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Human Population and Sustainability

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  1. Human Population and Sustainability • Unit 1 – Chapters 6, 1

  2. Essential Questions • How has the population of humans changed over time? • How are various countries trying to control their populations? • What population issues are facing the United States specifically? • What issues are facing the world with regard to rising world population?

  3. Current World Population Growth • Approximately 7 billion people in the world • 310 Million Americans • Every 5 days, the global human population increases by roughly 1 million people • 1.8 million babies are born • 800,000 people die • This rate of growth is fairly recent

  4. Population Growth • Human population growth was slow until around 200 years ago • This J shape seen on the graph represents exponential growth • 10,000 years ago = 500 million people on the planet • Took until 1927 to add first 2 billion people • 50 years (1974) for next 2 billion • 25 years (1999) for next 2 billion

  5. Exponential Growth • Exponential growth expected to continue • By 2050, the Earth may have 7.8 – 10.8 billion* human inhabitants • The rate of population growth has slowed, but the world’s population is still growing exponentially at a rate of about 1.21 % a year (an average of 227,000 people per day) *demographers make predictions which vary greatly

  6. Population Growth Projections

  7. Exponential Growth Distribution • Growth is distributed unevenly • 2010 • 1 % of growth occurred in (MDCs) more-developed countries (growth rate 0.17 %) • 99% of growth in (LDCs) less-developed countries (growth rate 1.4 %)

  8. MDC vs. LDC Population growth

  9. More Developed Countries • MDC • US, Canada, Japan, Australia, New Zealand, and most of Europe • High average income • 19 % of the worlds population • Use 88% of the worlds resources • Produce 75 % of the worlds pollution and waste

  10. Less Developed Countries • LDC • All other nations. • Divided into two groups: • Moderately developed countries ( China, India, Brazil, Turkey, Thailand, and Mexico • Least developed countries (Congo, Haiti, Nigeria, and Nicaragua)

  11. MDCs vs. LDCs

  12. Thomas Malthus • English Clergyman, Professor, and Economist • In 1798 observed two things • the human population was growing exponentially • the food supply was growing linearly • Formed the following conclusions • The human population would in time exceed the food supply • Mass starvation would occur, causing human population to decrease to a sustainable level • The cycle of population growth followed by mass die-offs would repeat endlessly

  13. Exponential vs. Logistic Growth • Exponential Growth • Occurs when a population has essentially unlimited resources to support its growth. • J shaped curve • Eventually exponential growth is converted to logistic growth • Logistic Growth: • Growth rate decreases as the population becomes larger and faces environmental resistance • S shaped curve • Population stabilizes at or near the carrying capacity

  14. Carrying Capacity • There are limits to population growth – the population cannot grow indefinitely • Carrying capacity: maximum population of a particular species that a given habitat can support over a given period • Cultural carrying capacity: the maximum number of people who could live in reasonable freedom and comfort indefinitely without decreasing the ability of the earth to sustain future generations • Animal populations vs. Human population

  15. Fig. 5-14, p. 115

  16. Fig. 5-15, p. 115

  17. Events of the last 250 years

  18. Population comparison 2010 and 2050 Fig. 6-4, p. 127

  19. Major changes that contribute to increasing populations • Humans developed the ability to inhabit almost all areas of the earth • Development of agriculture (both early and modern practices) produced more food per area farmed • *Death rates dropped sharply due to increased sanitation (indoor plumbing, water purification) and health care (antibiotics, vaccines) * birth rates remained static

  20. Factors driving human population growth • Changes in population size • Immigration • Emigration • Crude birth rate • Crude death rate • Fertility • Total fertility vs. replacement level fertility • Life Expectancy • Infant mortality • Child mortality • Aging and disease

  21. Population Dynamics Changes in Population Size • More births than deaths = growth • More deaths than births = declining population • Equal births and deaths = population stability • Immigration (into) • Emigration (out of) • Crude birth rate • Number of live births per 1,000 people in a population in a given year • Crude death rate • Number of deaths per 1,000 people in a population in a given year

  22. Calculating Population Change • Calculate global population growth rate • Example 1: Worldwide, there were 20 births and 8 deaths per 1,000 people in 2009. Calculate the population growth rate (disregard immigration and emigration – why?) • CBR – CDR/10 • Answer in percent • Calculate growth rate of a nation or specific area • A metropolitan region has a starting population of 20,000. In the course of a year, there are 2,000 births, 500 deaths, 200 emigrants, and 100 immigrants. • (Births + immigration) – (deaths + emigration)/ total pop x 100

  23. Doubling Time/Rule of 70 • The time it takes (usually in years) for the quantity of something growing exponentially to double. • Works best when the population is growing at a constant rate. • Doubling time = 70/annual growth rate • Annual growth rate = 70/doubling time • Example 1: Calculate the time it will take for a population growing at an annual rate of 2% • Example 2: Calculate the annual growth rate if it takes 17.5 years for a population to double.

  24. World Growth Rates

  25. Fertility • Total fertility rate (TFR) • An estimate of the average number of children born to women in a population during their reproductive years • 1955: 2.8 in MDC; 6.2 in LDC • 2010: 1.7 in MDC; 2.7 in LDC • Replacement-level fertility rate • The average number of children that couples in a population must bear to replace themselves • In theory it should equal 2(replace parents) • Depends on prereproductive mortality • 2.1 in MDCs; 2.5 + in LDCs • Does not stop population growth immediately

  26. Total Fertility Rates

  27. Factors affecting birth/fertility rates • Importance of children as part of the labor force • Cost of raising and educating children • Availability of, or lack of, pension systems • Urbanization • Educational and employment opportunities for women • Average age at marriage • Availability of legal abortions • Availability of reliable birth control methods • Religious beliefs, tradition, and cultural norms

  28. Life Expectancy • Average number of years a newborn infant can be expected to live • Associated with levels of resource consumption and environmental impacts • Reported 3 ways: overall population, male, & female • Global life expectancy • in 1955 was 48; in 2010 it was 69; 67 for men & 70 for women • 2010: MDCs = 77, LDCs = 67 • Japan has the longest life expectancy of 83 • US life expectancy • In 2010 was 78; 75 for men & 81 for women • Expected to reach 83 by 2050

  29. Factors Affecting Life Expectancy • Access to food supplies • Quality of available nutrition • Access to medical advances: vaccines & antibiotics • Access to improved sanitation & safer water • Exposure of pollutants/environmental hazards • Exposure to HIV/development of AIDS • Life expectancy gap: • Males: dangerous jobs, wars, greater biological risk • Division of labor b/w men and women becoming more evenly divided in MDCs may decrease the life expectancy gap

  30. Infant Mortality • Infant mortality rate (IMR) • The number of babies out of every 1,000 born who die before their first birthday • One of the best measures of a society’s quality of life because it reflects the general level of nutrition and health care • Globally, IMR are decreasing. In 2009 was 46 Greatest decrease in MDCs then gradient to LDC • High infant mortality indicates undernutrition, malnutrition, and high incidence of infectious disease (contaminated drinking water) • Infant mortality rates affect TFR

  31. Infant Mortality Rates (IMR) • 4 million children die before their 1st birthday • United States • Spends the most $ on health care, yet ranks 54th in IMR • IMR dropped from 165 in 1900 to 6.4 in 2010 • Compare to : Sweden = 2.5; France 3.6 • Level of infant mortality may be related to SES • African American =13.6 • Native American = 8.1 • Caucasian = 5.8 • 3 factors contribute to high IMR in the US • Inadequate health care for poor women during pregnancy • Drug addiction among pregnant women • High birth rate for teenage women (dropped until 2005, now increasing again)

  32. Infant Mortality Rates

  33. United States Population Growth • In 1900 population was 76 million, 2010 population is 310 million • Baby boom (1946 to 1964) 76 million people were added to US population • At the peak of the baby boom the TFR was 3.7 children per woman • Since 1972, TFR remains close to 2.1 • Population is still increasing b/c birth rates are greater than death rates and immigration is greater than emigration

  34. TFR in the US b/w 1917 and 2010

  35. Population Age Structure • Age Structure diagrams or pyramids: • the numbers or percentages of males and females in young, middle, & older age groups in that population • Future population growth can be predicted • Each country has a unique shape, although they can be classified into general broad categories • Individuals are divided into three groups • Prereproductive (ages 0-14; bottom of diagram) • Reproductive (ages 15 – 44; middle of diagram) • Postreproductive (ages 45 and older; top of diagram) • The bars of the diagram represent 5 yr increments • Demonstrate demograpic momentum

  36. Age Structure Diagrams

  37. Effect of AIDS on population structure • 27 million deaths b/w 1981 and 2009 • 2 million deaths per year • Leading cause of death globally for ages 15 - 49 • Kills mostly young adults – which leads to many orphaned children (some of which are infected w/ HIV) and an odd shaped age structure diagram. • Social structure and economy are affected • Decreased life expectancy

  38. Demographic Momentum • The rate of future growth is determined by the # of females in their prereproductive years. • Fast growing populations will have a wide base of prereproductive females. • Slowly growing countries will have only a slightly larger base of prereproductive females and stable countries show equal levels of females in all three division (a slight  in the oldest age groups) • Countries with negative growth will have larger numbers or percentages of women in the postreproductive years

  39. Migration • Countries may experience population growth stability, or decline regardless of birth and death rated due to migration • Immigration vs. emigration • 2009: 190 million people migrated from one country to another (60 million from LDCs to MDCs) • Many MDCs continue to experience population growth due to immigration rather than TFR. • Reasons for migrating: • Jobs, economic improvement, religious persecution, ethnic conflicts, political oppression, war, disease, natural disasters, environmental degradation (soil erosion, food and water shortages)

  40. Current Status of the Worlds Population • 2010: 27% of world’s population was under age 15 (prereproductive) • 1.8 billion (1 in 4) individuals are about to enter their prime reproductive years • 30% of these are located in LDCs and 16% in MDCs

  41. MDC vs. LDC

  42. Population Graying • Fastest growing age group are seniors (65 and older) • Seniors are expected to triple by 2050 (1 of 6) • This is called graying of the population • China: • 16 seniors/100 workers (2010) • 30 seniors/100 workers (2025) • 61 seniors/100 workers (2050) • What type of country will be most affected by graying populations?

  43. American Baby Boom • Added 79 million people to the population between and 1964 • Make up about 36% of adult population in the US (makes them powerful in terms of economic and political power) • As the boomers turn 65 the # of Americans over 65 will increase to 1 in 5

  44. Graying of populations