Environmental Science Ch. 6
How are urban areas growing?
-people are pulled in search of jobs, food, housing, better health care, entertainment, education, etc. -people are pushed by factors such as famine, loss of land, deteriorating environmental conditions, war, religious, racial, and political conflicts
Demographic transition model: Pre-Industial Stage
1 -Harsh living conditions- food shortages, malnutrition, lack of sanitation, poor health care, *-high birth and death rates
3 major factors for the rapid population growth
1) early and modern agriculture allows us to feed more people 2) technologies helped us expand all of the planet's climate zones and habitats 3) death rates dropped sharply because of improved sanitation and health care and development of antibiotics and vaccines that help us control disease
3 phases of the urbanization shift in the U.S.
1) people migrated from rural areas to large central cities 2) many people migrated from large central cities to smaller cities and suburbs 3) many migrated from the North and East to the South and West
World life expectancy for most of human history
35-40 years
Demographic transition model: Postindustrial Stage
4 -sustainable forms of economic development -ZPG achieved -population size may decline slightly
Where is human population density high?
coastal areas, along rivers, in temperate latitudes
Life Expectancy
useful indicator of the overall health of a population, the average number of years a person can be expected to live
Demographic trap?
-conditions, especially abundance of resources, were very different than today -population growth in LDC's may exceed economic development and overwhelm local life support systems
urban sprawl impact on economy
-decline of downtown business districts -more unemployment inc central cities
Human population growth impact on natural capital
-decreased biodiversity -increased use of NPP -increased genetic resistance in pest species and disease causing bacteria -eliminating many natural predators -introducing harmful species -disrupting natural chemical cycling and energy flor -relying mostly on polluting and climate-changing fossil fuels
9 factors that affect birth and fertility rates
-importance of children as a part of the labor force (need to haul water, gather wood, find food, etc. for their family to survive) -cost of raising and educating children -the ability, or lack of, private and public pension systems (couples need less children to support them when older) -urbanization, those in rural areas tend to have more children because they are a family resource and have less access to family planning -educational and employment opportunities available for women -average age at marriage/of first child -availability of legal abortions and reliable birth control methods -religious beliefs, traditions, & cultural norms
urban sprawl impact on energy, air, and climate
-increased energy use and waste -increased emissions of CO2 and other air pollutants
Major Changes in the U.S.
-increased life expectancy -increased married women working outside the home -increased high school graduates -increased homes with flush toilets -increased people living in suburbs -increased hourly wages -increased homicides per year
Fertility rates per region
-largest in least developed countries -large in less-developed countries -high in the world -lowest in more-developed countries
Populations grow/decline based on what 3 factors?
birth, death, and migration
urban sprawl impact on biodiversity
-loss of cropland -loss of fragmentation of forests, grasslands, wetlands, and wildlife habitat
Dramatic decrease of death rates in the past century
-nutrition -infrastructure, water & sanitation -education and medical care
urban sprawl impact on water
-increased use and pollution of surface and groundwater -increased runoff and flooding
% of people living in urban areas
1850: 2% 2013: 52% 2050: 67%
Demographic transition model: Industrializing/ Transitional Stage
2 -Industrialization begins -food production rises -health care improves -rapid population growth *-death rates drop *-birth rates remain high
What is replacement level fertility ?
2.1 children per couple
What is the world average fertility rate?
2.6
Demographic transition model: Industrial Stage
3 -industrialization widespread -children expensive to raise -opportunities for women -advantageous to delay children -populations continue growing *-birth rates drop, death rates remain about the same
As of 2015, the size of the human population was
7.3 billion
By 2015, the size of the human population is most likely to be
9.7 billion
how close are we to the environmental limits for population growth?
?
The history of human population graph
J shaped curve - exponential, the growth rate is decreasing but human population is still growing -for most of history it grew slowly but in the last 200 years it began growing very rapidly
What country has the highest life expectancy?
Japan
Who developed the demographic transition model?
data from western European nations that industrialized during the 19th century
Poverty in urbanized areas
increasing, especially in LCD's
Wide base diagram
indicates built-in momentum, large people under 15 (in the pre-reproductive stage), population will grow for one lifetime after fertility drops to replacement level
Why are death rates dropping?
people are living longer and fewer infants are dying because of 1) larger food supplies 2) improvements in food distribution 3) better nutrition 4) medical advances 5) improved sanitation 6) safer water supplies
Age structure diagrams
plotting the numbers of the population in the 3 reproductive categories 1) pre-reporductive: 14 and under 2) reproductive: 15-44 3) post-reproductive: 45+
Two demographic worlds
population growth is unevenly distributed, growing faster and more people in LDC's than in MDC's
What is the most important factor affecting life expectancy?
poverty
the urban sprawl
the growth of low-density development on the edges of cities and towns
What is the main cause for the urban sprawl?
the mass production of automobiles
Total fertility rate
the number of births per women during reproductive years
Crude birth rate
the number of births per year per 1000 people, not adjusted for number of women in the reproductive stage
