The Human Population and Its Impact Chapter 6

Core Case Study: Are There Too Many of Us?  Estimated 2.4 billion more people by 2050  Are there too many people already?  Will technological advances overcome environmental resistance that populations face?  Should populations be controlled?

Core Case Study: Are There Too Many of Us? cont.  Will growing populations cause increased environmental stresses? Infectious diseases Biodiversity losses Water shortages Traffic congestion Pollution of the seas Climate change

Are there too many of us?

Exponential Growth – a quantity increases at a fixed percentage per unit of time

Fig. 6-2, p High Medium Low Population (billions) Year UN World Population Projections by 2050

Human Population Growth  10,000 years ago: 5 million  2006: 6.7 billion  12/07/2015: 7.29 billion  By 2050: 7.8 billion to 10.8 billion (97% in developing countries)

Human Population Growth  Factors that account for this population increase: 1.Movement into diverse habitats 2.Modern agriculture methods 3.Control of infectious diseases Sanitation, antibiotics, vaccines

Fig. 6-3, p. 126 China 1.5 billion 1.3 billion India 1.4 billion 1.1 billion USA 357 million 304 million Indonesia 292 million 240 million Pakistan 173 million 229 million Brazil 195 million 229 million Nigeria 148 million 205 million Bangladesh 180 million 147 million Russia 129 million 142 million 2008 Japan 119 million 128 million 2025 The World’s 10 Most Populous Countries in million added each year: –80.8 million/year to developing countries –1.2 million/year to developed countries

The Human Population Can Grow, Decline, or Remain Fairly Stable  Three major factors that influence population size: 1.Births 2.Deaths 3.Migration  Population change = (births + immigration) – (deaths + emigration)

1. BIRTHS  Crude birth rate = number of live births per 1000 people per year

1. BIRTHS  FERTILITY RATE – the number of children born to a woman during her lifetime

1. BIRTHS  FERTILITY RATE – the number of children born to a woman during her lifetime  Fertility Rates – Two Types: 1.RLFR (Replacement-level Fertility Rate) Average number of children couples in a population must bear to replace themselves Developed: 2.1 children Developing: 2.5 children

1. BIRTHS  Fertility Rates – Two Types: 2.TFR (Total Fertility Rate) Average number of children born to women in a population during their reproductive years Globally: 2.6/woman Developed: 1.6/woman Developing: 2.8/woman

2. DEATHS  Crude death rate = number of deaths per 1000 people per year

2. DEATHS  Life Expectancy Average number of years a newborn infant can expect to live Globally: 1955 – 48 years 2008 – 68 years 67 in developing 77 in developed 78 in U.S – 74 years

2. DEATHS  Infant Mortality Rate Number of babies out of every 1000 born who die before first birthday Best indicator of a society’s quality of life 1965: Developed countries – 20 babies Developing countries – 118 babies 2008: Developed countries – 6.3 babies Developing countries - 59 babies

3. MIGRATION  Migration = immigration + emigration (negative number)  Reasons: Economics Religious, ethnic, political issues War Environmental degradation

Population Age Structure  Age Structure: the distribution of males and females among age groups in a population  Age Structure Diagram – 3 categories Prereproductive ages (ages 0-14) Reproductive ages (ages 15-44) Postreproductive ages (ages 45 and older)

Fig. 6-8, p. 131 MaleFemaleMaleFemaleMaleFemaleMaleFemale Guatemala Nigeria Saudi Arabia United States Australia China Japan Italy Greece Germany Bulgaria Russia Prereproductive ages 0–14 Reproductive ages 15–44 Postreproductive ages 45–85+ Generalized Population Age Structure Diagrams Expanding Rapidly Expanding Slowly Stable Declining – 85+

Fig. 6-9a, p. 131 Population Structure by Age and Sex – Developed Countries

Fig. 6-9b, p. 131 Population Structure by Age and Sex – Developing Countries

Populations Made Up Mostly of Young People Can Grow Rapidly, cont.  One of the world’s most important population statistics: Nearly 28% (1.9 billion) of the people on the planet were under 15 years old in 2008.

Population Age Structure  Baby Bust: TFR falls below 1.5 children Can lead to severe economic/social problems Countries facing this include: Stable countries Declining countries

Case Study: The U.S. Population  U. S. population 1900: 76 million 1916: 100 million 1968: 200 million 2007: 300 million 2050: 438 million???

Fig. 6-4, p Baby boom (1946–64) Replacement level Births per woman Year Total Fertility Rate for the US between 1917 and

Case Study: The U.S. Population  U.S. Baby Boom : 79 million added (peaked in 1957) TFR in U.S. in 1957: 3.7 children per woman  TFR has steadily declined since then: 2008: 2.1 children per woman  U.S. population still growing and not leveling off  40% of the growth is due to immigration

 Baby-boomers make up half of the adult Americans  In 2008, 13% of Americans were 65 or older  In 2043, 25% of Americans will be 65 or older Will create a shortage of workers Will strain government budget (health care, social security) Tracking the Baby-Boom Generation in the United States

Using Age-Structure Information to Make Population and Economic Projections Tracking the Baby-Boom Generation in the United States

Demographic Transition  Demographic Transition: Hypothesis of population change based on examination of birth and death rates As countries become industrialized, transition takes place in four distinct phases

Death rate Total population Birth rate Decreasing Stage 2 Transitional IncreasingVery high Fig. 6-12, p. 134 Stepped Art Stage 4 Postindustrial NegativeZero Stage 1 Preindustrial Growth rate over time Birth rate and death rate (number per 1,000 per year) Low Stage 3 Industrial Low Four Stages of the Demographic Transition

Demographic Transition  Demographic Transition stages: 1.Preindustrial - slow growth High birth rate High infant mortality rate High death rate

Demographic Transition  Demographic Transition stages: 1.Preindustrial - slow growth High birth rate High infant mortality rate High death rate 2.Transitional – rapid growth due to improved food production and health

Demographic Transition  Demographic Transition stages: 3. Industrial – growth slows Birth and death rates drop Improved food production, health, and education

Demographic Transition  Demographic Transition stages: 3. Industrial – growth slows Birth and death rates drop Improved food production, health, and education 4. Postindustrial – growth levels off and then declines Birth rates equal, then fall below, death rates