Unit 20 – Unit 20 – Ozone Ozone
DepletionDepletion
Watch the video and answer the question1. How serious is Ozone depletion?2. What causes Ozone depletion?
http://www.youtube.com/watch?v=YRh3yH7Hnew
A nt ar c t ica
A r ct ic
E x t ent
CF Cs
Causes
H uman healt h
M ar ine f ood c hain
Plant gr owt h
D amage mat er ials
Glob al Cl imat e
Consequenc es
I nt er nat ional
N at ional
I nd ivid ual
M easur es
O zone Deplet ion
Text pg 172
Destruction of Ozone (oxygen atoms) in the stratosphere (layer in atmosphere) caused mainly by release of CFCs
Ozone DepletionDefinition
Important!
Troposphere
Stratosphere
Refer to text pg 166
Act as a shield, Protection from harmful Ultraviolet rays from the sun
Characteristics of Ozone layer
• contains ozone gas
• able to REPLACE ITSELF as Ozone gas is continually created in atmosphere (Same as how Oxygen replaces itself)
•However CFC destroys the Ozone gas faster than its replacement
WHOS THE CULPRIT?
1. Look at Text page 167
2. Write down the 4 CAUSES of Ozone depletion on your worksheet now.
Extent – How serious is the problem?
1.Arctic (North pole) – Thinning of the ozone layer + small hole
2.Antarctica (South pole) – Bigger and deeper hole in the ozone layerWhich is more serious?
Consequences of Ozone depletion
Human Health
Skin cancer, cataracts, Weakens immune system
Marine Food Chain
UV kills plankton (marine food)
Affects food chain
Global Climate
Increase global warming due to Increase UV (less plankton = > CO2)
Damage materials
UV radiation deteriorate materials eg Plastics, PVC
Affect Plant Growth & Reduce Crop production (UV stump growth)
Important text pg 169
3 9 c ount r ies
I nt er nat ional
S ingapor e
N at ional
Y ou and me
I nd ivid ual
M easur es
O zone
Deplet ion
Measures(1) International level Montreal protocol signed in 1987 Comprise of 189 countries now To reduce CFC substances
Measures(2) National level Singapore banned use of CFC
products in 1991D Countries can control the import
and manufacture of CFC products
Measures(3) Individual level
You and me Can use CFC free products Educate and encourage others
too
Montreal Protocol
Kyoto Protocol
What is the purpose of it?Which is more effective?
More effective Less effective
Why?
Limit the production and use of CFCs (Ozone depletion)
Reduce emission of greenhouse gas (Global Warming)
Limiting CFC products will not affect economy growth
Limiting GHG = controlling burning of fossil fuel (affects industrialization and economic productivity).