1. Chapter 7 The Human Population

2. 1. Scientists Disagree on Earth ’ s Carrying Capacity Every 5 days, the human population grows by 1 million people – 1.8 million births and 800,000 deaths.

3. Scientists Disagree on Earth ’ s Carrying Capacity The following graphs show theoretical models of food supply and population size. Top: There will be a “food deficit” when the population gets too big. Bottom: Innovation will increase the amount of available food.

4. 2. Factors that Drive Human Population Growth Demography - the study of human populations and population trends Changes in Population Size Fertility Life Expectancy Age Structure Migration

5. 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

6. Changes in Population Size Crude birth rate (CBR) = the number of births per 1,000 individuals per year Crude death rate (CDR) = the number of deaths per 1,000 individuals per year Global population growth rate = (CBR- CDR) / 10 National population growth rate = [(CBR+ immigration) - (CDR + emigration)] / 10 Doubling time (in years) = 70/growth rate “Rule of 70”

7. Changes in Population Size Example Worldwide in 2009, there were 20 births and 8 deaths for every 1,000 people. Global pop rate = [CBR – CDR] / 10 = [20 - 8] / 10 = 1.2% (The global population grew by 1.2%; adding 1 million people everyday.) *We use 10 because it comes out as a percentage (the same as if we divided 1000 by 100)

8. Changes in Population Size Example For a country with 50 births and 40 deaths for every 1,000 people, with 0 immigration and 6 emigration. National pop rate = [(CBR + immigration) – (CDR + emigration)] / 10 = [(50 + 0) – (40 + 6)] / 10 = 0.4%

9. Changes in Population Size Example Doubling time = time it takes a pop to double. Use the “Rule of 70.” 1. What is the doubling time for a country growing at 3% per year? Doubling time = 70/growth rate = 70/3 = 23.3 yrs 2. What is the growth rate of a country with a doubling time of 10 years? Growth rate = 70/doubling time = 70/10 = 7%

10. Fertility Total fertility rate - an estimate of the average number of children that each woman in a population will bear Replacement level fertility - the total fertility rate required to offset the average number of deaths in a population and for the current population size to remain stable

11. Fertility 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

12. 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

13. 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

14. Aging and Disease Even with high life expectancy and low infant mortality, you can still have a high crude death rate because a population might have a lot of older individuals. Infectious disease is the 2 nd biggest killer worldwide after heart disease (i.e. HIV-related deaths, tuberculosis, malaria)

15. Age Structure Age structure diagrams - visual representations of age structure within a country for males and females

16. Migration Regardless of its birth and death rates, a country may experience population growth, stability, or decline as a result of migration. + migration rate: more immigrants coming in than going out - migration rate: more people going out than coming in

17. Migration New Zealand has a population of 4.3 million people, a TFR of 2.1, and a net migration rate of 2 per 1,000. How many people will New Zealand gain next year as a result of immigration? If everything stays the same, when will the population double? 2 = x x = 8,600 people/year 1,000 4,300,000

18. Migration If everything stays the same, when will the population double? Net migration = (# of immigrants)/(# of people in pop) 8,600 people/year = 0.2% per year 4,300,000 people Doubling time = 70 / rate 70 / 0.2 = 350 years

19. 3. Many nations go through a demographic transition Theory of the demographic transition - the theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth

20. 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.

21. Family Planning Family planning - the regulation of the number or spacing of offspring through the use of birth control.

22. 4. Population size and consumption interact to influence the environment The 12 Most Populous Countries in the World

23. The relationship between economic development and population growth rate for developing nations.

24. Ecological Footprints Affluence - having a lot of wealth such as money, goods, or property

25. The IPAT Equation To estimate the impact of human lifestyles on Earth we can use the IPAT equation: I mpact= P opulation X A ffluence X T echnology

26. Local, Global, Urban Impacts Local: cutting trees for agriculture, soil degradation, water pollution Global: consumption of fossil fuels (including importing) and food, increase in greenhouse gases released Urban: 75% of people in developed countries live in urban areas. More solid waste, pollution, CO 2 emissions. Includes slums, shantytowns, etc. with little access to sanitation, clean water, more diseases.

29. The Impact of Affluence Gross domestic product (GDP) - the value of all products and services produced in a year in that country GDP is made up of consumer spending, investments, government spending, and exports minus imports. A countries GDP often correlates with its pollution levels. Rising income generally correlates with falling birth rates and reducing population size should lead to a reduction in environmental impact