Human Population Growth
Human Population Growth Basic concepts and human history
Human population has recently exploded in size Note large increase in late 20th century
Human evolution Changes in society cause changes in population Human ancestor numbers regulated by the environment like any other organism Homo sapiens sapiens (modern humans) around 90,000 years old
Agricultural revolution Began 10,000 - 12,000 y.a. in the Middle East
Hunter-gatherers Small nomadic populations Short life expectancy (30-40 yrs.) LOW ENVIRON. IMPACTS Small numbers Frequent movements
Societal effects Ample food available Frees individuals from daily food gathering Craftsmen and artisans arise Class distinctions
Fundamentally alters human civilization
Better survival rates
1
Agricultural revolution
This changes everything... POPULATION DENSITY: Populations remain in one location Ample food = population growth
Permanent settlements arise...
PEOPLE IN CITIES NEED: Architecture improves...
...CITIES ARE BORN
Fields for farming & grazing, water, wood, clay, minerals, etc. ENVIRONMENTAL IMPACTS: Increased human populations stress local environment
Industrial revolution
Menderes Valley in modern Turkey
Erosion in river valley
Begins in Europe in early 18th century
Overgrazing Over-farming Deforestation
CHANGES Agriculture Production Transportation
Delta into Aegean grows over time
Industrial revolution STEAM POWER: Coal-fired Replaces water power Factories need not be near water Powers factories, railroads, sea travel
SOCIETY
Industrial revolution AGRICULTURE: Crop rotation - reduced fallow time Plowing and seeding techniques improved Root crops popularized Late 1800's inorganic fertilizer produced Mechanized farming and processing END RESULT:
More food from less land with less labor
2
Revolutions and pop. growth
Industrial revolution
Each of these revolutions raised the carrying capacity for humans
Urbanization of population Plentiful food Medicine and sanitation reduce mortality Mass production improves quality of life END RESULT:
Numbers of humans
SOCIAL CONSEQUENCES:
Industrial – Scientific revolution
Agricultural revolution Tool-making revolution
Populations rise rapidly Time
Population growth curve A highly simplified and somewhat unrealistic growth model
Number
…eventually leveling off at the carrying capacity Note the human population is still in the rapid growth phase
…then rapidly...
Population grows slowly...
CARRYING CAPACITY Maximum no. of a species the environment can support
Figure 3.12
Time
THE BIG QUESTION:
Where will the human population level off?
Human carrying capacity QUESTION:
How many humans can the earth support?
50 billion Assumes: All open flat land cultivated Purely vegetarian diet People live underground
→
2.5 billion Assumes: Current food production Typical American diet
World grain production leveling off Population continues to increase Per-capita grain production necessarily declines http://www.unfpa.org/modules/6billion/facts.htm
Environmental impact starting to cause problems
3
Calculating growth rate BIRTH RATE:
Births per unit time divided by population size b = birth rate B = number of births per unit time N = total population size
b = B /N
DEATH RATE: Deaths per unit time divided by population size d = birth rate D = number of births per unit time N = total population size
d = D/N
GROWTH RATE: g = (B - D)/N
Rate of population change
AN EXAMPLE: Population of Australia in 1998 (N) = 18,700,000 Births from 1998-1999 ( B) = 261,500 Deaths from 1998-1999 (D) = 130,900
BIRTH RATE: b = B /N DEATH RATE: d = D/N
b = 261,000/18,700,000 b = 0.014 b = 1.4% d = 130,900/18,700,000 d = 0.7%
GROWTH RATE: g = (B - D)/N g = (261,800 - 130,900)/18,700,000 g = 0.7%
Variables as above
DOUBLING TIME
POPULATION GROWTH:
Time it takes population size to double
Pop size time 2 = Pop size time 1 + (Pop size time 1 * growth rate time1 )
Varies depending on growth rate
Using the previous example:
N 2 = N 1 *(1+ g1)
Population of Australia in 1998 (N1 ) = 18,700,000 Roughly equal to 70 ÷÷ growth rate
Figure 5.5
Even g =1% will double global population in your lifetime
Growth rate of Australia in 1998 (g1 ) = 0.7% or 0.007 Population of Australia in 1999 (N2 ) = ?
N2 =
18,700,000 *(1.000 + 0.007)
N2 =
18,700,000 + 130,900
N2 =
18,830,900
FACTORS AFFECTING POPULATION GROWTH N 2 = N 1 *(1 + g1) Population increase affected by population size and growth rate
Therefore:
Large population = rapid increase High growth rate = rapid increase Population size
China = 1,220,000,000 people x 1% growth = +12,200,000 per yr Japan = 126,000,000 people x 1% growth = + 1,260,000 per yr Growth rate Japan =126,000,000 people x 1% growth = + 1,260,000 per yr Japan =126,000,000 people x 10% growth = + 12,600,000 per yr
4
Human population has recently exploded in size Note large increase in late 20th century
Human evolution Changes in society cause changes in population Human ancestor numbers regulated by the environment like any other organism Homo sapiens sapiens (modern humans) around 90,000 years old
Agricultural revolution Began 10,000 - 12,000 y.a. in the Middle East
Hunter-gatherers Small nomadic populations Short life expectancy (30-40 yrs.) LOW ENVIRON. IMPACTS Small numbers Frequent movements
Societal effects Ample food available Frees individuals from daily food gathering Craftsmen and artisans arise Class distinctions
Fundamentally alters human civilization
Better survival rates
1
Agricultural revolution
This changes everything... POPULATION DENSITY: Populations remain in one location Ample food = population growth
Permanent settlements arise...
PEOPLE IN CITIES NEED: Architecture improves...
...CITIES ARE BORN
Fields for farming & grazing, water, wood, clay, minerals, etc. ENVIRONMENTAL IMPACTS: Increased human populations stress local environment
Industrial revolution
Menderes Valley in modern Turkey
Erosion in river valley
Begins in Europe in early 18th century
Overgrazing Over-farming Deforestation
CHANGES Agriculture Production Transportation
Delta into Aegean grows over time
Industrial revolution STEAM POWER: Coal-fired Replaces water power Factories need not be near water Powers factories, railroads, sea travel
SOCIETY
Industrial revolution AGRICULTURE: Crop rotation - reduced fallow time Plowing and seeding techniques improved Root crops popularized Late 1800's inorganic fertilizer produced Mechanized farming and processing END RESULT:
More food from less land with less labor
2
Revolutions and pop. growth
Industrial revolution
Each of these revolutions raised the carrying capacity for humans
Urbanization of population Plentiful food Medicine and sanitation reduce mortality Mass production improves quality of life END RESULT:
Numbers of humans
SOCIAL CONSEQUENCES:
Industrial – Scientific revolution
Agricultural revolution Tool-making revolution
Populations rise rapidly Time
Population growth curve A highly simplified and somewhat unrealistic growth model
Number
…eventually leveling off at the carrying capacity Note the human population is still in the rapid growth phase
…then rapidly...
Population grows slowly...
CARRYING CAPACITY Maximum no. of a species the environment can support
Figure 3.12
Time
THE BIG QUESTION:
Where will the human population level off?
Human carrying capacity QUESTION:
How many humans can the earth support?
50 billion Assumes: All open flat land cultivated Purely vegetarian diet People live underground
→
2.5 billion Assumes: Current food production Typical American diet
World grain production leveling off Population continues to increase Per-capita grain production necessarily declines http://www.unfpa.org/modules/6billion/facts.htm
Environmental impact starting to cause problems
3
Calculating growth rate BIRTH RATE:
Births per unit time divided by population size b = birth rate B = number of births per unit time N = total population size
b = B /N
DEATH RATE: Deaths per unit time divided by population size d = birth rate D = number of births per unit time N = total population size
d = D/N
GROWTH RATE: g = (B - D)/N
Rate of population change
AN EXAMPLE: Population of Australia in 1998 (N) = 18,700,000 Births from 1998-1999 ( B) = 261,500 Deaths from 1998-1999 (D) = 130,900
BIRTH RATE: b = B /N DEATH RATE: d = D/N
b = 261,000/18,700,000 b = 0.014 b = 1.4% d = 130,900/18,700,000 d = 0.7%
GROWTH RATE: g = (B - D)/N g = (261,800 - 130,900)/18,700,000 g = 0.7%
Variables as above
DOUBLING TIME
POPULATION GROWTH:
Time it takes population size to double
Pop size time 2 = Pop size time 1 + (Pop size time 1 * growth rate time1 )
Varies depending on growth rate
Using the previous example:
N 2 = N 1 *(1+ g1)
Population of Australia in 1998 (N1 ) = 18,700,000 Roughly equal to 70 ÷÷ growth rate
Figure 5.5
Even g =1% will double global population in your lifetime
Growth rate of Australia in 1998 (g1 ) = 0.7% or 0.007 Population of Australia in 1999 (N2 ) = ?
N2 =
18,700,000 *(1.000 + 0.007)
N2 =
18,700,000 + 130,900
N2 =
18,830,900
FACTORS AFFECTING POPULATION GROWTH N 2 = N 1 *(1 + g1) Population increase affected by population size and growth rate
Therefore:
Large population = rapid increase High growth rate = rapid increase Population size
China = 1,220,000,000 people x 1% growth = +12,200,000 per yr Japan = 126,000,000 people x 1% growth = + 1,260,000 per yr Growth rate Japan =126,000,000 people x 1% growth = + 1,260,000 per yr Japan =126,000,000 people x 10% growth = + 12,600,000 per yr
4
