1-9: Ozone Reactions: Physics and Chemistry of the Stratosphere

Pre-Class Preparation

Objectives

To review atmospheric measurements of manmade chemicals and concurrent measurements of stratospheric ozone.
To understand the atmospheric conditions, chemicals, and complex reactions leading to ozone depletion in certain regions of the atmosphere.

Procedure

Read the learning unit.
Class images
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.

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.

	Phasing Out CFCs: The Vienna Convention and Its Montreal Protocol. (From UNEP.)
	Houghton, J. T., G. J. Jenkins, and J. J. Ephraums, 1990: Climate Change, The IPCC Scientific Assessment. Cambridge University Press. p. 27-28.

Class Discussion

Problem to ponder...
If we have too much ozone in the troposphere in large cities and too little in the stratosphere, why can't we just pipe it up from the cities to the lower stratosphere (the level where jet aircraft fly)?
Class Discussion Summary: by classmate Jay Berkey
2/2/98
We continued our discussion of unit 1-9: Ozone reactions. The vital element of this discussion was the idea that CFC´s present a double danger to the global environment: they have the potential for ozone depletion AND they contribute to global warming. More definitively, CFC´s limit ozone production and therefore allow more UV radiation through the atmosphere. But also, CFC´s have high absorbing capabilities at wavelengths between 7 and 10 micrometers-- a wavelength parameter at which the earth radiates with considerable energy. To illustrate this point we viewed a slide from 1-12: Global Energy Balance, which shows the absorption spectra of different substances, including CFC´s, water vapor, carbon dioxide, etc.
We then looked in to the advantages of adding hydrogen to the CFC molecule (HCFC). HCFC´s are more reactive than CFC´s, and therefore are used in the troposphere rather than rising unreacted to the stratosphere.
We briefly touched on the issue of methyl bromide and the controversy surrounding its use and the effort to ban it. Along with this we discussed the idea of a North/South axis where the industrial nations of the northern hemisphere want to regulate methyl bromide, yet less industrialized nations of the southern hemisphere, which rely on methyl bromide agriculturally, have no other other economically viable options. And the northern nations won´t cut them a break, essentially. It´s interesting to note that the U.S. is the chief PRODUCER of methyl bromide in the world.
We then looked at data and figures from Kern and McElroy from their studies in Toronto. Their findings offer convincing evidence that the increased UV radiation is occurring where ozone would ordinarily absorb it.
To close the discussion, we tried to end on a positive note. We examined the projections of the Montreal Protocol of 1987 and it´s revisions of ´90 and ´92 and saw what dramatic improvement can be made to re-close the ozone hole if the nations of the world would adopt the provisions of the Montreal Protocol.

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

	Costs and Benefits of the Montreal Protocol
	CIESIN Thematic Guides: Environmental Effects of Ozone Depletion.
	Ozone Depletion. (Global warming and ozone depletion are different but related issues).
	Ozone, What Is It, and Why Do We Care About It?
	UNEP's OzonAction Programme: Creating Enabling Conditions
	Gleason, J.F., et al., 1993: Record Low Global Ozone in 1992. Science, 260, 523-526.
	Hoffmann, D. J., et al., 1992: Observation and Possible Causes of New Ozone Depletion in Antarctica in 1991. Nature 359, 283- 287.
	Houghton, J.T., G.J. Jenkins, J.J. Ephraums, eds, 1990: 1990 Intergovernment Panel on Climate Change, Cambridge University Press, 27-30.
	Kerr, R. A., and C. T. McElroy, 1993: Evidence of Large Upward Trends of Ultraviolet-B Radiation Linked to Ozone Depletion. Science, 262, 1032-1034.
	Kerr, R. A., 1993: Ozone Takes a Nose Dive After the Eruption of Mt. Pinatubo. Science, 260, 490-491.
	Lloyd, Steven A., 1993: Stratospheric Ozone Depletion. The Lancet, 342, 1156-1158.
	Rowland, F. Sherwood. 1990: Stratospheric Ozone Depletion by Chlorofluorocarbons. Ambio, 19, 281-292.
	Tabazadeh, A. and R. P. Turco, 1993: Stratospheric Chlorine Injection by Volcanic Eruptions: HCL Scavenging and Implications for Ozone. Science, 260, 1082-1085.
	Taubes, Gary, 1993: The Ozone Backlash. Science, 260, 1580-1583.
	Zurer, Pamela S., 1993: Ozone Depletions Recurring Surprises Challenge Atmospheric Scientists. C & EN, May 24, 8-18.

References

	Atmospheric Chemistry and Air Quality Glossary
	Observation and Possible Causes of New Ozone Depletion in Antarctica in 1991.
	Ozone Depletion and global environmental change from CIESIN
	Ozone Depletion from the National Academy of Sciences
	Ozone Depletion FAQ Page developed by the University of Utrecht
	Ozone Depletion Glossary
	Ozone Fact Sheet from NASA
	Phase Out of Methyl Bromide.
	Stratospheric Ozone Home Page developed by EPA
	UV-B and Ozone depletion bibliography from NASA, 1994 and 1995-1997, 1994, 1995-1997.
	Bekki, S., K. S. Law and J. A. Pyle. 1994: Effect of Ozone Depletion on Atmospheric CH₄ and CO concentrations. Nature, 371, 595-597.
	Brasseur, G., 1992: Volcanic Aerosols Implicated. Nature, 359, 275-276.
	Kerr, J.B. and McElroy, C.T., 1993: Evidence for Large Upward Trends of Ultraviolet-B Radiation Linked to Ozone Depletion. Science, 262, 1032-1034.
	Kerr, R.A., 1994: Antarctic Ozone Hole Fails to Recover. Science, 266, 217.
	Kerr, R. A. 1996: Ozone Destroying Chlorine Tops Out. Science, 271, 32.
	Kerr Richard A., 1990: Ozone Destruction Closer to Home. Research News, March, 297.
	Posey, Carl A., 1994: Ozone Forecast: Partly Cloudy. Air and Space, November, 28-38.
	Rowland, F. Sherwood, 1990: Stratospheric Ozone Depletion by Chlorofluorocarbons. Ambio, 19, 281-292.
	Wang, W. C., X. Z. Liang, M. P. Dudek, D. Pollard, and S. L. Thompson.: Atmosphere Ozone as a Climate Gas. Atmospheric Research, 37, 247-256.