Ozone Depletion Chapter 13-2

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Ozone DepletionChapter 13-2
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Ozone layer

• A layer in the stratosphere that is made of ozone
  (O3)
• Absorbs ultraviolet light from the sun, protects
  organisms from damage to DNA, especially due to
  UVB

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Review The atmospheres four layers
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CFCs

• Chlorofluorocarbons man-made chemicals that
  were used in aerosol propellants, air
  conditioners, refrigerants

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How CFCs break down ozone
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How CFCs break down ozone

• Free chlorine atoms break O3 apart when UV light
  strikes CFC molecules, creating ClO and O2
• Cl O3 ? ClO O2
• Chlorine breaks away from ClO and can then break
  apart another O3 molecule, continues over and
  over
• One CFC molecule can break down 100,000 ozone
  molecules

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Antarctic Ozone Hole
More accurately, a thinning of the ozone layer
every spring over the poles, especially
Antarctica Why? The very cold climate and clouds
that form in winter lead to more ozone depletion
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Ozone Hole

• The ozone layer over the Arctic is also thinning
  for the same reasons.

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Effects of Ozone Layer Depletion

• Human Health
• Worse sunburn
• More eye cataracts
• More skin cancers
• Immune system suppression

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Ultraviolet A
Ultraviolet B
Thin layer of dead cells
Hair
Epidermis
Squamous cells
Basal layer
Sweat gland
Melanocyte cells
Dermis
Basal cell
Blood vessels
Squamous Cell Carcinoma
Basal Cell Carcinoma
Melanoma
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Skin Cancers
Melanoma most serious form of skin cancer
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Effects of Ozone Layer Depletion

• Wildlife
• Increased eye cataracts in some species
• Decreased population of aquatic species
  sensitive to UV radiation
• Reduced population of surface phytoplankton
• Disrupted aquatic food webs from reduced
  phytoplankton

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Effects of Ozone Layer Depletion

• Effects on plants
• Reduced yields for some crops
• Decreased forest productivity for UV-sensitive
  tree species

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Effects of Ozone Layer Depletion

• Air Pollution and Materials
• Increased photochemical smog
• Degradation of outdoor paints and plastics
• Acceleration of Global Warming
• Because of decreased ocean uptake of CO2 from
  atmosphere by phytoplankton (means more CO2 in
  atmosphere)
• CFCs are greenhouse gases

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Summary of Effects
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Montreal Protocol

• International agreement to reduce use of CFCs,
  1987
• One of the most successful environmental efforts
  ever
• If countries stop producing ozone-depleting
  chemicals, ozone layer should return to normal by
  2050