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Unit 3: Human Population. The Anthropocene Epoch. Is named for the alterations to the Earth’s crust as a result of human activity Industrial Revolution Atomic Age. World Population. Is 7.1 billion people Has increased exponentially over the past 10,000 years - PowerPoint PPT Presentation
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The Anthropocene Epoch
• Is named for the alterations to the Earth’s crust as a result of human activity– Industrial Revolution– Atomic Age
World Population
• Is 7.1 billion people• Has increased exponentially
over the past 10,000 years• Has stopped growing as
quickly– May start decreasing by 2100
Human Carrying Capacity of the Earth
• Is estimated between 4 and 16 billion
• Depends on how we use resources
• Depends on how quickly the population grows
Age Structure
• Expresses how a population is divided among age groups
• Can show how a population is and will be affected by birth rates and life expectancy
Demographic Transition
• Is a change in birth and death rates over time
• Occurs as nations industrialize
• Overall leads to a decline in population growth
Demographic Transition
• Stage 2– Death rates drop due to
improvements in medical care and sanitation
– Birth rates remain high– Population grows
Demographic Transition
• Stage 3– Birth rates drop due to
increased education and better employment
– Population growth rate slows
Demographic Transition
• Stage 4– Birth and death rates
remain low due to economic stability
– Population stays stable
Life Expectancy Affects Population Growth
• Longer-lived individuals delay having children– Can result in fewer children per couple
• Increased numbers of older individuals can become a burden on younger members of a population
Disease Affects Population Growth
• Epidemics like influenza can increase the death rate• Diseases like AIDS can decrease life expectancy
Birth Rates Affect Population Growth
• Total Fertility Rate (TFR)– Estimated number of children each woman in a population
will have
• If this number drops below the number of children needed to replace their parents, the population will shrink
Birth Rates Affect Population Growth
• Replacement-Level Fertility– # of births required to offset deaths– Must take into account pre-
reproductive mortality• Individuals who die before reproducing
– In developed nations, it is 2.1– In developing nations, it is higher
Migration Affects Population Growth
• Only occurs between countries, not the planet
• A positive migration indicates a country’s population is growing– More people are entering
the country than leaving it
Achieving Zero Population Growth
• Depends on controlling birth rates– Education (sex education
and general education)– Access to birth control– Delaying age of first
childbearing
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