Population & Environment
II
ES 118 Spring 2008
Life expectancy
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20th Century saw global transformation
of human health
– Worldwide, average life expectancy rose
from 40 to 65.5 years (projected to reach
74 by 2050)
– In India in 1900, average life expectancy
around 23 years; by 2000 this had tripled
– In US increased from 47 to 77 years
Life expectancy
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Factors influencing include:
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Better nutrition
Improved sanitation
Clean water
Education
Access to health and medical services
Strongly correlated with income to about
$4,000/person, then level out at about 75
years for men and 85 for women
www.gapminder.org
Contraceptive revolution
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For many, the concept of planning the
number and timing of their children
revolutionary
By 2000, more than half of the world’s
women of reproductive age using a modern
family planning method
Early attempts to influence fertility focused
on smaller family size and family planning
…but access still limited
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½ billion people live in countries where
<10% of women use an effective
contraception
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Largely rural and agriculture-based
Low per capita income
Economic crises
Waning international support
Examples: Nigeria (8%), Afghanistan,
Ethiopia, Mali, Democratic Republic of
Congo
Social and political factors
influencing fertility
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Some countries used restrictive
policies, penalizing families with “too
many” children
Policy response shifting to broader
issues (“social determinants of
health”):
– Maternal and child health
– Recognition of importance of gender
and links between poverty, gender
roles, inequality, and health
– Education, sanitation,
transportation, clean water
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UN Millennium Goals target many of
these issues
Education
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Kerala, India
– One of poorer
states in India, but
India's highest life
expectancy and
lowest infant
mortality rates
– High literacy rates,
especially among
women
www.gapminder.org
Mortality
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Rapid growth in world’s population in
last century caused largely be decline
in crude death rates
Time
Maternal health
HIV/AIDS
Between 2000-2050, AIDS projected to
cause premature deaths of 278 million
people in 53 countries—38 in Africa
Malaria
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Why is Malaria getting worse?
– Drug resistance
– Environmental and social change
(poverty, dams, irrigation, deforestation,
war, lack of basic sanitation…)
– Cost of control
Case Studies
The case of cities
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We are now an urban planet
– 1900: 10% of global population
– 2008: >50% of world’s 6.6b people
and growing
Growing cities
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By 2030,~ 5 billion people
will live in cities
More than 95% of net
increase in the global
population will be in cities in
developing world, mostly in
Asia
Largest “mega-cities” are
growing to unprecedented
sizes, but most do not live in
mega-cities
R. Mace Science 319, 764 -766 (2008)
Environmental impact of
cities
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Hot spots of production, consumption, and
waste generation
<3% of land surface but
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78% of global carbon emissions
60% of residential water use
76% of wood for industrial purposes
Huge “ecological footprints”
Cities thus present both problems and
solutions to sustainability challenges in an
increasingly urban world
The case of Asia
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Pace of economic change in India and
China is breathtaking
– Fastest growing middle-classes in the
world
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These two countries will have a
profound impact on the world’s
environment
China
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China’s economy has averaged a
9.5% growth rate
Approximately 80% of Wal-Mart’s
suppliers are now located in China
China is starting to build one of the
world’s largest automobile industries
Steel consumption US and China 19902003
http://www.earth-policy.org/Updates/Update45_data.htm
Meat consumption US and China 19602004
http://www.earth-policy.org/Updates/Update45_data.htm
The Challenge of Food
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People in poor countries typically eat at lower trophic
levels than rich countries
– 90% of energy of plants lost when converted to protein from
animals
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People in countries like US eat too much
(“overnutrition”)
– 50% of North Americans overweight
– 25% obese
– Ecological impact of 1 person eating at carnivore level = 10
people living at herbivore level
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What happens as countries like China become
wealthier and want more meat?
Environmental impact
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Extreme pollution
– 16 of 20 cities in the world with most
polluted air in China
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Access to resources
– China: Just 8% of world’s fresh water for
22% of world’s population
– India: 17% of world’s population and 2.3%
of land resources
The Future
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Lessons of last ½ Century have shown
that countries can undergo rapid and
radical social and demographic
change
– Fertility rates can drop from 7 to 2
children in less than 2 generations
– Birth rate remains single most potent
determinant of global population growth
– We know much more, but prediction
difficult
How many people?
Key questions for future
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Can the world provide an adequate
standard of living for 2.5 billion more people
without causing widespread environmental
damage?
How do we address increased:
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Waste
Pollution
Competition with other organisms for space
Energy and climate change
What is the earth’s carrying capacity?