S1N3 -20 Feb Lesson Updates

WHAT'S COVERED TODAY....

OZONE DEPLETION 

Video 2 on Ozone Depletion 

• WHAT is Ozone Depletion?

• CAUSES of Ozone Depletion

• EXTENT of Ozone Depletion

• CONSEQUENCES of Ozone Depletion

• MEASURES taken to protect the Ozone Layer / prevent Ozone Depletion

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WHAT is Ozone Depletion?  

• The gradual destruction of the Ozone Layer.                                                           What is Ozone Layer? (a shield around the Earth, protecting life on Earth from the harmful ultraviolet(UV) rays of the Sun.

CAUSES of Ozone Depletion

• CFCs - Chlorofluorocarbons are the main cause of Ozone Delpetion

•  the chlorine contained in the CFCs are destroying the Ozone molecules in the ozone layer
• Found in the cooling agents of refrigerators and air-conditioners, some aerosol sprays and Styrofoam packaging

EXTENT of Ozone Depletion

• Overall thinning of the Ozone layer throughout the world, except at the Tropics (above Tropical Zone). 
• Ozone Depletion is greater over the higher latitudes
• Countries such as New Zealand and Australia reported Ozone losses up to 30 percent
• Over the poles the losses are over 50 percent.

CONSEQUENCES of Ozone Depletion

• Plants are affected by the increase in ultraviolet radiation that damages the plant tissues. This destroys crops resulting in drastic decline in food supply.

Plankton

• Animals are affected as their food chain gets affected.                                                         Plankton (food for many animals in seas and oceans) are killed by too much of UV. This causes the other animals which feed on Plankton to be short of food that leads to a reduction of those species. So the other predators of these species gets affected and it goes on.  

• People are affected as the increased ultraviolet radiation cause health issues such as
• skin cancer, 
• eye disorder such as cataract (causes blurred version and if not treated it can lead to blindness) and 
• weak immune systems making people less resistant to diseases. 

MEASURES

• Individual Effort
• Avoid buying products containing CFCs
• Proper disposal of refrigerators and air-conditioners with licensed agents. 

• National Effort
• Reducing Use of CFCs

• To ban the use of CFCs
• New alternatives developed to replace CFCs in cooling agents in refrigerators and air-conditioners. (Eg. In Singapore, since 1995 all new cars imported in are required by law to be equipped with CFC-free air-conditioning systems)

• International Effort: 
• Montreal Protocol 
• A treaty signed by group of countries to limit the production and use of CFCs.

Do these Questions! (Hand in tmr!) 

1) Describe the International efforts used to reduce Global Warming. 

2) "Individual efforts are most important." Do you agree and Why.