Chapter 6- Read, Take Notes- Quiz Friday How Many People Can the Earth Support? We do not know how long we can continue increasing the earths carrying capacity for humans without seriously degrading the life-support system for humans and many other species. The single driving mechanism for all the environmental problems we face in the world today may be exponential growth. Key Concepts Humans are subject to natural laws and ecological processes such as limiting factors. Significant differences in developed vs. developing worlds Unlimited use of natural resources is unsustainable There are a number of tools to understand populations project future outcomes There are more people living on Earth today than ever before in human history. Both the number of people and the amount of overall consumption exert an impact on the environment. World Population World Population AD-2030 World Population Hans Roling-Human Population Hans Roling-Human Population 200 years 200 countries 4 minutes Population Trends over 200 yrs Today 7 B What Factors Influence the Size of the Human Population? Population size increases because of births and immigration and decreases through deaths and emigration. The average number of children born to women in a population (total fertility rate) is the key factor that determines population size. Calculating Population Change, = (Births + Immigration) ( Deaths + Emmigration) Population Size Natality Number of individuals added through reproduction Crude Birth Rate - Births per 1000 Total Fertility Rate Average number of children born alive per woman in her lifetime Mortality Number of individuals removed through death Crude Death Rate Deaths per 1000 Demographic Transition Calculating the % increase or decrease of a population (CBR CDR)/10 = Rate of increase or decrease in population per 1,000 per year Number of births or deaths/1000 so countries can be compared. Crude because no consideration of who is old or young Calculating Doubling Times 70/Rate of Increase = Doubling Time The world rate of population increase is 1%. How long would it take to double the population? 70 years Calculating % increase (Fertility Rates) and Doubling Times: Practice Calculate the Rates of increase and doubling times Calculating % increase (Fertility Rates) and Doubling Times: Practice Do the problems.. Difference/10 Since CRUDE based on 1000 (percent based on 100) so divide the difference by 10 End of WWII Demographic Transition Depression Baby Boom.. Echo Baby Boom Age Structure Diagrams Positive Growth Zero Growth Negative Growth (ZPG) Pyramid Shape Vertical Edges Inverted Pyramid Population Profiles of the United States Human Population Growth Continues but It Is Unevenly Distributed Population growth in developing countries is increasing 15 times faster than developed countries By 2050, 97% of growth will be in developing countries Should the optimum sustainable population be based on cultural carrying capacity? Major concers that growing populations cause increased environmental stresses? Infectious diseases Biodiversity losses Water shortages Traffic congestion Pollution of the seas Climate change Population Capacity 3 BBC Water UsePopulation Capacity 3 What is Earths Population Capacity Population Capacity 2 Population Capacity 3 Water UsePopulation Capacity 3 Population Capacity 4 Competition for scarce resourcesPopulation Capacity 4 Population Capacity 5 todays populationPopulation Capacity 5 Population Capacity 6 Future EffortsPopulation Capacity 6 Women Having Fewer Babies but Not Few Enough to Stabilize the Worlds Population Fertility rate Replacement-level fertility rate Total fertility rate (TFR) Several Factors Affect Death Rates (1) Life expectancy & Infant mortality rate Why are people living longer and fewer infants dying? Increased food supply and distribution Better nutrition Medical advances Improved sanitation Several Factors Affect Death Rates (2) U.S. infant mortality rate high due to Inadequate health care for poor women during pregnancy and their infants Drug addiction among pregnant women High birth rate among teenagers Migration Affects an Areas Population Size Economic improvement Religious freedom Political freedom Wars Environmental refugees No one knows if the population on Earth will double again. Although the number of additional people on Earth continues to increase each year, the rate at which the population is growing each year, the growth rate, is slowing. Infant Mortality: number of deaths by age 1 per 1000 live births in the population USA Average6.6 Sweden 2.4 France3.6 Afghanistan166 Infant Mortality (all values from 2005) USAAverage6.6 African-Americans 13.6 Native Americans8.9 Washington, D.C.11.4 Mississippi10.5 Louisiana9.8 Utah4.8 New Hampshire3.8 Singapore2.3 Sweden3.1 Bolivia54 Burundi106 Angola188 Age Structure The age structure of a population is usually shown graphically The population is usually divided up into prereproductives, reproductives and postreproductives The age structure of a population dictates whether is will grow, shrink, or stay the same size Age Structure Diagrams Positive Growth Zero Growth Negative Growth (ZPG) Pyramid Shape Vertical Edges Inverted Pyramid Disparities Developed countries 16% of the worlds population Control 81% of the worlds wealth Low-income developing countries 41% of the worlds population Control 3.4% of the worlds gross national income Difference in per capita income: 62 to 1! Population Increase in Developed and Developing Countries Population Data for Selected Countries (Table 5-3) CountryTotal Fertility Rate Doubling Time (Years) World2.854 Developing Countries Developed Countries Different Populations, Different Problems Human pressure on the environment caused by three factors Population size Affluence Technology Ecological Footprints by World Region The average American places at least 20 times the demand on Earths resources as does an average person in Bangladesh Fig. 5.7 here Global Conditions for a Sustainable Population Lower fertility rates (stabilize population) Consumption must decrease Protect the environment (stewardly action must increase) Consequences of Population Growth and Affluence The developing countries Affluence Developing or Developed Nations? High fertility rates High consumptive lifestyles: use 80% of worlds wealth Intense poverty Eat high on the food chain Developing or Developed Nations? Long doubling times High environmental degradation Twenty percent of the worlds population Basic Human Needs Drinkable Water Edible Food Safe Housing Health Care An Education A Job Growing Cities Consequences of Exploding Populations in the Developing World Consequences of Exploding Populations More Population Causes MORE LESS deforestation resource depletion loss of agricultural land biodiversity disease pest resistance population migration irrigation wetlands Affluence in the United States Consume the largest share of 11 of 20 major commodities Eat more than three times the global average in meat Lead the world in paper consumption Environment improves with increasing affluence Affluence in the United States Enables wealthy to clean up immediate environment by transferring waste to more distant locations. Affluent isolate themselves and unaware of the environmental stresses caused by their consumptive lifestyles. Dynamics of Population Growth Population profiles Future populations Population momentum The demographic transition Population Profiles of the United States Population Profile for United States Note increasing elderly population. Future World Populations Future United States Populations Projecting Future Populations: Developed Countries Population Projections: Developing Nations Comparing Projected Populations (see Fig. 5-17) Fertility Rate > 2 Fertility Rate < 2 Population Momentum Countries like Iraq will continue to grow for 5060 years even after the total fertility rate is reduced to replacement level. The Demographic Transition Demographic Transition Comparisons By the Year out of 117 countries will not be able to feed their own people One billion people will be living in cities that cannot support its inhabitants 400 million more women will be in need of child spacing services Basic Human Needs Drinkable Water Edible Food Safe Housing Health Care An Education A Job The Developing Countries Reform the system of land ownership Intensify cultivation of existing land to increase production per unit area Open new land to farm Move to cities and seek employment Engage in illicit activities for income Move to other countries How do these solutions aggravate the problems? Growing Cities Consequences of Exploding Populations in the Developing World Consequences of Exploding Populations More Population Causes MORE LESS deforestation resource depletion loss of agricultural land biodiversity disease pest resistance population migration irrigation wetlands