Key Issue 2 Where has the worlds population

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

Population Change n 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) n WHY ARE THESE IMPORTANT? • What do they tell us about the world? n n n Increase in population Predict how quickly Population trends

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

Natural Increase n NIR definition: n • % by which a population grows each year • Formula: n • Early 21 st century = 1. 2% • All time peak in 1963 with 2. 2% CDR- CBR = NIR • 20 – 5 = 15 • =1. 5% NIR n World NIR Natural increase means migration is excluded n 80 million people added annually • Even though NIR is slowing, population base is large

Doubling Time n n Rate of NIR effects doubling time n Definition: • # of years needed to double a population • Example n NIR of 1. 2 = 54 years to double n If world NIR remains steady through 21 st century world population will by 24 billion More than 95% of NIR is clustered in LDCs • Exceeds 2. 0 in subsaharan Africa and Middle East

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

Fertility n World NIR map similar to World CBR map n 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 n World TFR = 2. 6 • Sub-saharan Africa =6 • Western Europe=. 09

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

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

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

Population Growth Curves n n S Curve – historical growth J Curve – exponential growth (fixed percentage)