Chapter 6 The Human Population and Its Impact

6-1 How Many People Can the Earth Support? Concept 6-1 We do not know how long we can continue increasing the earth’s carrying capacity for humans without seriously degrading the life-support system that keeps us and many other species alive.

Core Case Study: Slowing Population Growth in China: A Success Story 1.3 billion people…estimated to grow to 1.5 billion by ____________ Promotes one-child families with benefits like better _____________, free ________________, and salary _____________ Contraception, abortion, sterilization Fast-growing economy – growing ______________ Serious resource and environmental problems…ecological footprint will be _____________ 2025 housing health care bonuses middle class too large

Crowded Street in China Figure 6.1: Hundreds of people crowd a street in China. Almost one of every five persons on the planet lives in China, and the country’s resource use per person is projected to grow rapidly as China becomes more modernized and wealthy. Fig. 6-1, p. 125

Human Population Growth Continues but It Is Unevenly Distributed (1) For most of our history, the human population has grown _______________. slowly Reasons for human population increase? Movement into new habitats and ____________ zones Early and modern ______________ methods Control of infectious ____________ through…. sanitation systems, antibiotics, vaccines, health care climate agricultural diseases

Human Population Growth Continues but It Is Unevenly Distributed (1) Most population growth over last 100 years due to drop in ______________ rates death

Annual Growth Rate of World Population, 1950-2010 The world’s annual growth rate or our ___________ of growth has ___________ But we are still growing exponentially at a rate of about ________ per year = ________ million new people per year speed decreased 6-2 1.21% 83 Fig. 6-2, p. 127

Geographically our growth is _____________________ distributed… unevenly 10 9 8 7 World population (in billions) 6 5 4 Population in less-developed countries 3 2 1 Figure 6.3: Most of the world’s population growth between 1950 and 2010 took place in the world’s less-developed countries. This gap is projected to increase between 2010 and 2050. (Data from United Nations Population Division, The 2008 Revision and Population Reference Bureau, 2010 World Population Data Sheet) Population in more-developed countries 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year Population growth in developing countries is increasing _________ times faster than developed countries 9 Fig. 6-3, p. 127

Human Population Growth Continues but It Is Unevenly Distributed (2) Experts who study population growth are called _________________ By 2050, they are projecting our human population to be somewhere in between _________________ billion people. Why such a big range? There are countless factors that may affect the growth of a country or region demographers 7.8 and 10.8

Science Focus: Projecting Population Change Demographers must: Determine the ________________ of current estimates Some countries have poor knowledge of their population size Some deliberately inflate or deflate their population size due to __________________ or _________________ issues Make assumptions about ______________ trends…will women have more or fewer babies? Deal with different databases made by a ______________ of organizations… UN projections , U.S. Census Bureau, IIASA, World Bank reliability political economic fertility variety

World population (in billions) 11 UN high-fertility variant (2008 revision) U.S. Census Bureau (2008 update) 10 UN medium-fertility variant (2008 revision) IIASA (2007 update) UN low-fertility variant (2008 revision) World population (in billions) 9 8 7 Figure 6.A: This graph shows world population projections to 2050 from three different organizations: the UN, the U.S. Census Bureau, and IIASA. Note that the upper-most, middle, and lower-most curves of these five projections are all from the UN, each assuming a different level of fertility. 6 2010 2020 2030 2040 2050 Year Fig. 6-A, p. 128

Five Most Populous Countries, 2010 and 2050 Figure 6.4: This chart shows the populations of the world’s five most populous countries in 2010 and 2050 (projected). In 2010, more than one of every three persons on the earth lived in China (with 19% of the world’s population) or India (with 17%). (Data from United Nations Population Division) Fig. 6-4, p. 127

Science Focus: How Long Can The Human Population Keep Growing? Thomas ______________ was one of the first individuals to study the effects of population growth…. In 1798, he noticed that the human population was growing _________________ while our food supplies were growing at slower, ______________ rate. He thought that humans would soon reach their carrying capacity he was probably correct…but then the ________________ and ____________________ revolutions occurred Malthus exponentially linear industrial agricultural

Science Focus: How Long Can The Human Population Keep Growing? Scientists recognize that there is a difference between __________________ and ___________________ Will technology increase human carrying capacity? Can the human population grow indefinitely? To answer these questions, we must consider our ________________ carrying capacity… the maximum number of people who can live in reasonable ___________ and ______________ without decreasing the ability of earth to sustain future generations overpopulation overconsumption cultural freedom comfort

Natural Capital Degradation: Altering Nature to Meet Our Needs While people have different views on what our cultural carrying capacity should be, most agree that our current population growth has ____________ natural systems altered Figure 6.B: This list describes eight major ways in which we humans have altered natural systems to meet our growing population’s resource needs and wants (Concept 6-1). See an animation based on this figure at CengageNOW. Questions: Which three of these impacts do you believe have been the most harmful? Explain. How does your lifestyle contribute directly or indirectly to each of these harmful impacts?

Review Question 1 What are three major factors that account for the exponential increase in human population growth? Moving into new climates/habitats Figure 6.B: This list describes eight major ways in which we humans have altered natural systems to meet our growing population’s resource needs and wants (Concept 6-1). See an animation based on this figure at CengageNOW. Questions: Which three of these impacts do you believe have been the most harmful? Explain. How does your lifestyle contribute directly or indirectly to each of these harmful impacts? Agricultural technology Improved sanitation and health care

Review Question 2 Which has had the greatest effect on our growth rate? a. Increase in births b. Decrease in births c. Increase in deaths d. Decrease in deaths Figure 6.B: This list describes eight major ways in which we humans have altered natural systems to meet our growing population’s resource needs and wants (Concept 6-1). See an animation based on this figure at CengageNOW. Questions: Which three of these impacts do you believe have been the most harmful? Explain. How does your lifestyle contribute directly or indirectly to each of these harmful impacts?

Review Question 3 What are some factors that make population studies difficult? Unreliable data Fertility rates may change Figure 6.B: This list describes eight major ways in which we humans have altered natural systems to meet our growing population’s resource needs and wants (Concept 6-1). See an animation based on this figure at CengageNOW. Questions: Which three of these impacts do you believe have been the most harmful? Explain. How does your lifestyle contribute directly or indirectly to each of these harmful impacts? Different organizations /different methods