Transcript 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. emmigration
- 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
http://blue.utb.edu/paullgj/geog3320/lectures/populationgeography.html
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.
http://globalsoc.wordpress.com/2008/04/18/demographic-transition-theory/
•
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