1-14: Global Warming Potential

Pre-Class Preparation

Objectives

• To understand how the combination of radiative activity and lifetime can be used to evaluate the global warming potential of various gases.
• To see how the global warming potential of the atmosphere is related to concentrations of trace gases and human activity.

Procedure

1. Read the learning unit.

   Class images

2. Take the learning unit quiz. Quizzes are available from your portfolio. You may access your portfolio via the list of students participating in this years course, as represented by the icon below.
   
   
3. Additional Required Reading. Although you are not ultimately responsible for content listed in this section, we encourage you to fully explore the links in order to provide a better scope on the upcoming class discussion.

   	The Case for Reducing Greenhouse Gas Emissions Despite Scientific Uncertainty. (From UNEP.)
   	Measuring the "Global Warming Potential" of Greenhouse Gases. (From UNEP.)
   	Slide Presentation: The Greenhouse Effect; Greenhouse Gas (GHG) Emissions, Concentrations, and Sources; Temperature Data; and Projections of Future GHG Emissions.
   	Tax to Combat Global Warming?

Class Discussion

• Problem to ponder...
  Why does burning of tropical rainforest lead to global warming but burning an equivalent amount (mass) of corn stalks does not?

• Class Discussion Summary: by classmates Erna Sanjaya, Jason Alumbaugh, and T.C. Loving

  The global warming potential (GWP) combines the radiative forcing and lifetimes into one index. The GWP is ratio of a function of the radiative forcing and the concentration of a particular gas compared to carbon dioxide. The uncertainties in GWP included:

  • estimation of lifetimes
  • radiative forcing
  • indirect effects (like water vapor from the oxidation of methane)
  • choosing the appropriate time interval

  
  The GWP doesn't take into account the future emissions but the emissions now.

  As far as GWP CO₂ is the most dominant greenhouse gas. CO₂ accounts for 98% of the total mass of greenhouse gases and 61% of the radiative forcing. Methane and CFC-12 are the next most important gases for GWP.

  Because the GWP takes into account the radiative forcing and the lifetimes of greenhouse gases, it allows us to make rational judgments based on science and not emotion.

  We looked at 4 different scenarios based on changes in human activity with respect to greenhouse gases. The scenarios range from the business as usual scenario to one where there would be dramatic changes in our sources of energy. In looking at the chart of the scenarios, the following comments were made:

  Scenario A: By the year 2100 we would see an increase in radiative forcing that would be 100 times the impact of natural variability (due the sun and volcanos)
  

  Scenario B: We would see significant reductions with little impact on our lifestyle
  

  Scenario C: This scenario would offer only a marginal increase in reductions over scenario B
  

  Scenario D: Is this worth the pain and expense?

  The graphical representations of the chart data puts this into perspective.

  In class we talked about how GWP is an important tool for making scientific, rational decisions as to what course of action we take in the future with regard to greenhouse gases.

Post-Class Activities

• Participate in the electronic dialog. Use this forum for:
  • continuing class discussion;
  • posing new questions to students or the instructor;
  • responding to issues/questions raised by students in class/electronic dialog.

  Visitor Access (Visitors are welcome to participate in the dialog. Just click on the icon below)	Student Access (Students must post all dialog from their portfolio. Click on the icon below to access the student list.)

• Recommended Reading Materials

  Houghton, J. T., L. G. Meira Filho, B. A. Callander N. Harris, A. Kattenberg, and K. Maskell, 1996: Climate Change 1995. The Science of Climate Change. Cambridge University Press, 21-26.

• References

  	9th Global Warming International Conference & Expo (GW9)
  	Climate Change Bulletin.
  	Climate Change Information Kit.
  	EIZENSTAT PREPARED TESTIMONY ON KYOTO PROTOCOL
  	Global Warming International Center.
  	Hot Links to Web Sites on Global Warming. (From Northern Environmental Chemistry.)
  	Stabilization of CO2 emissions with allowances for needs of developing countries
  	Tiempo, a Cyberlibrary on Global Warming.