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Environmental Problems Lots of people mean lots of waste, lots of food, lots of babies, lots of energy, lots of houses, lots of roads, lots of cars, lots of. . . Population: Factors that affect population size • Birth rate • Death rate • Since we can’t leave the earth and hope there are no aliens coming to earth, emigration and immigration are not considered • annual rate of population growth is presently _____. • 1965 = 2% • 1993 = 1.7% Can the rate drop and the population still increase? • The world’s population was 3.2 billion in 1965 and the growth rate was 2% . The increase was 70 million. • The world’s population was 5.5 billion in 1993 and the growth rate was 1.7%. The increase was 94 million. Factors affecting birth rates and fertility rates • Average level of education and affluence • Urbanization - children as labor for family in rural homes • Cost of raising and educating children • Educational and employment opportunities for women • Infant mortality rate • Average marriage age • Access to birth control • Religious beliefs Factors affecting death rates • Better nutrition • Fewer infant deaths and longer average life expectancy • Improvements in medical and public health technology Population Age Structures • Age structure diagrams show the potential growth of a nation’s population. • Populations are divided into three age groups: prereproductive (0-14), reproductive (15-44), and post reproductive (45 - 85+). • Nations with a large number of pre reproductive population will _________. Demographic Charts with Population Numbers Population age structures Tracking the baby boomers Population prediction LDC & MDC 1985 1985 to 2025 Carrying capacity • Carrying capacity - is • Limiting factors the maximum control the carrying population that an area capacity: can support for an • food indefinite period • space • It is unknown what the • waste build up earth’s carrying • disease capacity is • clean water Population Questions • Why is it rational for a • Why are falling birth poor couple in India to rates not necessarily a have six or seven reliable indicator of children? What future population changes might induce growth trends? such a couple to • Do you believe there rethink their are physical limits to reproductive lives? human population growth on Earth?
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