The Ozone Shield The ozone layer is an

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The Ozone Shield The ozone layer is an area in the stratosphere where ozone

The Ozone Shield The ozone layer is an area in the stratosphere where ozone is highly concentrated. It absorbs most of the UV rays from the sun. Ozone – molecule made of 3 oxygen atoms.

Ozone Depletion • Chlorofluorocarbons (CFCs) – human-made chemical once used as: – Coolants in

Ozone Depletion • Chlorofluorocarbons (CFCs) – human-made chemical once used as: – Coolants in refrigeration & air conditioning – Gassy fizz for making plastic foams – Propellant in spray cans • CFCs –break down in the stratosphere and destroy ozone molecules. – A single CFC can destroy 100, 000 ozone molecules. – Remain active in the stratosphere for up to 120 years.

The Ozone Hole • The ozone hole is a thinning of stratospheric ozone that

The Ozone Hole • The ozone hole is a thinning of stratospheric ozone that occurs over the poles during the spring.

Why is the ozone hole over the poles? • It is so cold at

Why is the ozone hole over the poles? • It is so cold at the poles during winter that clouds are able to form in the stratosphere (polar stratospheric clouds). • CFCs travel into the stratosphere on these clouds.

Negative Effects of Ozone Depletion Humans & Land Animals Amphibians Marine Life Land Plants

Negative Effects of Ozone Depletion Humans & Land Animals Amphibians Marine Life Land Plants Skin cancers Premature aging of skin Cataracts Weakened immune system Death of eggs Genetic mutations Reduced Populations Disruption of food chain (death of surface plankton & photosynthesizers) Photosynthesis interference Reduced crop yields

Protecting the Ozone Layer • Montreal Protocol – agreement among nations to limit the

Protecting the Ozone Layer • Montreal Protocol – agreement among nations to limit the production of CFCs. • Developed nations agreed to eliminate CFCs by 1995. – Aerosol cans no longer use CFCs as propellants – Air conditioners and refrigerators are CFC-free