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The Ozone Shield

The Ozone Shield. Atmosphere and Climate Change Chapter Thirteen Section Two. The Ozone Shield. Ozone layer – part of stratosphere where ozone is concentrated Absorbs most of the harmful ultraviolet (UV) rays from the sun UV rays damage genetic material

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The Ozone Shield

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  1. The Ozone Shield Atmosphere and Climate Change Chapter Thirteen Section Two

  2. The Ozone Shield • Ozone layer – part of stratosphere where ozone is concentrated • Absorbs most of the harmful ultraviolet (UV) rays from the sun • UV rays damage genetic material • Ozone layer being damaged by chlorofluorocarbons or CFCs

  3. Chlorofluorocarbons • Nonpoisonous, nonflammable, noncorrosive • Used as coolant in freezers and AC, to make plastic, in spray cans & pesticides • Stable at Earth’s surface • In stratosphere, CFCs broken apart by UV rays • Parts of CFC destroys protective ozone layer

  4. The Ozone Hole • Thinning of stratosphere that occurs over the poles in the spring • In 1985, studies showed the ozone layer over the South Pole had thinned by over 50% • Polar stratospheric clouds make air very cold which leads to breakdown of CFC • When sun returns, energy drives destruction of Ozone

  5. Effects of Ozone Thinning • On Humans – As ozone decreases, UV rays reaching Earth increases • UV rays damage DNA in humans • On Animals & Plants – high UV rays can kill phytoplankton, harm amphibians, interfere with photosynthesis

  6. Protecting the Ozone Layer • 1985 Montreal Protocol led to agreement to limit CFCs • In 1995, developed nations pledged to ban CFCs completely • CFC use has dropped dramatically from over 1,000 millions tons per year to less than 200 million tons per year • CFCs stay in stratosphere 60 to 120 years

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