Richard T. Wright Environmental Science Tenth Edition Chapter 5 The Human Population Copyright 2008 Pearson Prentice Hall, Inc. KEY TOPICS Human population expansion and its cause Different worlds Consequences of population growth and affluence Dynamics of population growth
5.1 Human Population Expansion and Its Cause Reasons for the patterns of growth Biotic potential exceeds environmental resistance: birth rates exceed death rates There are 6.7 billion people on Earth If each one stood up, pronounced their name and sat down It would take 600 years to complete roll call By 2025 it will take 1,000 years to complete this exercise World Population Over the Centuries 9,000 human beings added to the planet every hour
Reasons for the Human Population Explosion Causes of disease recognized Improvements in nutrition Discovery of antibiotics Improvements in medicine Increase in number of women who actually reach child-bearing age Short doubling times in some countries World Population Growth and Absolute Growth
Population Projections Based on Different Fertility Assumptions 11.7 b Gradual decline in fertility in developing countries. 2.02 children/woman ½ child lower than medium projection ½ child higher than medium projection 9.1 b Maintain fertility rate of 2.6 children/woman
Growth versus carrying capacity What population level can the planet support sustainably? 5.2 Different Worlds on One Planet Rich nations, poor nations Population growth in rich and poor nations Different populations, different problems
Major Economic Divisions of the World Gross national income/capita Economic Categories Based on Per Capita Gross National Income ( World Bank) High-income, highly developed, industrialized countries United States, Japan, Canada Average GNI per capita = $28,550 Middle-income, moderately developed countries Latin America, South Africa, China Average GNI per capita = $1,920 Low-income, developing countries Western and central Africa, India, central Asia Average GNI per capita = $450
Disparities Developed countries 15% of the world s population Control 80% of the world s wealth Low-income developing countries 37% of the world s population Control 3.0% of the world s gross national income Difference in per capita income: 63 to 1! ~$28,550/$450 = 63.4 Human Development Index (UNDP) The United Nations Development Programs (UNDP) used HDI as measure of general well-being. HDI evaluation is based on Life expectancy Education Per capita income
Dimensions of the Human Poverty Index Different Populations, Different Problems IPAT Formula: calculates human pressure on the environment ( I = P x A x T) I = environmental impact P = population A = affluence and consumptive patterns T = level of technology in the society
Different Populations, Different Problems Environmental impact of developing countries due to P. Environmental impact of developed countries due to A and T. Both have some measure of I for different reasons. Average American places at least 20 times the demand on Earth s resources compared to a person in Bangladesh. Different Populations, Different Problems How does stewardship (S) affect the IPAT formula? S = wildlife conservation, pollution control, energy conservation, and recycling I = P x A x T S
Population Increase in Developed and Developing Countries 1.5% growth rate More than 98% of world population growth ~1.2 billion: 18% world pop, 0.1% growth rate Population Data for Selected Countries (Table 5-2) Country Total Fertility Rate Doubling Times (Years) World 2.7 58 Developing Countries Developed Countries USA 2.9 47 1.6 700 2.0 117
Different Populations, Different Problems Human pressure on the environment caused by three factors Population size: number overpopulation Affluence: consumption overpopulation Technology Global Conditions for a Sustainable Population Lower fertility rates (stabilize population) Consumption must decrease Protect the environment (stewardly action must increase)
5.3 Consequences of Population Growth and Affluence The developing countries Affluence 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? Consequences of Exploding Populations in the Developing World
Consequences of Exploding Populations MORE More Population Causes 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 or 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 5.4 Dynamics of Population Growth Population profiles Future populations Population momentum The demographic transition
Population Profile United States ECO Population Profile United States
Population Profile United States
Population Profiles of the USA and Italy USA ITALY 20% below 15 years Less than 20% below 15 years Population Projections United States Increased fertility rate of 2.0 and current migration Fertility rate of 1.8
Population Profile Developing Country IRAQ 40-50% below 15 years Population Profile Developing Country IRAQ Assuming a declining TFR to 2.7 in 2025
Population Momentum Effect of current age structures on future population growth Determined by percent of population in younger versus older age cohorts Positive Population Momentum It will take countries with a large base of younger population a long time to achieve stability. Countries like Iraq will continue to grow for 50-60 years even after the total fertility rate is reduced to replacement level.
Calculating Fertility Rates and Doubling Times (CBR - CDR)/10 = % Rate of Increase or decrease in population per year 70/ Rate of Increase = Doubling Time CBR CDR = Natural Increase
Demographic Transition Phases of Demographic Transition Phase I: primitive stability (CBR = CDR) Phase II: declining CDR, CBR remains high accelerating population growth Phase III: declining fertility rate, but significant population growth continues Phase IV: modern stability with low CBR and CDR
Demographic Transition Comparisons (Figure 5-17) Phase IV: developed countries Phases II and III: developing countries