Environmental Problems, Their Causes, and Sustainability 1

Population(2004)Populationprojected(2025)InfantmortalityrateLifeexpectancy6.7United States (highly developed)Brazil (moderately developed)Nigeria (less developed)179 million137 million33Total fertility2.0rate (TFR) 2.2%Populationunderage 15%Populationoverage 6512%6%3%Per capitaGDP PPP $7,450$80021%211 million206 million294 million349 million77 years71 years52 years30%5.744%Figure 10-17 Comparison of key demographic indicators in2004 for three countries, one highly developed (United States),one moderately developed (Brazil), and one less developed(Nigeria). (Data from Population Reference Bureau)100$36,110is being followed by the echo-boom generation consistingof people born since 1977.From these few projections, we can see that anybooms or busts in the age structure of a population createsocial and economic changes that ripple through asociety for decades.What Are Some Effects of Population Declinefrom Reduced Fertility? Sliding Down a HillToo Fast Can HurtRapid population decline as a result of more olderpeople and fewer young people can lead to longlastingeconomic and social problems.The populations of most of the world’s countries areprojected to grow throughout most of this century. By2004, however, 40 countries had populations that wereeither stable (annual growth rates at or below 0.3%) ordeclining. All are in Europe, except Japan. This meansthat about 14% of humanity (896 million people) livesin countries with stable or declining populations. By2050, the United Nations projects, the population sizeof most developed countries (but not the UnitedStates) will have stabilized.As the age structure of the world’s populationchanges and the percentage of people age 60 or olderincreases (Figure 10-19), more countries will begin experiencingpopulation declines. If population declineis gradual, its harmful effects usually can be managed.But rapid population decline, like rapid populationgrowth, can lead to serious economic and socialproblems. A country undergoing rapid population declinebecause of a “baby bust” or “birth dearth” has aAgeAgeAgeAgeFemales504080+706060MalesFemales80+70605040MalesFemales60504080+70MalesFemales80+70605040Males195530201008 4 4812162020 1612Millions302010012 1620819858 4 420 1612 24Millions242015302010012 162088 4 420 1612 24Millions24302010012 1620820358 4 420 1612 24Millions24Figure 10-18 Tracking the baby-boom generation in the United States. (Data from Population ReferenceBureau and U.S. Census Bureau)186 CHAPTER 10 Applying Population Ecology: The Human Population