Case Study 8-1 presented one author's view of greenhouse warming. This article, which appeared in Science, should be readily accessible. Read the article and answer the following questions. You may need to refer to other sections of this book and, per- haps, articles referenced by the author.

a. What assumptions and simplifications did the author make in the construction of the time-temperature variation curve? What steps did he take to validate his time-temperature curve?

b. Are there other variables, besides volcanic emissions, variations in solar radiation, and greenhouse gases, that could affect atmospheric temperature? Did the author satisfactorily account for these other possible variables?

c. How could 14C data from tree rings be used to reconstruct variations in solar radi- ation? You might want to refer to Chapter 6 for help in answering this question.

d. How did the author test his model for temperature variations, and what steps did he take to convince the reader that his model provided an appropriate representa- tion of future temperature variations?