"the antarctic ozone hole"
DESCRIPTION
"The Antarctic Ozone Hole". Early concerns about ozone depletion. History of Ozone Depletion. CFCs developed in 40’s and 50’s Refrigerants, propellants, fire retardants 1970’s CFCs detected in atmosphere. Many of these have long atmospheric lifetimes (10’s to 100’s of years) - PowerPoint PPT PresentationTRANSCRIPT
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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.