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).