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? • What do they tell us

about the world? Increase in population Predict how quickly Population trends

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

Natural Increase

NIR definition:• % by which a

population grows each year

• Formula: CDR- CBR = 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

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 by 24 billion

More than 95% of NIR is clustered in LDCs• Exceeds 2.0 in sub-

saharan Africa and Middle East

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

Fertility

World NIR map similar to World CBR map

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

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

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.

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