GL 107 Earth Systems Science

K. Hannula

Discussion questions for 12/3/07

1.  How is "climate" different from "weather"?

"Climate" refers to generalizations about patterns of weather -- variations in temperature and precipitation. It can refer to local variations (for instance, the climate of the southwestern US vs. the climate of Alaska), or it can refer to global weather patterns ("climate change").

2. Look at Fig. 20.6 in your textbook. Why is the Atacama Desert on the west coast of South America, and the Patagonian Desert on the east coast of South America? Explain the reasons why the other deserts of the world exist where they do.

The Atacama Desert, on the west coast of South America, lies within the tropical belt of northeast trade winds. The prevailing winds blow from the northeast, carrying moisture from the Atlantic Ocean over the Andes. The Atacama Desert lies in the rain shadow of the Andes.

The Patagonian Desert lies in eastern South America, but because it lies within the mid-latitude belt of westerly prevailing winds, it also lies in the rain shadow of the Andes. Where the winds blow from the west, they dump their moisture on the western slopes of the Andes, and leave the eastern side of the mountains dry.

3. Give one example of a positive feedback mechanism (a natural process that makes temperatures rise faster than they otherwise would) and a negative feedback mechanism (a natural process that slows the increase in temperature).

Positive feedback: melting of ice caps causes more sunlight to be absorbed by the earth's surface, which raises temperatures, which causes more melting of the ice caps.

Negative feedback: heating of the oceans increases evaporation of water, which increases the cloudiness of the sky. If the clouds reflect sunlight back into space, they will cool the earth's surface, which would cool the oceans and reduce the amount of evaporation and the number of clouds.

4. Out of the following sources of energy, which release carbon dioxide? (Petroleum, coal, natural gas, nuclear power, biomass, hydroelectric, geothermal, wind, solar.) What are the pros and cons (including, but not restricted to, CO₂ release) associated with using each energy source? Could any of those pros and cons change through time?

Release carbon: petroleum, coal, natural gas, biomass.

Do not release carbon: nuclear power, hydroelectric, geothermal, wind, solar.

(The other questions are food for thought, but we did not discuss them in class.)

5. If you wanted to be "carbon-neutral," how would you have to change the way you live?

(Food for thought... the answer will probably be different for every person.)