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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

"The Antarctic Ozone Hole"

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Early concerns about ozone Early concerns about ozone depletion depletion

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

History of Ozone DepletionHistory of Ozone Depletion

CFCs developed in 40’s and 50’sCFCs developed in 40’s and 50’s– Refrigerants, propellants, fire retardantsRefrigerants, propellants, fire retardants

1970’s CFCs detected in atmosphere.1970’s CFCs detected in atmosphere.– Many of these have long atmospheric lifetimes Many of these have long atmospheric lifetimes

(10’s to 100’s of years)(10’s to 100’s of years) 1974 Rowland and Molina propose that CFC’s can 1974 Rowland and Molina propose that CFC’s can

destroy ozone in the stratosphere.destroy ozone in the stratosphere.– CFCs broken apart by UV radiation forming CFCs broken apart by UV radiation forming

chlorine which can destroy ozone quickly:chlorine which can destroy ozone quickly: O3 +Cl ClO+ O2 (Catalytic Reaction)

ClO+O Cl+O2

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Action on CFCs

Rowland and Molina presented findings to Congress

1987 NOZE expedition to Antarctica gathered data which motivated most countries to act

Media covered it in the late 80s and most people were well informed

Consumers acted on information and made purchasing choices based on it

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

History of ozone depletion

1970’s Supersonic Aircraft fleet under review. 1978: CFCs used in aerosols banned. 1985: British Antarctic Survey reports 40% loss of

ozone over Antarctica during spring. (NASA confirms) 1987: Signing of the Montreal Protocol

– International agreement to reduce CFC use– Later agreements agreed to completely phase out

CFC and halons. 1996 Complete ban on industrial production of CFCs

goes into effect.

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

The Ozone Hole

First discovered in 1985: observations from Antarctica extend back into 1950’s.

Characterized as a rapid depletion of ozone over Antarctica during spring.– Ozone hole season, Spring (August – October)– Ozone hole located over mainly over Antarctica.– Ozone hole recovers by late December

Ozone hole caused by human chemicals (CFC’s) Ozone hole not present in early 1970’s

Chlorine gas

Cold TemperaturesT~-80C

Polar Stratospheric

Clouds

Ozone destroying chemicals

Everywhere in

Atmosphere

Sunlight

Ozone Hole

produces

and

and

produces

Ozone Hole Formation

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Total Ozone: October 14, Total Ozone: October 14, 1997 1997

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Satellite Total Ozone from Satellite Total Ozone from 70’s and 90’s 70’s and 90’s

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Is the ozone hole getting Is the ozone hole getting worse? worse?

Montreal Protocol

Based on precautionary principle Scientists were still determining which chemicals

had a strong effect Timeframe – a) CFCs phased out completely in 10 years b) Other ozone depleting chemicals phased out

over longer specific timeframes

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Montreal Protocol

Countries that can’t afford it were helped with Multilateral Fund.

All future decisions based on current scientific findings

Out of 195 countries, 191 signed

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Biggest factors? 17

Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

You Tell Me!

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Ozone depletion module prepared by Eugene C. CorderoOzone depletion module prepared by Eugene C. Cordero

Summary

The Ozone hole develops during spring over Antarctica.

The Ozone hole is produced by unique combination of weather (cold temps) and chemistry (chlorine).

Global ozone trends are negative except in the tropics.