March 13

Lecture Outline - March 13

Preserving the Ozone Layer 

EPA/Weather Channel Films

               The Electromagnetic Spectrum

               Ultraviolet radiation

               Health Effects of UV radiation

the effects of UV-B radiation

Observations About the Atmosphere

• is very shallow relative to the diameter of the earth

• has changed considerably over its 5 billion year history

• trace gases significantly moderate the flow of energy to and from the earth

• affects and is effected by other parts of the earth system

• humanity has evolved to the point it can significantly alter atmospheric processes

Gases Comprising the Atmosphere

• Nitrogen (78.08%)

• Oxygen (20.95%)

• Argon (0.93%)

• Carbon Dioxide (0.03%)

• Others: Neon, Helium, Ozone, Hydrogen, Krypton, and Methane

Ultraviolet Radiation

Stages in Scientific Knowledge of Ozone Depletion Problem 

•   Discovery and measurement of ozone layer

                1830 - Initial Discovery

                1930 - Dobson Spectrophotometer (for measuring ozone in the statosphere)

                1956 - WMO Ozone Network 

• Theory of threat to ozone layer

               1974 - Molina/Rowland  (theory that CFCs deplete ozone layer)   (other ozone depleting chemicals)

                                     Chemistry of Ozone Destruction

• Evidence of stratospheric ozone loss

                1985 - Antarctic ozone hole announced by British Antarctic Survey   (ozone  hole 2006)

                1980s - lesser loss in temperate regions

                1990s - Arctic ozone hole discovered

                Early 1990s - Evidence of increased UV radiation

                1990s - Evidence of health and environmental impacts

II.   International Agreements to Protect the Ozone Layer   

• 1985    Vienna (Framework) Convention on Protecting the Ozone Layer

• 1987    Montreal Protocol on Substances that Deplete the Ozone Layer  (171 countries have ratified as of 2005)

                     CFCs 

                                20% reduction by 1993

                                50% reduction by 1998

                 Halons 

                                 Freeze at 1986 levels by 1992 

• 1990    London Amendments

                 CFCs  -  100% reduction by 2000

                Halons - 100% reduction by 2000

                Carbon tetrachloride phased out by 2000

                 Methyl chloroform phased out by 2010 

Commitment by developed countries  to assist developing countries transition to alternatives to ozone depleting substances

• 1992    Copenhagen Amendments

•         CFCs - 100% reduction by 1996

  •         Halons - 100% phaseout by 1994

  •         HCFCs 

  •                   Freeze at 1989 levels by 1996 

  •                   35% reduction by 2004 

  •                   65% reduction by 2010 

  •                  100% phaseout by 2020

  •       Methyl Bromide 

  •                   Developing Countries limit production at 1991 levels by 1995 

  •  

•    1995    Vienna Adjustments

                Methyl Bromide 

                    Industrialized countries will 

                          reduce by 50% by 2005 

                          completely phase out , with exceptions for "critical agricultural uses" by 2010

                HCFCs - developed countries move up phase-out date from 2030 to 2020, 

• 1997    Montreal Amendment and Adjustments

• 1999    Beijing Adjustments

                                  Summary of Phase-out Schedules 

III.   Impacts of the Montreal Protocol and Amendments  

•  Reductions in the production and use of ozone depleting substances

• Prognosis for recovery of the ozone layer

• Reasons for further concern

Black market in ozone depeleting substances

Continuing use of methyl bromide in agriculture