1. Human Population Growth
SBI4U
Miss Richardson

2. Life Histories
Life history refers to events in an organism’s life. It includes:
age of reproductive maturity
type of survivorship
fecundity
life span
mortality

3. K-Strategists In general, humans are considered K-strategists:
Small number of offspring
Reproduce later in life
Provide ample parental care
Ecologists use the r/K selection theory to estimate growth patterns

4. Demography
Demography is the statistical study of factors that affect human populations
These factors include:
Birth rate
Death rate
Population growth
Population distribution
Movement
World Population 2008

5. Human Population Growth

6. Human Population Growth
The human population curve shows exponential growth
Population growth and size has been regulated by factors that affect other populations, such as food availability, disease, and predators
Technological advances have also influenced population sizes

7. Exponential Growth Birth rate: 30/1000 people per year
Death rate: 20/1000 people per year
The difference between these rates results in about 2% growth per year
Doubling time refers to the amount of time it takes for a population to double
With a current growth rate of 1.2% per year, the world’s population (7 billion) is expected to double in another 58 years

8. Demographic Transition Model
A model was proposed by Warren Thompson that correlates stages of economic development with changes in population.

9. Population Pyramids
Population pyramids are used by demographers to graph the age of a population and compare various populations.
They show the percentage of females and males in different age categories (typically 5 year intervals)

10. Population Pyramids Population Pyramid – Republic of Congo
Shows growth momentum (many young people)
Population Pyramid – Canada
Baby boomer bulge, negative growth structure

11. Carrying Capacity
All environments have a limit to what they can sustain
Today, the richest 20% of the population:
uses 86% of the world’s resources
Produce 53% of CO2 emissions
The poorest countries:
Use 1.3% of the world’s resources
Produce 3% of the CO2 emissions

12. Ecological Footprint
Measures the total amount of land needed to support one person
Includes 6 categories of demand:
Cropland
Grazing land
Fishing ground
Forest land
Carbon absorption land
Building area
Average ecological per person is 2ha/person (20000m2)

14. Biocapacity
The Earth’s carrying capacity for human population is referred to as available biocapacity
It includes:
Cropland
Grazing land
Fishing grounds
Forest land
Building area
Carbon-asbsorption land
Currently, the Earth’s ecological footprint exceeds the biocapacity by about 23%