1. Ozone Depletion

• Ultraviolet radiation from the Sun creates the protective ozone layer in our atmosphere, and the amount of ozone it produces varies over the 11-year cycle of solar magnetic activity.
  
  
• Synthetic chemicals called chloroflurocarbons, or CFCs for short, have been destroying the thin layer of ozone that protects human beings from dangerous solar ultraviolet radiation.
  
  
• The production of ozone-destroying chemicals has been outlawed by an international agreement named the Montreal Protocol.

Copyright 2009, Professor Kenneth R. Lang, Tufts University