AOS/IES 171 - Prof. Hitchman Study Guide for 2nd Mid-Term Exam Tuesday, April 23, 2002 $_x$ means a subscript x as in HOx & NOx $_2$ means a subscript to as in H2O or Cl2 1. What is the consensus prediction of climate model forecasts for global surface warming in the year 2100? Describe some possible serious effects of a global surface warming of +3 K. 2. Observations indicate an increase in average global surface temperature over the last century. By how much? What other factors besides an enhanced greenhouse gas loading could possibly account for this? 3. The role of clouds in an enhanced greenhouse gas scenario is highly uncertain. Would you expect nights to become warmer or colder if there were more clouds? What would an increase in high clouds do to the average temperature? What would an increase in low clouds do? 4. What is the ice-albedo feedback? In an enhanced greenhouse gas scenario, would you expect greater temperature changes at low or high latitudes? If the globe were to warm, what two main factors would contribute toward a rise in sea level? What aspect of Antarctica might actually contribute to a drop in sea level? 5a. What ingredients are need to make ozone? What are the two main effects of ozone absorbing ultraviolet light? Why is tropospheric ozone a problem? Compare the amounts of ozone in the troposphere and stratosphere. Why is column ozone largest near the poles? Why is there usually less ozone over the south pole than over the north pole? 5b. What reaction creates ozone? What are HO$_x$, NO$_x$, ClO$_x$, and BrO$_x$? What are the primary surface source gases that supply these families in the stratosphere? What is a catalytic destruction cycle? What is the observed trend in ozone in the tropics and in the middle latitudes from 1979 to 1995? What probably caused it? 6a. What gas in large volcanic eruptions leads to the stratospheric aerosol layer? What is the aerosol layer made of? How can the aerosol layer affect the stratospheric ozone layer? In which directions does the Brewer-Dobson circulation transport the aerosol and ozone? 6b. Where and when do ice crystals form in the stratosphere? What are the resulting clouds called? In the dark, ``heterogeneous" reactions near the surfaces of the ice crystals create Cl$_2$. What happens when the sun comes up in the springtime? How did the eruption of Mt. Pinatubo in July 1991 lead to the biggest ozone hole ever (300 $\rightarrow$ 90 Dobson Units) in October 1993? 7a. Where does the N and S come from that make NO$_2$ and SO$_2$ during burning? What is the ``tropospheric cleanser" that converts these to nitric and sulfuric acid? List three effects of sulfuric acid in the troposphere. How could an increase in greenhouse gases, plus an increase in SO$_2$ output cause a reduced diurnal temperature range? 7b. What is pH? What is the pH of natural rain water? Of ``acid rain"? What is the range of pH that freshwater fish and amphibians can tolerate? What kind of bedrock makes ecosystems less sensitive to acid rain? What can be used to buffer a lake? How do acid rain and ozone act together to damage forests? 8. What causes high ozone concentrations over the South Atlantic in September? 9. What is Daisy World and what are its competetive and cooperative aspects? How might phytoplankton regulate the amount of tropical clouds? What is the temperature range for healthy coral growth? What is coral bleaching? Why might hurricanes be more frequent and powerful in an enhanced greenhouse gas scenario? 10. What are a reservoir, source, sink, and flux? What is a cycle? What leads to a trend? What might make it difficult to diagnose a trend? For earth system cycles, each component is interdependent, with many feedbacks. What are some of the ways that we are reducing the complexity of this feedback system? How might this affect the stability of the system? 11. List a unit commonly used to describe the global carbon budget. What is the current reservoir of atmospheric carbon and its current rate of increase? How big is the fossil fuel reservoir compared to the atmosphere, land biosphere, and ocean reservoirs? What are the main natural sources and sinks for atmospheric CO$_2$? What are the main anthropogenic sources of atmospheric CO$_2$? What is the ``missing sink" problem and where might it be? What are some of the uncertainties in the carbon budget? What is the ``biological pump"? What is the residence time of carbon dioxide in the deep ocean? In the IPCC scenarios, what is the range of CO2 concentration expected in the year 2100? 12. What is the boreal forest and what is the primary species in it? What is ``CO$_2$ fertilization"? Why is the rate of plant migration important to global change? What would likely happen to atmospheric carbon dioxide concentrations from warming up soils? 13. What is gene plasm? Who was Nikolai Vavilov? Why would we care about maintaining seed banks? Give two examples illustrating the importance of genetic diversity. 14. About how much rain falls over the globe each year? How long does a water vapor molecule typically reside in the atmosphere? How far will it typically travel? Over continents, rainfall exceeds evaporation. What maintains an equilibrium? What might happen to continental rainfall if plant cover were reduced? What might happen if a river were diverted? 15. What is the ITCZ? What is the Sahel? How could overgrazing lead to an expansion of the Saharan desert? 16. In the U.S., how much water does each of us use each year? What is most of it used for? How many food calories does the average person need? How much heat do we emit? How much land is required to grow a year's worth of food for a vegetarian, compared to a person who gets most of their calories from meat? How much agricultural land per person is available on earth right now? What is net primary productivity? About what percentage of the earth's net primary productivity is used by humans? Given ``business as usual", how many more people could the earth support?