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 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: Food & forests: Wildlife:
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
If nations follow, could return to pre-1980 levels by 2068
O3 can naturally
replenish itself