THE HUMAN POPULATION

HUMAN POPULATION AND CARRYING CAPACITY Current population ~6.8 billion a. due to: - improved sanitation - agriculture output - better living conditions Carrying Capacity - initially exponential until the limit is reached - limiting resources

FACTORS DRIVING POPULATION GROWTH A.Variables in Population Size - immigration v. emigration - Crude Birth Rate (CBR) * # of births per 1,000 people per year - Crude Death Rate (CDR) * # of deaths per 1,000 people per year - migration is not a factor (we don’t leave Earth)

B. Changes in Population Size - Global Population Growth Rate [CBR – CDR] 10 example: [20 – 8] = 1.2 percent 10 - National Population Growth Rate [(CBR + immigration) - (CDR + emmigration)] 10

- Doubling Time * based on constant growth rate * rule of 70 example) population grows at a 2 percent per year 70/2 = 35 years

C. Fertility - total fertility rate (TFR) * estimate of the average number of children each woman will have during her childbearing years - replacement-level fertility * TFR required to offset the average number of deaths in a population so that the current population can remain stable * depends on country’s economic status (developed v. developing)

D. Life Expectancy - average number of years that an infant born can be expected to live - depends on: * healthcare * sanitation * living conditions * aging * disease (HIV) - infant mortality * # of deaths of children under 1 per 1,000 live births

E. Age Structure - 5-year increments - total area of all bars  size of whole population - population pyramid

F. Migration - aids in population growth - not used in calculation of total population size - net migration rate * difference between immigration and emigration in a given yer per 1,000 people in a country

THEORY OF DEMOGRAPHIC TRANSITION As a country moves from a subsistence economy to industrialization, it undergoes a predictable shift in population growth.

Family planning a. as the education levels of women is increasing, the number of children they have is decreasing b. “regulation of the number of offspring through the use of birth control”

ECONOMIC DEVELOPMENT 9 out of the 12 most populous nations are developing countries Top 3 a. China b. India c. US

IPAT Equation Impact = Population X Affluence X Technology Impact – overall environmental effect Population – direct effect on impact Affluence – created by economic opportunity Technology – can degrade or help environment

LOCAL, GLOBAL, AND URBAN IMPACTS a.Local - locally produced materials * overuse * environmental degradation * erosion, habitat loss b. Global - agriculture * affects carbon cycle

c. Urban - consumes ¾ earth’s resources - New York City - presents environmental challenges, but also have smaller ecological footrprints (ie. Public transportation)

GROSS DOMESTIC PRODUCT (GDP) Measure of nation’s wealth Value of all products and services produced in a year in a particular country - consumer spending - investments - government spending - exports minus imports Correlates with pollution levels