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Ozone: The HOLE Story

Ozone: The HOLE Story. Stratospheric Ozone. “Good” Ozone (O 3 ) Blocks 95% of ultraviolet (UV) radiation from reaching Earth’s surface Considerable seasonal thinning over Antarctica and Arctic. Satellite Image. What is the cause?. Chloroflourocarbons , aka CFC’s or freons

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Ozone: The HOLE Story

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  1. Ozone: The HOLE Story

  2. Stratospheric Ozone • “Good” Ozone (O3) • Blocks 95% of ultraviolet (UV) radiation from reaching Earth’s surface • Considerable seasonal thinning over Antarctica and Arctic

  3. Satellite Image

  4. What is the cause? • Chloroflourocarbons, aka CFC’s or freons • Unreactive, odorless, nonflammable, nontoxic, noncorrosive, inexpensive = DREAM CHEMICALS • Used as coolants in air conditioners, refrigerants, aerosol spray cans, styrofoam, etc. • Too good to be true?

  5. YES!! • 1974 – Rowland & Molina – CFC’s (along with other ODC’S) destroy ozone! • Called for an immediate ban • Major conclusions: 1. Persistent 2. Take 11-20 years to reach stratosphere 3. Break down under high-energy UV radiation releasing Cl which “attacks” ozone

  6. HOW?

  7. What time of year? • Typically, the “hole” appears in Antarctica during Spring (Sep, Oct. & Nov) • Why? • During long, cold, dark winter – strong winds create ice crystals at high altitudes • Ozone & chlorine containing molecules build up on ice • Sun reappears after a long winter and “liberates” the Cl – begins “attack”

  8. So, what happens then? • Human Health: • Worse sunburns • More eye cataracts • Increased skin cancer • Immune system suppression • Food & forests: • Reduced crop yields • Decreased forest productivity • Wildlife: • Decreased pops. of sensitive species • Reduced phytoplankton (affect food webs)

  9. We can reverse this! • Stop using ODC’s (still lag time) • MONTREAL PROTOCOL (1987) • Cut emissions of CFC’s by 35% b/t 1989-2000 • If nations follow, could return to pre-1980 levels by 2068 • O3 can naturally replenish itself

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