Transcript Global Change: Ozone Depletion

Global Change:
Ozone Depletion
Environmental Sustainability Educational Resources
prepared by
Gregory A. Keoleian
Associate Research Scientist,
School of Natural Resources and Environment
Co-Director, Center for Sustainable Systems
University of Michigan
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Contents
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Ozone Depletion Process
Ozone Hole
Ozone Hole
Ozone Depleting Substances
Ozone Depleting Substances
Ozone Depleting Substances
Ozone Depletion Potential
Ozone Depletion Potential
Impacts
[slide 4]
[slide 5]
[slide 6]
[slide 7]
[slide 8]
[slide 9]
[slide 10]
[slide 11]
[slide 12]
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• Montreal Protocol
• Additional Resources
[slide 13]
[slide 14]
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Ozone Depleting Substances
• Chlorofluorocarbons (CFC’s)
– contains: Cl, F, C
– long-lived, non-toxic, non-corrosive, and nonflammable
– in 1960’s used in refrigerators, air conditioners,
spray cans, solvents, foams
– phase out by 1996 in developed countries
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• Hydrochlorofluorocarbons (HCFCs)
– contains: H, Cl, F, C
– first major replacement for CFC
• ODP’s range from 0.01 - 0.1
– much less destructive by also ozone depleting
– reduce HCFC’s by 35% by 2004 in developed
countries
• Hydrofuluorocarbons (HFC)
– contain: H, F, C
– do not deplete O3
– some HFC’s have a high GWP
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• Halons
– contain: Br, Cl (in some but not all), F, H (in
some but not all), C
– Br many times more effective in destroying O3
• ODPs range up to 10
– used in fire extinguishers
– phase out by 1994
• Methyl Bromide (CH3Br)
– an effective pesticide, used to fumigate ag soil
and products
– ODP = 0.4
– production in US will end 12/31/2000
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Ozone Depletion Potential
• Ozone Depletion Potential (ODP): a number
that refers to the amount of ozone depletion
caused by a substance
• The ODP is the ratio of the impact on ozone
of a chemical compared to the impact of a
similar mass of CFC-11.
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Ozone Depletion Potential
• ODP of CFC-11 is defined to be 1.0.
• Other CFCs and HCFCs have ODPs that
range from 0.01 to 1.0.
• Halons have ODPs ranging up to 10.
• Carbon tetrachloride has an ODP of 1.2
• Methyl chloroform's ODP is 0.11.
• HFCs have zero ODP because they do not
contain chlorine.
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Impacts
• Ozone layer absorbs most of the harmful
UV-B radiation; more UV-B means:
– more melanoma and non-melanoma skin
cancers
– more eye cataracts
– weakened immune systems
– reduced plant yields
– damage to ocean eco-ecosystems
– more damage to plastics
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Montreal Protocol
• Vienna Convention in 1985
– framework agreement
• Montreal Protocol in 1987
– Phase-out schedules for CFCs and halons
• London Amendment in 1990
– accelerated phase outs; additional CFC’s, CCl4, CH3CCl3
• Copenhagen Amendment in 1992
– added methyl bromide, HBFCs, HCFCs
• Montreal Amendment in 1997
– finalized phase-out schedules for methyl bromide
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Additional Resources
• US EPA
– web site: http://www.epa.gov/ozone/
• NASA
– web site:
http://www.nas.nasa.gov/Services/Education/R
esources/TeacherWork/Ozone/Ozone.homepag
e.html
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