Understanding Human Population Growth and its Effects: A Comprehensive Lecture

2. This lecture will help you understand: • Human population growth • Different viewpoints on this growth • Population, affluence, and technology’s effects • Demography • Demographic transition • Factors affecting population growth • The HIV/AIDS epidemic • Population and sustainable development

4. Central Case Study: China’s One-Child Policy • In 1970, China’s 790 million people were exhausting their resources and faced starvation if growth continued • The government instituted a one-child policy • The growth rate plummeted • The policy is now less strict • The successful program has had unintended consequences • Killing of female infants and an imbalance in male to female ratios • Increasing number of elderly and fewer young people in the workforce

6. The human population is growing rapidly • Our population grows by over 70 million each year • We added the most recent billion in 12 years • Growth rates vary from country to country • The current world growth rate is _____% • At this rate, the human population of the planet would double/triple/quadruplein 58.3 years

9. Is population growth a problem? • Better technology, sanitation, medication, and increased food supply have increased growth • Death rates drop, but not birth rates • Infant mortality rate? • Population growth was seen as good • Support for elderly, a larger labor pool • _______________ wrote An Essay on the Principles of Population (1798) • Humans will outstrip food supplies • War, disease, starvation reduce populations

11. Is population growth a problem? • Neo-Malthusians believed? • Who wrote a book that supported these beliefs? • Intensified food production fed more people • Who believed we would find new resources? • Environmental scientists argue that there are finite resources • Land is limited, extinct species are gone forever

13. Some national governments now fear falling populations • Policymakers believe population growth increases economic, political, and military strength • But growth is correlated with ________________ • Strong, rich nations have__________growthrates • Weak, poor nations have __________growth rates • Some nations offer incentives for more children • Elderly need social services • 66% of European governments think their birth rate is too low • 49% of non-European nations feel their birth rates are too high

14. Population is one of several factors that affect the environment • The IPAT model: what is the equation and what does each variable stand for? • Further model refinements include the effects of education, laws, and ethics on the formula

15. Population is one of several factors that affect the environment • Impact equates to pollution or resource consumption • Humans use ___% of Earth’s net primary production • Technology has increased/decreased efficiency and reduced our strain on resources, resulting in further population growth • Give an example • What has Modern China’s increasing affluence is caused? Give two effects.

16. Demography • Demography = the application of population ecology to the study of change in human populations • All population principles apply to humans • Environmental factors limit population growth • There is a carrying capacity for all species, including humans • Humans raise the environment’s carrying capacity through technology • How many humans can the world sustain? • 1 billion to 33 billion: prosperity to abject poverty • Population growth can’t continue forever

17. Demography is the study of human population • Demographers study: • Population size • Density and distribution • Age structure • Sex ratio • Birth, death, immigration, and emigration rates • Population size • Current world population is just over 7 billion • Estimated to grow to over 9 billion by 2015

19. Population density and distribution • Populations on Earth are distributed equally/unequally? What kind of distribution is this? • Highest density areas contain what kind of biomes? • _______ are local high-density areas • Lowest density areas are found where? • ___________density impacts the environment

21. Age structure • Age structure describes the relative numbers in each age class within a population • Age structure diagrams (population pyramids) show age structure • Wide base denotes __________ • Low/highreproduction, slow/rapid population growth • _____________distribution: remains stable as births keep pace with deaths • _________base denotesmore/fewer young than old • Population will likely increase/decrease over time

23. Age structure • China’s age structure is changing • In 1970, the median age was 20; by 2050 it will be 45 • By 2050, over 300 million will be over 65 • Fewer people will be working to support social programs to assist the elderly

25. Sex ratios • Unequal sex ratios can impact population growth • Human sex ratios at birth slightly favor males • For every 100 females born, 106 males are born • In China, 120 boys were reported for 100 girls • Culture values males over females • The government’s one-child policy • Females have been selectively aborted • The undesirable social consequences? • Many single Chinese men • Increased risk of HIV • Teenage girls are kidnapped and sold as brides

26. Population change results from birth, death, immigration, and emigration • Whether a population grows, shrinks, or remains stable depends on rates of birth, death, and migration • ________and_________addindividuals • ________and_________removeindividuals • Technological advances caused increased/decreased deaths • The increased/decreasedgap between birth and death rates resulted in population expansion

27. Population change results from birth, death, immigration, and emigration • Immigration/emigration have become more important • This movement causes environmental problems • No incentives to conserve resources • Overall global growth rate has declined in recent years

29. Total fertility rate influences population growth • Total fertility rate (TFR)? • Replacement fertility? • TFR has been decreasing/increasing in many nations due to: • What three major movements or historical events? • In Europe as a whole, TFR is now 1.6 • Natural rate of population change?

31. Many nations are experiencing the demographic transition • In countries with good sanitation, health care, and food, people live longer • Life expectancy? • Has increased with reduced rates of infant mortality • Demographic transition? • What does this explain? • How many stages does the population undergo?

32. Many nations are experiencing the demographic transition • Pre-industrial stage? • High/low birth rate to compensate for high infant mortality • Population growth is slow/fast • Transitional stage? • Birth rates remain high/lowsince people are not used to the low infant mortality/natalityrates • Population grows quickly/slowly

33. Many nations are experiencing the demographic transition • Industrial stage? • Difference between birth and death rates increases/decreases • Population growth slows/grows • Post-industrial stage? • Population stabilizes or even shrinks

35. Is the demographic transition a universal process? • It has occurred in Europe, the U.S., Canada, Japan, and other nations over the past 200–300 years • But it may or may not apply to developing nations • The transition could fail in cultures that: • Place greater value on childbirth • Grant women fewer freedoms For people to attain the material standard of living of North Americans, we would need the natural resources of four and a half more Earths

36. Population and Society • Many factors affect fertility in a given society: • Access to family planning • Rates of infant mortality • Levels of women’s rights • Level of affluence • Importance of child labor • Government support for retirees

37. Family planning is a key approach for controlling growth • Family planning? • Birth control? • Contraception? • Rates range from less than 10% (14 countries in Africa) to 84% (China)

38. Family planning is a key approach for controlling growth • Low use of family planning may have different causes • Rural areas may have limited availability • Religious doctrines or cultural influences may reject family planning • Family planning gives women control over their reproductive window? • Potential to produce 25 children during the window • Family planning may delay first reproduction, space births, or “close” the window when desired family size is achieved

40. Family-planning programs are working around the world • Funding and policies that encourage family planning lower population growth rates in all nations, regardless of level of industrialization • Thailand’s educational-based approach to family planning reduced its growth rate from 2.3% to 0.5% • Brazil, Mexico, Iran, Cuba, and other developing countries have active programs • These entail setting targets and providing incentives, education, contraception, and reproductive health care

42. Empowering women reduces fertility rates • Where women have the ability to decide whether and when to have children, fertility rates fall, and children are better cared for, healthier, and better educated. • Fertility rates drop most noticeably when women gain access to contraceptives and family-planning programs • As women receive educational opportunities, fertility rates decline • Two-thirds of the world’s illiterate are women • Education leads to delayed childbirth as women pursue careers

44. Increasing affluence lowers fertility • Poorer societies have higher population growth rates • Why? • What can more affluent societies provide to the women?

46. Increasing affluence lowers fertility • Poverty exacerbates population growth; population growth exacerbates poverty • Population growth in poor nations increases/decreases environmental degradation • Farming degrades soil in arid areas (Africa, China) • Poor people cut forests, deplete biodiversity, and hunt endangered species (e.g., great apes)

48. Expanding wealth can increase the environmental impact per person • Affluent societies have more/less resource consumption and waste production • People use resources from other areas, as well as from their own • Ecological footprints are small/large • People in affluent societies have smaller/larger ecological footprints • Not only is the world population increasing, but the consumption per person is also rising

49. Expanding wealth can increase the environmental impact per person • Biocapacity? • What is the equation for Ecological deficit? • What is the equation for Ecological reserve? • We are running a global ecological deficit • Humanity’s global ecological footprint exceeds biocapacity by _____% • The richest____% of the world’s population uses ____% of the world’s resources