Increasing Human Population

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Increasing Human Population
Increasing Human Population
The Greatest Environmental Problem
Spring 2012, Lecture 2
1
US Census Bureau Population
Estimate
Click link below to see Latest Census Bureau
Estimate of U.S. and World Populations
United State Population Clock
World Population Clock
2
3
United Nations Population
Division – 2012 Estimates
Year
Population
Year
Population
1950
2 529 229
2005
6 506 649
1955
2 772 982
2010
6 895 889
1960
3 038 413
2015
7 284 296
1965
3 331 007
2020
7 656 528
1970
3 696 186
2025
8 002 978
1975
4 076 419
2030
8 321 380
1980
4 453 007
2035
8 611 867
1985
4 863 290
2040
8 874 041
1990
5 306 425
2045
9 106 022
1995
5 726 239
2050
9 306 128
2000
6 122 770
In thousands
4
2050 Population Estimates
Year of
Estimate
Low variant
Medium
variant
High
variant
Constant
fertility
variant
2002
7 408 573
8 918 724
10 633 442
12 753 513
2005
7 679 714
9 075 903
10 646 311
11 657 999
2008
7 958 779
9 149 984
10 461 086
11 030 273
2012
8 112 191
9 306 128
10 614 318
10 942 544
In thousands
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6
7
Thomas Malthus (1798)
“An Essay on the Principle
of Population”
• Populations grow geometrically while supporting resources
grow arithmetically
• Population, if not purposefully checked (“preventative
checks”), would outpace resources and lead to unplanned
“positive checks” that would return population to sustainable
levels
8
Significant Developments and
Human Population
9
Recent Population Explosion
• Detailed look at the last thousand years
10
Crop Yield and Fertilizer Input
“Green
revolution”:
• high-yielding
crop varieties
• chemical
fertilizers
• pesticides
• irrigation
Global Fertilizer use
• mechanization
11
Humans Have:
• Transformed or degraded 39-50% of the
Earth's land surface
• Increased atmospheric CO2 concentration by
40%
• Overexploited or depleted 22% of marine
fisheries
• 44% more are at the limit of exploitation
12
New South Wales, Australia
Figure shows the trend in the total catch for marine fisheries in
NSW since 1984–85.
13
Changes Due to Man
• About 20% of bird species have become extinct in
the past 200 years, almost all of them because of
human activity
• Man uses more than half of the accessible surface
fresh water
• On many islands, more than half of plant species
have been introduced by man
• On continental areas, man has introduced 20% or
more of the plant species present
14
Human Activities
• Over 50% of terrestrial nitrogen fixation is
caused by human activity
• Use 8% of the primary productivity of the
oceans (25% for upwelling areas and 35%
for temperate continental shelf areas)
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Changes Due To Man
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Population and Availability of
Renewable Resources
1990 2010
Population (millions)
Fish Catch (million tons)
5,290 7,030
Total
Per Capita
Change (%) Change (%)
33
85
102
20
-10
237
277
17
-12
Cropland (million hectares)
1,444 1,516
5
-21
Rangeland and Pasture
(million hectares)
3,402 3,540
4
-22
Forests (million hectares)
3,413 3,165
-7
-30
Irrigated Land
(million hectares)
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Source: Postel, S. "Carrying capacity: Earth's bottom line." State of the World, 1994.
Regional population patterns:
Population density
Consortium for International
Earth Science Information Network.
18
Doubling Times
World
Africa
Kenya (fastest)
Latin America
Asia
40 years
23 years
20 years
30 years
36 years
19
Doubling Time Map - 2000
20
Worldwide Fertility, 2005
• Children per woman
21
Reduction in Childhood Death
Rates
• DDT used against mosquitoes that transmit
malaria
• Childhood immunization used against
cholera, diphtheria, etc.
• Antibiotics used against bacterial infections
22
Demographic Transitions
• When a country moves from stage 1 of the demographic model to stage 2,
a population explosion occurs
• This transition occurs when technology and medical care improvements
decrease a countries death rate dramatically while the birth rate stays23the
same; this causes the natural rate of increase to increase rapidly
Demographic Transition -Sweden
“Rate of Natural Increase”
24
Demographic Transition -Mexico
“Rate of Natural Increase”
25
National Age Structures
• The proportion of individuals in different age
groups has a significant impact on the potential
for future population growth
• Mexico – large fraction of young people likely
to reproduce in the near future
• Sweden – even distribution of population
through all age groups, and many people beyond
prime reproductive years
• United States – even distribution except for
bulge due to post WWII baby boom
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Age Structures
• Each horizontal bar is a five-year cohort
• Blue = pre-reproductive, yellow – reproductive, and orange – postreproductive
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People over 100 years old in U.S.
4,000 in 1970
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People over 100 years old in U.S.
• 79,086 in 2010
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People over 100 years old in U.S.
Projected 597,547 thousand in 2050
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Trends in U.S. Population
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2008 Population Projections
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Global Income Distribution, 1960 - 1989
Share of Global Income Going To:
Year
Richest 20%
Poorest 20 %
Ratio of richest
to poorest
1960
70.2
2.3
30 to 1
1970
73.2
2.3
32 to 1
1980
76.3
1.7
45 to 1
1989
82.7
1.4
59 to 1
Source: United Nations Development Programme, Human
Development Program, 1992 (New York, Oxford University Press,
34
1992)
Global Income
Distribution Graphic
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Global Wealth Pyramid, 2011
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Food Distribution Animation
http://vimeo.com/moogaloop.swf?clip
_id=8812686
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China - 20% of world’s population
• Potential for rapid population growth
• 2000: 1,263,637,531
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China: "one-child-per-couple"
policy since 1979
• Rewards for having only one child: grants, additional
maternity leave, increased land allocations. Children get
preferential treatment in education, housing, and
employment.
• Couples punished for refusing to terminate unapproved
pregnancies, for giving birth when under the legal
marriage age, and having an approved second child too
soon.
• Penalties include fines, loss of land grants, food, loans,
farming supplies, benefits, jobs and discharge from the
Communist Party.
• In many provinces sterilization is required after the couple
has had two children.
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China’s Population Policy
Children per woman:
1970: 5.01
1995: 1.84
Population still growing!
Population in 2000: 1.3 billion
Projected for 2025: 1.5 billion
Criticisms:
Use of abortion
Forcible abortions and sterilization
Infanticide
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China 2025
• Approaching stabilization
• 2025: 1,394,638,699
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China 2050
• Possible decline in population
• 2050: 1,303,723,332
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India
2000: 1,006,300,297
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India 2025
• 2025 predicted: 1.396.046.308
• The base is narrower than the top
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India 2050
• 2050 predicted: 1,656,553,632
• A definite “baby-boom” shape
• Note disparity male/female numbers
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U.N. Conference on Population (Cairo, 1994)
"Programme of Action" (182 nations)
Goal: to stabilize human population at 7.8 billion by 2050
1. Provide universal access to family-planning and reproductive health
programs.
2. Recognize that environmental protection and economic development are
not necessarily antagonistic. Promote free trade, private investment and
development assistance.
3. Make women equal participants in all aspects of society - by increasing
women's health, education, and employment.
4. Increase access to education. Provide information and services for
adolescents to prevent unwanted pregnancies, unsafe abortion, and the spread
of AIDS and sexually transmitted diseases.
5. Ensure that men fulfill their responsibility to ensure healthy pregnancies,
proper child care, promotion of women's worth and dignity, prevention of
unwanted pregnancies, and prevention of the spread of AIDS and sexually
46
transmitted diseases.
United Nations Population Fund
(UNFPA)
Programs to improve:
• Pre- and post-natal mother's health
• Access to voluntary family planning programs and
contraception
• STD and HIV education and prevention
• U.S. funding withheld for many years because of
UNFPA’s support of China’s policies
• U.S. funding restored for F.Y. 2000 at level of $25
million
47
Slowing Population Growth
• The HIV epidemic is measurably slowing
population growth
• Nowhere is this more evident than in sub-Saharan
Africa, a region of 800 million people, where the
epidemic is spiraling out of control
• If a low-cost cure is not found soon, countries with
adult HIV infection rates over 20 percent, such as
Botswana, South Africa, and Zimbabwe, will lose
one fifth or more of their adult population to AIDS
within the next decade
48
Slowing Population Growth
• When the United Nation's demographers did their
biennial update of world population numbers and
projections in October of 1998, they reduced the
projected global population for 2050 from 9.4
billion to 8.9 billion – in 2009, it is 9.1 billion
• Of this 500 million drop, two thirds was because
of falling fertility - that's the good news
• The bad news is that one third of the fall was the
result of rising mortality from AIDS
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