Brief answer and informal responses OK here. This is all related to the Alley reading this week and our learning in class. Some of this we have discussed together. Other things you will need to find yourself in Alley's book. Feel free to email or talk to Trish and/or Dana if you want help in thinking these through. You are encouraged to use the online collection of resources related to this material.

1. What are some of the scientific challenges in reading the past from proxies? How do scientists cope with some of these problems? In answering these questions, you need not discuss all problems noted by Alley; just pick several problems discussed by Alley in his book Two-Mile Time Machine (1-2 short paragraphs of informal writing).

2. Briefly discuss how Alley uses the analogy for the freeze-thaw-freeze cycle of a pot roast to help us understand how Greenland ice borehole measurements read climate temperature back in time.

3. Which proxy measurements, in which locations and on what kind of "earth's garbage", allow scientists to go the farthest back in time to read the climate history?

4. Which geological and chemical processes conspire to keep earth's climate over millions and billions of year stable enough (despite the climate changes we'll focus on in this course) to keep lots of water in the liquid phase?

5. Why is Greenland such a great place for taking ice core measurements that yield information about past climates? (see Alley's book)

6. Briefly, what has just been learned from the fossilized collections of pack rats (called "middens") about the Younger Dryas event in the Grand Canyon? (See Science News article passed out in class Thursday)

7. The ocean conveyor belt is often called an "amplifier" or "globalizer" for climate change. What is meant by this?

Questions above are due Monday Oct. 3. The ones below will be due later (TBA).

8. What happens to the density of ocean water as temperature and salinity change? How does this help you understand the sinking of cold water in the north Atlantic part of the "ocean conveyor belt"?

9. What is the best explanation we've got that explains the ice ages that are spaced about 100,000 years apart?

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