1. 1 Ozone depletion module prepared by Eugene C. Cordero "The Antarctic Ozone Hole"

2. 2 Ozone depletion module prepared by Eugene C. Cordero Early concerns about ozone depletion

3. 3 Ozone depletion module prepared by Eugene C. Cordero History of Ozone Depletion  CFCs developed in 40’s and 50’s –Refrigerants, propellants, fire retardants  1970’s CFCs detected in atmosphere. –Many of these have long atmospheric lifetimes (10’s to 100’s of years)  1974 Rowland and Molina propose that CFC’s can destroy ozone in the stratosphere. –CFCs broken apart by UV radiation forming chlorine which can destroy ozone quickly:  O 3 +Cl  ClO+ O 2 (Catalytic Reaction)  ClO+O  Cl+O 2

4. 4 Ozone depletion module prepared by Eugene C. Cordero

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6. Action on CFCs  Rowland and Molina presented findings to Congress  1987 NOZE expedition to Antarctica gathered data which motivated most countries to act  Media covered it in the late 80s and most people were well informed  Consumers acted on information and made purchasing choices based on it 6 Ozone depletion module prepared by Eugene C. Cordero

7. 7 History of ozone depletion  1970’s Supersonic Aircraft fleet under review.  1978: CFCs used in aerosols banned.  1985: British Antarctic Survey reports 40% loss of ozone over Antarctica during spring. (NASA confirms)  1987: Signing of the Montreal Protocol –International agreement to reduce CFC use –Later agreements agreed to completely phase out CFC and halons.  1996 Complete ban on industrial production of CFCs goes into effect.

8. 8 Ozone depletion module prepared by Eugene C. Cordero The Ozone Hole  First discovered in 1985: observations from Antarctica extend back into 1950’s.  Characterized as a rapid depletion of ozone over Antarctica during spring. –Ozone hole season, Spring (August – October) –Ozone hole located over mainly over Antarctica. –Ozone hole recovers by late December  Ozone hole caused by human chemicals (CFC’s)  Ozone hole not present in early 1970’s

9. Chlorine gas Cold Temperatures T~-80C Polar Stratospheric Clouds Ozone destroying chemicals Everywhere in Atmosphere Sunlight Ozone Hole produces and produces Ozone Hole Formation

10. 10 Ozone depletion module prepared by Eugene C. Cordero

11. 11 Ozone depletion module prepared by Eugene C. Cordero Total Ozone: October 14, 1997

12. 12 Ozone depletion module prepared by Eugene C. Cordero Satellite Total Ozone from 70’s and 90’s

13. 13 Ozone depletion module prepared by Eugene C. Cordero Is the ozone hole getting worse?

14. Montreal Protocol  Based on precautionary principle  Scientists were still determining which chemicals had a strong effect  Timeframe – a) CFCs phased out completely in 10 years b) Other ozone depleting chemicals phased out over longer specific timeframes 14 Ozone depletion module prepared by Eugene C. Cordero

15. Montreal Protocol  Countries that can’t afford it were helped with Multilateral Fund.  All future decisions based on current scientific findings  Out of 195 countries, 191 signed 15 Ozone depletion module prepared by Eugene C. Cordero

16. 16 Ozone depletion module prepared by Eugene C. Cordero

17. Biggest factors? 17 Ozone depletion module prepared by Eugene C. Cordero You Tell Me!

18. 18 Ozone depletion module prepared by Eugene C. Cordero Summary  The Ozone hole develops during spring over Antarctica.  The Ozone hole is produced by unique combination of weather (cold temps) and chemistry (chlorine).  Global ozone trends are negative except in the tropics.