How Many People Can the Earth Support?

1
(No Transcript)
2
How Many People Can the Earth Support?

• We do not know how long we can continue
  increasing the earths carrying capacity for
  humans without seriously degrading the
  life-support system for humans and many other
  species.

3
Environmental science

• is the study of how the natural world works, and
  what is happening to it as the human population
  expands. It includes all of the natural sciences
  and sometimes economics and a few other social
  sciences.
• Major topics can be boiled down to
• Human population
• Energy all implications of its use including
  air pollution
• Resources-biological, water, mineral

4
What is environmental science? Knowing where
your water/food/energy come from and where
your waste goes
5
The single driving mechanism for all the
environmental problems we face in the world today
may be exponential growth.
6
Key Concepts

• Humans are subject to natural laws and ecological
  processes such as limiting factors.
• Significant differences in developed vs.
  developing worlds
• Unlimited use of natural resources is
  unsustainable
• There are a number of tools to understand
  populations project future outcomes

7
There are more people living on Earth today than
ever before in human history. Both the number
of people and the amount of overall consumption
exert an impact on the environment.
Wednesday Jan26
8
What is Earths Population Capacity
9
Population Trends over 200 yrs
10
Today 6.6B
www.prb.org
11
What Factors Influence the Size of the Human
Population?

• Population size increases because of births and
  immigration and decreases through deaths and
  emigration.
• The average number of children born to women in a
  population (total fertility rate) is the key
  factor that determines population size.

12
Population Size

• Natality
• Number of individuals added through reproduction
• Crude Birth Rate - Births per 1000
• Total Fertility Rate Average number of children
  born alive per woman in her lifetime
• Mortality
• Number of individuals removed through death
• Crude Death Rate Deaths per 1000

13
Calculating Population Change,
(Births Immigration) ( Deaths
Emmigration)
14
Demographic TransitionCalculating the increase
or decrease of a population
(CBR CDR)/10 Rate of increase or decrease in
population per 1,000 per year
Number of births or deaths/1000 so countries can
be compared. Crude because no consideration of
who is old or young
15
Calculating Doubling Times
70/Rate of Increase Doubling Time
The world rate of population increase is 1. How
long would it take to double the population?
70 years
16
Calculating increase (Fertility Rates) and
Doubling Times Practice
Calculate the Rates of increase and doubling
times
17
Calculating increase (Fertility Rates) and
Doubling Times Practice
18
End of WWII
Depression
Demographic Transition
Baby Boom..
Echo Baby Boom
19
Age Structure Diagrams
Positive Growth Zero Growth
Negative Growth (ZPG) Pyramid
Shape Vertical Edges Inverted
Pyramid
20
Population Profiles of the United States
21
(No Transcript)
22
Human Population Growth Continues but It Is
Unevenly Distributed

• Population growth in developing countries is
  increasing 15 times faster than developed
  countries
• By 2050, 97 of growth will be in developing
  countries
• Should the optimum sustainable population be
  based on cultural carrying capacity?

23

• Major concers that
• growing populations cause increased
  environmental stresses?
• Infectious diseases
• Biodiversity losses
• Water shortages
• Traffic congestion
• Pollution of the seas
• Climate change
• Population Capacity 3 BBC Water Use

24
What is Earths Population Capacity

• Population Capacity 2
• Population Capacity 3 Water Use
• Population Capacity 4 Competition for scarce
  resources
• Population Capacity 5 todays population
• Population Capacity 6 Future Efforts

25
Women Having Fewer Babies but Not Few Enough to
Stabilize the Worlds Population

• Fertility rate
• Replacement-level fertility rate
• Total fertility rate (TFR)

26
Several Factors Affect Death Rates (1)

• Life expectancy Infant mortality rate
• Why are people living longer and fewer infants
  dying?
• Increased food supply and distribution
• Better nutrition
• Medical advances
• Improved sanitation

27
Several Factors Affect Death Rates (2)

• U.S. infant mortality rate high due to
• Inadequate health care for poor women during
  pregnancy and their infants
• Drug addiction among pregnant women
• High birth rate among teenagers

28
Migration Affects an Areas Population Size

• Economic improvement
• Religious freedom
• Political freedom
• Wars
• Environmental refugees

29
No one knows if the population on Earth will
double again.

• Although the number of additional people on Earth
  continues to increase each year, the rate at
  which the population is growing each year, the
  growth rate, is slowing.

30
Infant Mortalitynumber of deaths by age 1 per
1000 live births in the populationUSA
Average 6.6Sweden 2.4France 3.6Afghan
istan 166
31
Infant Mortality (all values from
2005)USA Average 6.6 African-Americans
13.6 Native Americans 8.9Washington,
D.C. 11.4Mississippi 10.5Louisiana 9.8Ut
ah 4.8New Hampshire 3.8Singapore 2.3S
weden 3.1Bolivia 54Burundi 106Angola
188
32
Age Structure

• The age structure of a population is usually
  shown graphically
• The population is usually divided up into
  prereproductives, reproductives and
  postreproductives
• The age structure of a population dictates
  whether is will grow, shrink, or stay the same
  size

33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
Age Structure Diagrams
Positive Growth Zero Growth
Negative Growth (ZPG) Pyramid
Shape Vertical Edges Inverted
Pyramid
38
Disparities

• Developed countries
• 16 of the worlds population
• Control 81 of the worlds wealth
• Low-income developing countries
• 41 of the worlds population
• Control 3.4 of the worlds gross national income
• Difference in per capita income 62 to 1!

39
Population Increase in Developed and Developing
Countries
40
Population Data for Selected Countries (Table 5-3)
Country Total Fertility Rate Doubling Time (Years)
World 2.8 54
Developing Countries 3.5 37
Developed Countries 1.5 700
41
Different Populations, Different Problems

• Human pressure on the environment caused by three
  factors
• Population size
• Affluence
• Technology

42
Ecological Footprints by World Region

• The average American places at least 20 times the
  demand on Earths resources as does an average
  person in Bangladesh

Fig. 5.7 here
43
Global Conditions for a Sustainable Population

• Lower fertility rates (stabilize population)
• Consumption must decrease
• Protect the environment (stewardly action must
  increase)

44
Consequences of Population Growth and Affluence

• The developing countries
• Affluence

45
Developing or Developed Nations?

• High fertility rates
• High consumptive lifestyles use 80 of worlds
  wealth
• Intense poverty
• Eat high on the food chain

46
Developing or Developed Nations?

• Long doubling times
• High environmental degradation
• Twenty percent of the worlds population

47
Basic Human Needs

• Drinkable Water
• Edible Food
• Safe Housing
• Health Care
• An Education
• A Job

48
Growing Cities
49
Consequences of Exploding Populations in the
Developing World
50
Consequences of Exploding Populations
deforestation resource depletion loss of
agricultural land biodiversity disease pest
resistance population migration irrigation wetland
s
MORE
More Population Causes
LESS
51
Affluence in the United States

• Consume the largest share of 11 of 20 major
  commodities
• Eat more than three times the global average in
  meat
• Lead the world in paper consumption
• Environment improves with increasing affluence

52
Affluence in the United States

• Enables wealthy to clean up immediate environment
  by transferring waste to more distant locations.
• Affluent isolate themselves and unaware of the
  environmental stresses caused by their
  consumptive lifestyles.

53
Dynamics of Population Growth

• Population profiles
• Future populations
• Population momentum
• The demographic transition

54
Population Profiles of the United States
55
(No Transcript)
56
Population Profile for United States
Note increasing elderly population.
57
Future World Populations
58
Future United States Populations
59
Projecting Future Populations Developed Countries
60
Population Projections Developing Nations
61
Comparing Projected Populations (see Fig. 5-17)
Fertility Rate lt 2
Fertility Rate gt 2
62
Population Momentum

• Countries like Iraq will continue to grow for
  5060 years even after the total fertility rate
  is reduced to replacement level.

63
The Demographic Transition
64
Demographic Transition Comparisons
65
By the Year 2000

• 65 out of 117 countries will not be able to feed
  their own people
• One billion people will be living in cities that
  cannot support its inhabitants
• 400 million more women will be in need of child
  spacing services

66
Basic Human Needs

• Drinkable Water
• Edible Food
• Safe Housing
• Health Care
• An Education
• A Job

67
The Developing Countries

• Reform the system of land ownership
• Intensify cultivation of existing land to
  increase production per unit area
• Open new land to farm
• Move to cities and seek employment
• Engage in illicit activities for income
• Move to other countries

How do these solutions aggravate the problems?
68
Growing Cities
69
Consequences of Exploding Populations in the
Developing World
70
Consequences of Exploding Populations
deforestation resource depletion loss of
agricultural land biodiversity disease pest
resistance population migration irrigation wetland
s
MORE
More Population Causes
LESS