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Key Issue 2

Key Issue 2 . Where has the world’s population increased?. Population Change. Geographers measure population change in a country or the world as a whole through three measures: Crude Birth Rate Crude Death Rate Natural Increase Rate (NIR or NRI). WHY ARE THESE IMPORTANT?

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Key Issue 2

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  1. Key Issue 2 Where has the world’s population increased?

  2. Population Change • Geographers measure population change in a country or the world as a whole through three measures: • Crude Birth Rate • Crude Death Rate • Natural Increase Rate (NIR or NRI) • WHY ARE THESE IMPORTANT? • What do they tell us about the world? • Increase in population • Predict how quickly • Population trends

  3. Crude Birth/Death Rate • Crude means the world as a whole • CBR Definition: • Total # of live births in a year for every 1,000 people • Example: • CBR of 20 = • 20 births per 1,000 in a 1 year period • CDR Definition: • Total # of deaths in a year for every 1,000 people

  4. Natural Increase • NIR definition: • % by which a population grows each year • Formula: • CBR- CDR = NIR • 20 – 5 = 15 • =1.5% NIR • Natural increase means migration is excluded • World NIR • Early 21st century = 1.2% • All time peak in 1963 with 2.2% • 80 million people added annually • Even though NIR is slowing, population base is large

  5. Doubling Time • Rate of NIR effects doubling time • Definition: • # of years needed to double a population • Example • NIR of 1.2 = 54 years to double • If world NIR remains steady through 21st century world population will be 24 billion by 2100 • More than 95% of NIR is clustered in LDCs • Exceeds 2.0 in sub-saharan Africa and Middle East

  6. Population Explosion • The population continues to “explode” as the doubling time decreases. • Example: • 8 A.D. – 250 million • 1650 A.D.- 500 million • 1820 A.D.- 1 billion • 1930 A.D.- 2 billion • 1975 A.D.- 4 billion

  7. Fertility • Total Fertility Rate • Measures the # of births in society • Average # of children a woman will have during childbearing years (15-49 years) • CBR provides picture of society for given year • TFR attempts to predict future behavior of individual women • World TFR = 2.6 • Sub-saharan Africa =6 • Western Europe= .09

  8. Mortality • Two useful measures • CDR • Infant mortality rate • Definition: • # of deaths of infants under 1 year of age per year • IMR rates highest in poorer countries • Sub-Saharan Africa • 100 means 10% of all babies • Often reflect’s countries healthcare system • U.S. special example • high MRI for a MDC • Why? • Minorities, poor population access to healthcare

  9. Death Rate • Death rate is not a good statistic to use in determining quality of life. • Why? • Not all countries are at same stage…. • Example: US is wealthy MDC but may have more deaths because of an older population than Ethiopia.

  10. Life Expectancy • Definition: • Average # of years a newborn infant can expect to live at current mortality levels • Like all mortality/fertility rates higher in core/MDC nations • Western Europe = 80 years • Sub-Saharan Africa= 50 years • All become repetitious because all follow similar patterns

  11. Population Growth Curves • S Curve – historical growth • J Curve – exponential growth (fixed percentage)

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