 million).

15. Crude Birth Rate Crude Death Rate

16. Total Fertility Rate (TFR) – the average number of children a woman typically has during her reproductive years.

18. Poverty affects population growth • Develop Countries Growth Rate 0.1% • Undeveloped Countries Rate 1.15%

20. How long will it take for the world’s population to double?

21. Rule of 70 – Doubling Time • Life expectancy/growth rate • 70/1.14 = 61 years

22. Indicators of population growth or decline • Natural Increase Rate (NIR) • Percentage by which the population grows in a year. • Total Fertility Rate (TFR) • Average number of children a women will have in her lifetime. • Infant Mortality Rate (IMR) • Average number of infant deaths under 1 year of age, compared with total live births

23. Population Growth Rate CIA World Factbook The average annual percent change in the population, resulting from a surplus (or deficit) of births over deaths and the balance of migrants entering and leaving a country. The rate may be positive or negative. The growth rate is a factor in determining how great a burden would be imposed on a country by the changing needs of its people for infrastructure (e.g., schools, hospitals, housing, roads), resources (e.g., food, water, electricity), and jobs. Rapid population growth can be seen as threatening by neighboring countries. https://www.cia.gov/library/publications/the-world-factbook/fields/2002.html

24. Factors affecting fertility and births • Infant mortality rate • Average age at marriage • Ability of Legal Abortions • Availability of Reliable Birth Control Methods • Religious beliefs, traditions, and cultural norms • Importance of children as part of the labor force • Cost of raising and educating children • Availability of private and public pension systems • Urbanization • Educational and employment opportunities available for women • Importance of young adults joining the military

25. How can family planning help? • Birth Spacing • Birth Control • Health Care for Pregnant Women • Health Care for Infants

26. Key Factors to Fewer Children • Ensuring education • Having jobs outside the home • Living in societies where their rights are not suppressed

27. Two useful indicators of overall health of people in a country or region • Life expectancy • Infant mortality rate

28. Life Expectancy – the average number of years a newborn infant can expect to live

29. Infant Mortality Rate – the number of babies out of every 1,000 born who die before their first birthday

30. Why death rates have declined • Food supplies and distribution • Better nutrition • Medical advances in vaccines and antibiotics • Improved sanitation • Safer water supplies

31. Infant mortality and female literacy

32. Age structure diagrams • Shows the distribution of various age groups in a population. • A great deal of information about the population broken down by age and sex can be read from a population pyramid, and this can shed light on the extent of development and other aspects of the population.

33. Populations with a large proportion of its people in the pre-reproductive ages of 1-14 have a large potential for rapid population growth

34. Teenagers and Pyramids • The number of people under age 15 is the major factor determining a country’s future population growth. • Population pyramids can be used to find the number of economic dependents being supported in a particular population. • 30% (1.9 billion) of people on the planet were under 15 years of age in 2004.

35. Economic Projections • Who will need education • Who will need jobs • Who will determine markets • Who will affect elections • Who will need Medicare

36. How do human populations develop economically?

37. Demographic Transition Model A model used to explain the process of shift from high birth rates and high death rates to low birth rates and low death rates as part of the economic development of a country from a pre-industrial to an industrialized economy.

38. Pre-industrial stage (Stage 1) • High birth and death rates • Low medical care (natural meds) • Population limited by food • availability (internal)

39. Transitional Stage (Stage 2) • Increased food production • Better medical care (esp. antibiotics) • Improved sanitation (esp. drinking water) • Decreased death rate • Birth rate stays high (cultural norms) • Period of rapid growth rate

40. Industrial Stage (Stage 3) • Need for increased labor force • Availability of education (esp. female) • Delay in age of 1st reproduction • Change in cultural norms • Birth rates decline toward zero population growth (ZPG)

41. Post-industrial Stage (Stage 4) • Industrial system no longer supports population • High unemployment, poverty • Food supplies diminish • Environmental health declines (high disease) • Social strife (disease, famine, war) • Increased death rates and decreased birth rates

42. Problems associated with rapid population decline • Can threaten economic growth • Less government revenues with fewer workers • Less entrepreneurship and new business formation • Less likelihood for new technology development • Increasing public deficits to fund higher pension and healthcare

43. China may be rethinking one-child policy • Prompted by growing demographic imbalance • Fear younger generation unable to support ageing population • Alleviate a workforce shortage in the future

44. Altering nature to meet our needs • Reduction of biodiversity • Increasing genetic resistance of pest species • Elimination of many natural predators • Introduction of invasive species • Unsustainable use of renewable resources • Interfering with earth’s biogeochemical cycles • Overuse of fossil fuels