Key Issue 2Key Issue 2

Where has the world’s Where has the world’s population increased?population increased?

Population ChangePopulation Change

Geographers Geographers measure population measure population change in a country change in a country or the world as a or the world as a whole through three whole through three measures:measures:• Crude Birth RateCrude Birth Rate• Crude Death RateCrude Death Rate• Natural Increase Rate Natural Increase Rate

(NIR or NRI)(NIR or NRI)

WHY ARE THESE WHY ARE THESE IMPORTANT? IMPORTANT? • What do they tell us What do they tell us

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

Crude Birth/Death RateCrude Birth/Death Rate Crude means the Crude means the

world as a wholeworld as a whole

CBR Definition:CBR Definition:• Total # of live births in Total # of live births in

a year for every 1,000 a year for every 1,000 peoplepeople

• Example:Example: CBR of 20 =CBR of 20 =

• 20 births per 1,000 in 20 births per 1,000 in a 1 year perioda 1 year period

CDR Definition:CDR Definition:• Total # of deaths in a Total # of deaths in a

year for every 1,000 year for every 1,000 peoplepeople

Natural IncreaseNatural Increase

NIR definition:NIR definition:• % by which a % by which a

population grows each population grows each yearyear

• Formula:Formula: CBR- CDR = NIRCBR- CDR = NIR

• 20 – 5 = 15 20 – 5 = 15 • =1.5% NIR=1.5% NIR

Natural increase Natural increase means migration is means migration is excludedexcluded

World NIRWorld NIR• Early 21Early 21stst century = century =

1.2%1.2%• All time peak in 1963 All time peak in 1963

with 2.2%with 2.2%

80 million people 80 million people added annuallyadded annually• Even though NIR is Even though NIR is

slowing, population slowing, population base is large base is large

Doubling TimeDoubling Time

Rate of NIR effects Rate of NIR effects doubling timedoubling time

Definition:Definition:• # of years needed to # of years needed to

double a populationdouble a population• ExampleExample

NIR of 1.2 = 54 years to NIR of 1.2 = 54 years to doubledouble

If world NIR remains If world NIR remains steady through 21steady through 21stst century world century world population will be 24 population will be 24 billion by 2100billion by 2100

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

saharan Africa and saharan Africa and Middle EastMiddle East

Population ExplosionPopulation Explosion

• The population The population continues to “explode” continues to “explode” as the doubling time as the doubling time decreases. decreases.

• Example: Example: 8 A.D. – 250 million8 A.D. – 250 million

1650 A.D.- 500 million1650 A.D.- 500 million

1820 A.D.- 1 billion1820 A.D.- 1 billion

1930 A.D.- 2 billion1930 A.D.- 2 billion

1975 A.D.- 4 billion1975 A.D.- 4 billion

FertilityFertility

Total Fertility RateTotal Fertility Rate• Measures the # of births in Measures the # of births in

societysociety• Average # of children a Average # of children a

woman will have during woman will have during childbearing years (15-49 childbearing years (15-49 years)years)

• CBR provides picture of CBR provides picture of society for given yearsociety for given year

• TFR attempts to predict TFR attempts to predict future behavior of future behavior of individual womenindividual women

World TFR = 2.6World TFR = 2.6• Sub-saharan Africa =6Sub-saharan Africa =6• Western Europe= .09Western Europe= .09

MortalityMortality Two useful measuresTwo useful measures

• CDRCDR• Infant mortality rateInfant mortality rate

Definition:Definition:• # of deaths of infants under 1 # of deaths of infants under 1

year of age per yearyear of age per year

IMR rates highest in poorer IMR rates highest in poorer countriescountries• Sub-Saharan AfricaSub-Saharan Africa• 100 means 10% of all babies100 means 10% of all babies• Often reflect’s countries Often reflect’s countries

healthcare systemhealthcare system

U.S. special exampleU.S. special example• high MRI for a MDChigh MRI for a MDC• Why? Why?

Minorities, poor population access to Minorities, poor population access to healthcarehealthcare

Death RateDeath Rate

Death rate is not a good statistic to Death rate is not a good statistic to use in determining quality of life.use in determining quality of life.

Why?Why?• Not all countries are at same Not all countries are at same stagestage….….

Example: US is wealthy MDC but may have Example: US is wealthy MDC but may have more deaths because of an older population more deaths because of an older population than Ethiopia. than Ethiopia.

Life ExpectancyLife Expectancy Definition:Definition:

Average # of years a Average # of years a newborn infant can expect newborn infant can expect to live at current mortality to live at current mortality levelslevels

• Like all mortality/fertility Like all mortality/fertility rates higher in core/MDC rates higher in core/MDC nationsnations

Western Europe = 80 yearsWestern Europe = 80 years Sub-Saharan Africa= 50 Sub-Saharan Africa= 50

yearsyears

All become repetitious All become repetitious because all follow similar because all follow similar patternspatterns

Population Population Growth CurvesGrowth Curves

S CurveS Curve – historical – historical growthgrowth

J CurveJ Curve – – exponential growth exponential growth (fixed percentage)(fixed percentage)