GLOBAL CHANGE OZONE DEPLETION 1 CONTENTS Ozone Depletion

GLOBAL CHANGE: OZONE DEPLETION 1

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

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

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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 7

• 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 O 3 • some HFC’s have a high GWP 8

• Halons • contain: Br, Cl (in some but not all), F, H (in some but not all), C • Br many times more effective in destroying O 3 • ODPs range up to 10 • used in fire extinguishers • phase out by 1994 • Methyl Bromide (CH 3 Br) • an effective pesticide, used to fumigate ag soil and products • ODP = 0. 4 • production in US will end 12/31/2000 9

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. 10

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. 11

IMPACTS • Ozone layer absorbs most of the harmful UVB 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 12

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, CCl 4, CH 3 CCl 3 • Copenhagen Amendment in 1992 • added methyl bromide, HBFCs, HCFCs • Montreal Amendment in 1997 • finalized phase-out schedules for methyl bromide 13

ADDITIONAL RESOURCES • US EPA • web site: http: //www. epa. gov/ozone/ • NASA • web site: http: //www. nasa. gov/Services/Education/Resources/Te acher. Work/Ozone. homepage. html 14