Population growth and urbanizationPresentation Transcript
POPULATION GROWTH AND URBANIZATION L I M I T S O F P O P U L A T I O N G R O W T H S T R AT E G I E S F O R L I M I T I N G H U M AN P O P U L A T I O N G R O W T H U R B AN I Z A T I O N
VARIABLES THAT GOVERN POPULATION SIZE• Increase population size: births and immigration (individuals move INTO area).• Decrease population size: deaths and emigration (individuals move OUT of area).• Population Change = (Birth + immigration) – (Deaths + Emigration)
NO POPULATION CAN GROWTH INDEFINITELY• Environmental resistance: combination of all factors that act to limit the growth of a population.• Carrying Capacity: maximum population of a given species that a particular habitat can sustain indefinitely.• Food, Water, space dwindles as carrying capacity is reached: growth rate decreases.
HUMAN POPULATION• Past 200 years human population has grown exponentially (J-curve).• 3 Factors: Humans developed ability to expand into almost all climate zones and habitats.• Agriculture provided increased and steady food supply.• Death rates dropped due to sanitation and medicine.
HUMAN POPULATION• Currently 6 billion people on planet Earth.• Estimated 9 billion by 2050.• Cultural Carrying Capacity: Maximum number of people earth could support at reasonable level of comfort and freedom without impairing the planet’s ability to sustain future generations in the same way.• http://planetgreen.discovery.com/videos/focus- earth-too-many-people.html
HUMAN POPULATION GROWTH• Total Fertility Rate: the average number of children born to women in a population during their reproductive years.• US population is 3rd largest in world (1. China, 2. India).
BIRTH RATES AND FERTILITY RATES• Importance of children to workforce (birth rates higher in developing countries).• Cost of raising and educating children (birth rates lower in developed countries).• Care in old age (no pensions in developing countries- depend on children for care).• Urbanization (better access to family planning)• Education and employment of women.• Average age at marriage.• Religious and cultural beliefs.
DEATH RATES• Life expectancy : 77 years developed, 67 developing• Infant Mortality: higher in developing countries (4 million per year).• Higher in US than Europe: inadequate healthcare of poor women, drug addiction, high birth rate among teens.
HOW CAN WE SLOW HUMAN POPULATION GROWTH?• Economic development: demographic transition – as countries become industrialized populations grow more slowly• Family Planning: educational and clinical services.• Empowering Women: education, ability to control fertility, employment opportunities.• Controversial Ideas: http://planetgreen.discovery.com/videos/focus- earth-no-more-children.html
URBANIZATION: 4 TRENDS• 1. The proportion of the global population living in urban areas is increasing.• 2. The number and sizes of large urban areas is mushrooming.• 3. Urban growth is much slower in developed countries than in developing countries.• 4. Poverty is becoming increasingly urbanized, mostly in developing countries. http://planetgreen.discovery.com/videos/blood- sweat-takeaways/
URBAN SPRAWL• Definition: The growth of low-density development on the edge of cities and towns.• Problems: Eliminates surrounding agricultural and wild lands.• Inadequate mass transit = driving further = more pollution = loss of nonrenewable resources.• Economic death of many central cities.
REASONS FOR URBAN SPRAWL• Affordable Land• Relatively cheap gasoline (for the commute)• Poor Urban planning• Larger lot sizes• Single family homes• Lower crime rate• Newer public schools
URBAN SPRAWL EFFECTS ON NATURAL CAPITAL• Degradation of land and biodiversity• Loss of cropland• Loss of forests• Loss of grasslands• Loss of wetlands• Loss and Fragmentation of wildlife habitats
URBAN SPRAWL: DEGRADATION OF WATER• Increased use of surface and ground water• Increased run off and flooding• Increased water pollution• Decreased NATURAL sewage treatment.
URBAN SPRAWL: ENERGY, AIR, AND CLIMATE• Increased energy use and waste• Increased air pollution• Increased greenhouse gas emissions• Can enhance climate change.
URBAN SPRAWL: ECONOMIC EFFECTS• Decline of downtown businesses.• Increased unemployment in central city.• Loss of tax base in central city.