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Chapter 6


Environmental Science
Course Code
Carl Mitchell

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Chapter 6: Human Population
Central Case: Chinas One-child Policy:
Pop. of Earth is 6.7 billion as of 2008
One-child policy was put forth b/c as pop. kept growing and growing the resources in
China began to decline and peoples standard of living decreased…one-child policy made it
better for the government to control its social, economic, environmental challenges
Human population: approaching 7 billion
India is on course of surpassing China as the world most populated country
Pop. has doubled since 1966 and is growing roughly 80 million people/yr. (nearly 2.6
people are added—that is births minus deathsevery second)
Exponential growth—even if growth rate remains steady, population size will increase by
greater increments with each successive generation
Perspectives on human population have changed over time:
At the outset of industrial revolution in England of 1700s pop. growth was a good thing
ofor parents, a high birth rate meant more children to support them at old age
ofor society, it meant a greater pool of labour for factory work
Thomas Malthus: (1) favoured pop. growth as society industrialized (2) argued that the
pressure of pop. growth on the availability of resources could lead to disaster
Paul Ehrlich: predicted that the rapidly increasing human pop. would unleash
widespread famine and conflict that would consume civilization by the end of the 20th century
Is population growth really aproblem today?
World’s ongoing pop. growth is b/c of technological innovations, improved sanitation,
better medical care, increased agricultural output, and other factors that made death rates decline

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—especially drop in rates of infant mortality
Birth rates didnt decline as much…so births have outpaced deaths for many yrs. Now
Pop. growth is no problem for Malthusian and neo-Malthusian b/c they see enormous
increases in crop yields and advances in agricultural technology associated with the Green
Revolution as a good things
Technological fix: Environmental scientists recognize that few resources are actually
“created” by human, and that not all resources can be replaced or reinvested once they have been
depleted (i.e. once species go extinct, we cannot replicate their exact function in ecosystems, or
know what medicines we mightve obtained from them and so on…land is also an irreplaceable
Unless resource availability keeps pace with population growth, the average person in the
future will have less space in which to live, less food to eat, less material wealth that the average
person does today
Population increases are indeed a problem if they create stress on resources, social
systems, or natural environment such that our quality of life decline
Pop. is declining in Europe…maybe happening b/c of migration, refugeeism
Outside Europe 56% of national gvnts feel their birth rates are too high, and only 8% feel
they are too low
Pop. is one of the several factors that affect the environment:
oIncreased pop. intensifies impact on envir. as more individuals take up space, use natural
resources, generate waste
oIncreased affluence magnifies environmental impact through the greater per capita
resource consumption that generally has accompanied enhanced wealth
oChanges in tech. may either dec. or inc. human impact on the envir.
I=P*A*T*S…how sensitive a given environment is to human pressures
oArid lands of eastern China are more sensitive to human disturbance than the moist
regions of southeastern China

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We have employed technological advances to increase global agricultural production
faster than our population has risen
Although China reduced its air pollution…the country faces threat from automobiles
Application of pop. ecology principles to the study of statistical change in human
populations is the focus of the social science of demography
Demography is the study of human population:
Demographic data help us understand how differences in pop. characteristics and related
phenomena (for instance, decisions about reproduction) affect human communities and their
Demographers: study pop. size, density, distribution, age structure, sex ratio, rates of
birth, death, immigration, emigration of humans just as population ecologists study these
characteristics in other organisms
Population size: the absolute number of individuals
Population density and distribution:
Pop. density: numbers of people per unit of land area…high in regions with temperate,
subtropical, and tropical climates…low in regions with extreme-climate biomes, such as desert,
deep rainforest, tundra…dense along seacoasts and rivers…les dense at locations far from water
At intermediate scales, we cluster together in cities and suburbsspread more sparsely
across rural areas
At small scales, we cluster in certain neighbourhoods and individual households
Urbanization involves the packaging and transport of goods, intensive fossil fuel
consumption, and hotspots of pollution
ohowever, the concentration of people in cities increases efficiency and economies of
scale, and relieves pressure on ecosystems in less-populated areas by releasing some of
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