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Increasing Human Population

The Greatest Environmental Problem

Spring 2012, Lecture 2

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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

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United Nations Population Division – 2012 EstimatesYear 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

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2050 Population EstimatesYear 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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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

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Significant Developments and Human Population

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Recent Population Explosion

• Detailed look at the last thousand years

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Global Fertilizer use

Crop Yield and Fertilizer Input“Green revolution”:

• high-yielding crop varieties

• chemical fertilizers

• pesticides

• irrigation

• mechanization

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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

New South Wales, Australia

13Figure shows the trend in the total catch for marine fisheries in NSW since 1984–85.

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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

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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

Source: Postel, S. "Carrying capacity: Earth's bottom line." State of the World, 1994.

1990 2010Total

Change (%)Per Capita Change (%)

Population (millions) 5,290 7,030 33

Fish Catch (million tons) 85 102 20 -10

Irrigated Land (million hectares) 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

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Regional population patterns:Population density

Consortium for International Earth Science Information Network.

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Doubling Times

World 40 yearsAfrica 23 yearsKenya (fastest) 20 yearsLatin America 30 yearsAsia 36 years

Doubling Time Map - 2000

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Worldwide Fertility, 2005

21• Children per woman

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Reduction in Childhood Death Rates

• DDT used against mosquitoes that transmit malaria

• Childhood immunization used against cholera, diphtheria, etc.

• Antibiotics used against bacterial infections

Demographic Transitions

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• 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 stays the same; this causes the natural rate of increase to increase rapidly

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Demographic Transition -Sweden

“Rate of Natural Increase”

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Demographic Transition -Mexico

“Rate of Natural Increase”

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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 – post-reproductive

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People over 100 years old in U.S.

4,000 in 1970

People over 100 years old in U.S.

• 79,086 in 201029

People over 100 years old in U.S.

30Projected 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 - 1989Share 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, 1992)

Global Income Distribution Graphic

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Global Wealth Pyramid, 2011

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Food Distribution Animation

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http://vimeo.com/moogaloop.swf?clip_id=8812686

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: 5.011995: 1.84

Population still growing!

Population in 2000: 1.3 billion Projected for 2025: 1.5 billion

Use of abortion Forcible abortions and sterilizationInfanticide

Criticisms:

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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2000: 1,006,300,297

India

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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 transmitted diseases.

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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

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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

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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