1. a.  In the early 1970's, scientists described how the production of CFC's could gradually deplete the ozone layer, as has now been observed. Explain how this gradual depletion occurs.

b.  Scientists were, by contrast, surprised at the seasonal appearance of the ozone hole.  Explain what produces the ozone hole, and in particular why it appears where and when it does.

c.  In the future, stratospheric water vapor is expected to be more abundant, meaning that polar stratospheric clouds would be more common in both hemispheres.  What would this mean for the Antarctic ozone hole?
 

2.  Today, the concentration of atmospheric CO2 is about 370 parts per million by volume (ppmv).  If all the fossil fuel reserves were burned, what would the atmospheric CO2 concentration reach assuming

(a) all the fossil carbon went into the atmosphere
(b) the same fraction (roughly 46%) is absorbed by nature as at present

Note that this is not quite the same calculation as on page 261.

3.  In your own words, what do you consider the most compelling evidence to support the following statements by the IPCC (from the Summary for Policymakers (SPM) of Working Groups I and II).  Write just one sentence for each statement.

a.  "An increasing body of observations gives a collective picture of a warming world and other changes in the climate system."

b.  "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."

c.  The global average temperature will rise at least 1.5C during the 21st century. (be sure to include a discussion of the SRES scenarios, p. 18 of the SPM of Working Group I)

d.  "Anthropogenic climate change will persist for many centuries."

e.  Climate change has already affected many physical and biological systems.
 

4.   What are some adverse impacts expected from climate change?  What are some beneficial impacts?

5.  Explain the concept of adaptive capacity and give an example.  Why are developed countries like the U.S. more likely to have higher adaptive capacity than developing countries like Bangladesh?