Earth Science: Geology, the Environment, and the Universe

Chapter 27: Human Impact on Earth Resources

Problem of the Week

Human Carrying Capacity: What’s the Limit?

In this activity students should be encouraged to think about the carrying capacity of Earth and the rapidity at which the human population is increasing. The idea of humans going beyond our carrying capacity is probably a new one for most of them.

For further information and debate have them read the article at:

http://darwin.bio.uci.edu/~sustain/bio65/lec16/b65lec16.htm#HUMAN POPULATION GROWTH

and

http://www.chem.brown.edu/chem12/readings/atlantic/consume.html.

These articles present interesting statistics and opposing views.

Answers:

Things to Think About:

  1. Which environmental factors normally act as limiting factors? Food, water, shelter, and space
  2. What factors control or may control the limits of human populations? Food, water, shelter, and space. Clean water and air might, waste buildup and non-renewable resources, disease, wars, preserving the environment for other organisms, etc..
  3. Ways in which humans manipulate these factors to "outwit" nature. Some things we do:
    • use fertilizers and hormones to enhance food production and supplies;
    • ship foods and other supplies around the world to areas that can't sustain the population in that area;
    • build up to give ourselves more "room" when room in a city runs out;
    • treat, burn, and bury wastes to keep them from building up;
    • drill deep wells to extract water in aquifers;
    • recycle nonrenewable resources, such as aluminum and glass
    • continually make medical advancements to increase infant survival rates and increase life spans

To Do:

Population and Availability of Renewable Resources
 19902010(predicted change)Total % Change2030
1. Population (millions)52907,030339350
2. Fish Catch (million tons)8510220122
3. Irrigated Land (million hectares)23727717324
4. Crop Land (million hectares)14441,51651592
5. Rangeland and Pasture (million hectares)34023,54043682
6. Forests (million hectares)34133,165-72944

To find increases:
Data pieces 1 – 5
Predicted increase in 2030 at steady rate of change = 2010 predicted number ' the percentage + the 2010 predicted number.
Example:
Data piece 1:
X = 7030 X 0.33 = 2320 + 7030
X = 9350 (rounded to nearest ones place)

Data piece 6

Predicted change in 2030 at steady rate of change = 2010 predicted number – (2010 predicted number ' the percentage)

Example:
X = 3165 – (3165 X.07)
X = 3165 – 222
X = 2943

Resources:

  1. 1. 6 Billion Human Beings
    * A very cool site has a population "ticker" and students can enter their age and find out what the population was when they were born. There is also a tutorial like presentation discussing population parameters and phenomena. Site goes into some information on birth control that you may want to censor, or not, depending on age of students and purpose of using this site.
  2. Carrying Capacity Of the Earth
    Excellent article discussing how humans have thus far gone beyond the earth’s ability to support us.
  3. World Population Information
    US Census Bureau information.
  4. Do We Consume Too Much?
    Article presents and interesting twist on consumption debate.

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