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Global Change: Ozone Depletion

Global Change: Ozone Depletion. Environmental Sustainability Educational Resources prepared by Gregory A. Keoleian Associate Research Scientist, School of Natural Resources and Environment Co-Director , Center for Sustainable Systems University of Michigan. Contents.

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Global Change: Ozone Depletion

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  1. Global Change: Ozone Depletion Environmental Sustainability Educational Resources prepared by Gregory A. Keoleian Associate Research Scientist, School of Natural Resources and Environment Co-Director, Center for Sustainable Systems University of Michigan

  2. Contents • Ozone Depletion Process [slide 4] • Ozone Hole [slide 5] • Ozone Hole [slide 6] • Ozone Depleting Substances [slide 7] • Ozone Depleting Substances [slide 8] • Ozone Depleting Substances [slide 9] • Ozone Depletion Potential [slide 10] • Ozone Depletion Potential [slide 11] • Impacts [slide 12]

  3. Montreal Protocol [slide 13] • Additional Resources [slide 14]

  4. Ozone Depleting Substances • Chlorofluorocarbons (CFC’s) • contains: Cl, F, C • long-lived, non-toxic, non-corrosive, and non-flammable • in 1960’s used in refrigerators, air conditioners, spray cans, solvents, foams • phase out by 1996 in developed countries

  5. Hydrochlorofluorocarbons (HCFCs) • contains: H, Cl, F, C • first major replacement for CFC • ODP’s range from 0.01 - 0.1 • much less destructive by also ozone depleting • reduce HCFC’s by 35% by 2004 in developed countries • Hydrofuluorocarbons (HFC) • contain: H, F, C • do not deplete O3 • some HFC’s have a high GWP

  6. Halons • contain: Br, Cl (in some but not all), F, H (in some but not all), C • Br many times more effective in destroying O3 • ODPs range up to 10 • used in fire extinguishers • phase out by 1994 • Methyl Bromide (CH3Br) • an effective pesticide, used to fumigate ag soil and products • ODP = 0.4 • production in US will end 12/31/2000

  7. Ozone Depletion Potential • Ozone Depletion Potential (ODP): a number that refers to the amount of ozone depletion caused by a substance • The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of CFC-11.

  8. Ozone Depletion Potential • ODP of CFC-11 is defined to be 1.0. • Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. • Halons have ODPs ranging up to 10. • Carbon tetrachloride has an ODP of 1.2 • Methyl chloroform's ODP is 0.11. • HFCs have zero ODP because they do not contain chlorine.

  9. Impacts • Ozone layer absorbs most of the harmful UV-B radiation; more UV-B means: • more melanoma and non-melanoma skin cancers • more eye cataracts • weakened immune systems • reduced plant yields • damage to ocean eco-ecosystems • more damage to plastics

  10. Montreal Protocol • Vienna Convention in 1985 • framework agreement • Montreal Protocol in 1987 • Phase-out schedules for CFCs and halons • London Amendment in 1990 • accelerated phase outs; additional CFC’s, CCl4, CH3CCl3 • Copenhagen Amendment in 1992 • added methyl bromide, HBFCs, HCFCs • Montreal Amendment in 1997 • finalized phase-out schedules for methyl bromide

  11. Additional Resources • US EPA • web site: http://www.epa.gov/ozone/ • NASA • web site: http://www.nas.nasa.gov/Services/Education/Resources/TeacherWork/Ozone/Ozone.homepage.html

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