Population Clock Population Clock The global population reached 6 billion in fall of 1999.

Population Clockhttp://www.census.gov/main/www/popclock.html

The global population reached 6 billion in fall of 1999

Expansion of habitat Increased capacity in existing habitats Importing resources Improved sanitation and medicine Increase in agricultural technology

Availability of food and water Invasion of parasites, pathogens, or

disease Over-crowding Sudden Climate changes Pollution of air, soil and water If we do not take steps to control

population it is likely one of these factors will forcibly reduce our population for us!!

Population: number of persons Population change: increase in the

number of persons (per year) Growth rates: rate of change (per year)

includes births, deaths and immigration, and emigration

Crude Birth Rate (CBR)= number of births per 1000 population 1990: 24 Today: 21.3

Crude Death Rate (CDR)= number of deaths per 1000 population 1990: 9 Today: 8.93

Rate Natural Increase is % growth rate without migration

RNI = (crude birth rate – crude death rate) 10

1990: 1.5% Today: 1.4% growth rates have come down

Number of years in which a population doubles its size

Doubling time can be approximated using growth rates and the rule of 70

Doubling time (T) = ___70_____ % growth rate

Calculate Doubling Time Below rate: 1.4% doubling time = 50 years rate: 2.0% doubling time = ______ years rate: 0.5% doubling time= _______ years rate: -0.5% doubling time = _______years

Human Population Growth Per Year = 1.4% LEDC (least economically developed

country)=1.7% MEDC (more economically developed

country) = 1.0%

TFR (total fertility rate) = number of children born to a woman

during her reproductive years (or life time) 1990: 3.1 2000: 2.8

IMR (infant mortality rate) = infant deaths per 1000 live births (infant <

1 yr) Used as overall indicator of health 1990: 62 2000: 56 (1900: 200)

Use Ne(rt) formula N= Current population e= constant 2.71828… r = growth rate as a decimal!!! t = time in years

Example: 2010 data reports that a population of 2,350,000 has a growth rate of 1.2%. What will the population be in 2025?

The maximum population that can be sustainably supported without running out of resources.

MEDC’s LEDC’s

industrialized little or no industry

high GDP (gross domestic product)

low GDP

relatively rich populationprovide raw materials but few processed or manufactured goods

access to education and health care

limited access to education and health care

high resource use per capita

fewer resources consumed per person

low population growth ratesmost have high population

growth rates

Graphic device: bar graph Shows the age and gender composition

of a region Horizontal axis: gender

male: left-hand female: right-hand absolute number of people or %

Vertical axis: age 5-year or 10-year age groups

Three population categories Pre Reproductive- (0-14) Reproductive- (15-44) Post Reproductive- (45 +)

Helps to determine specifics of potential future populations

Shape of pyramid indicates future growth

Can point to future changes in social conditions of a country

StagePre-

industrial(Stage 1)

LEDC(Stage 2)

Wealthier LEDC

(Stage 3)

MEDC (Stage 4)

MEDC(Stage 5)

Birth rate

High High Declining Low Very low

Death rate

High Moderate Low Low Low

Life expect

Short Medium Long Long Long

Pop’l growth

Slow Rapid Slowing Stable Shrinking

Birth rates, death rates and growth rates systematically change through time as societies change: Modernize, urbanize Gain access to new technology Births, deaths, migration Fertility rates play huge role

Urbanization Importance of children in workforce Cost of raising a child Education/Employment for women Average age of marriage Availability of abortion Availability of birth control Religious beliefs, traditions and culture

High birth rates, high death rates, low growth rates

Stage for much of human history, traditional societies

Practically no country today

High birth rates, declining death rates, rising growth rates

Improvements in sanitation (water) and medicine

Europe during Industrial Revolution

LEDC countries since the 1950’s

Much of Africa today, some countries of Asia (Afghanistan, Nepal)

Continued decline of death rates, declining birth rates, growth rates decline from high to lower levels

Change in behavior: adaptation to lower death rate, in particular infant mortality rate

Economic change: urbanization (incentive to have fewer children)

Mexico today

Stage 4: low birth rates, low death rates, low growth rates United States today

Stage 5: low birth rates, rising death rates, declining growth rates (if birth rates drop below death rates: negative growth rates) Western Europe,

Japan

-500 -400 -300 -200 -100 0 100 200 300 400 500

0-4

5-9

10-14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85 OR

female

male

Stage 2: wide base

stage 3: wide middle

stage 4: slender

stage 5: narrow base

Computer simulations: Can be highly accurate with many variables Cant include unforeseen events (i.e. natural

disaster, terrorist strike, warfare)? Statistical and/or demographic tables

Include actual field measurements based on past trends.

Past trends may not always predict future trends. How large/representative are the sample

populations? Age/sex pyramids (

see above) Population curves

Mathematical extrapolation from graphs based on real data

Less complex than computer models