Population Dynamics

Presented by:

From T.A. Blakelock High School

Introduction

• Person 1

• Person 2

Human Population Growth• You will create a graph of human population

growth and use it to predict future growth.

Year # of People

1650 0.50

1750 0.70

1850 1.0

1925 2.0

1956 2.5

1966 3.3

Year # of People

1970 3.6

1974 3.9

1976 4.0

1980 4.4

1991 5.5

2000 6.0

2004 6.4

Did Your Graph Look Something Like this?

Graph Analysis• It took 1649 years for the world population to double, going

from .25 billion to .5 billion people. How long did it take the population to double again?

• Answer: 200 years• How long did it take to double a second time?• Answer: 75 years• A third time?• Answer: 51 years• Based on your graph, how many years will it take the population

of 2004 to double again?• Answer: perhaps near 2050 it would reach 14 billion people.• What factors contributed to the world’s overall population growth?• Answer: industrialization, health care, sanitation, etc.

What would happen if today’s population doubled? How

would this affect our Earth?

Carrying Capacity• When populations have limited

resources, they tend to experience a period of slow growth at the beginning, then a period of rapid growth, but as the resources become limited, the growth rate slows.

• Eventually, a population will reach the point where the birth rate equals the death rate. This is known as the carrying capacity.

• Carrying capacity can change over time depending on food supplies, disease, weather, predation, etc.)

• How does this graph compare to the one you drew?

• What is Earth’s carrying capacity?

• What happens when we reach Earth’s carrying capacity?

Ecological Footprint

• So far humans have been able to alter Earth’s carrying capacity, but for how much longer?

• Ecological Footprint: the amount of productive land that is required for each person in a defined area for food, water, transportation, housing, waste management, etc. The average per person globally is 2 hectares of land.

• We are now going to roughly calculate each of our footprints…

How Can We Help?

• In small groups, come up with ways that you and your family can decrease your footprint.

• Pick two of your favourites to share with the class.

THANKS FOR LISTENING!!!

• Any Questions?