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Badlands National Park, SD

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Chlorofluorocarbons and the Ozone Layer

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Cast of Characters The stratosphere ~ 15 miles above earths surface UV light Stratospheric clouds Gases in the stratosphere NO x Ozone Chlorine Tropospheric pollutants CFCs Halons

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A Brief History of the Ozone Layer 19th century Stratospheric ozone identified as block for UV 1920s Ozone layer identified Thickness measured Dobson invents ozone spectrophotometer 1924: measurements of ozone layer begin in Arosa 1930s 1st synthesis of CFCs: T. Midgely Low boiling point Nontoxic Not inflammable Applications developed Refrigeration 1950s CFC uses expand rapidly

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Ozone Layer: Continued 1960s SST fleet proposed NO x catalytic destruction of O 3 1970s: fears of O 3 destruction Congress axes funds for SSTs Cl implicated CFCs detected in stratosphere Rowland & Molina warn of CFC role 1977: 1st meeting on O 3 depletion 1978: US bans nonessential CFC aerosols 1985: Vienna Convention 1987: Montreal Protocol 1991: Phase out CFCs by 1996 US, Europe 2000: Maximum CFC in stratosphere 2010: End CFC use worldwide

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1987: measuring ozone

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Ozone Levels In troposphere Limit value: 110 g/m 3 for 8-hour- average concentrations In stratosphere: Over US: ~ 300 DU Over Antarctica: ~ 117 DU Dobson Unit 27x10 6 molecules/cm 3. Winnipeg is about 200 miles south of Edmonton (and considerably to the east)

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New South Wales, Australia Oslo, Norway Stratospheric Ozone Levels: Temporal and Geographic Variation

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http://www.redorbit.com/news/space/1112481470/ozone-suite-on-suomi-npp- continues-more-than-30-years-of-ozone-data/

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http://www.scmp.com Some Recovery of the Ozone Layer Is (Probably) Occurring

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http://theenergycollective.com/jcwinnie/46970/back-ozone-treaty PREDICTED: The Ozone Layer Without Regulation of CFCs

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Trichlorofluoromethane: CFC-11 -- 50 yr residence time Dichlorodifluoroethane: CFC-12 -- 102 year residence time Chlorofluorocarbons

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Bromotrifluoromethane: Halon-1301 -- 65 years Bromochlorodifluoromethane: Halon-1211 -- Carbon tetrachloride: Halon 10 -- 42 years Methyl bromide: 0.7 years Methyl chloride Dichloromethane (Methylene chloride) Related Compounds

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http://jan.ucc.nau.edu/~doetqp-p/courses/env440/env440_2/lectures/lec41/lec41.htm

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Major Uses of CFCs http://mad4science.wordpress.com/

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. And the Interaction

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http://www.esrl.noaa.gov/gmd/hats/publictn/elkins/cfcs.html CFCs in the Atmosphere: 1977-1995

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Remember The Time Line 1930s 1st synthesis of CFCs by T. Midgely Low boiling point; nontoxic; not inflammable Application: Refrigeration 1950s CFC uses expand rapidly 1970s: fears of O 3 destruction Congress axes funds for SSTs Cl implicated CFCs detected in stratosphere Rowland & Molina warn of CFC role By 2010, CFC production was officially ended worldwide. How did this happen?

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Repairing the Ozone Layer: International Action 1976: 1st UNEP meeting 1985 Vienna Convention Intergovernmental Cooperation Exchange of information Systematic observation of O 3 Monitoring of CFC production Framework agreement No controls or targets 1987 Montreal Protocol adopted Phase-out schedule for regulated chemicals Method for modifying agreement Leeway for developing countries Chemicals Regulated Halocarbons CFCs HCFCs Temporary replacements for CFCs HBFCs To prevent increasing use HFCs to be phased out?? Methyl bromide Carbon tetrachloride Methyl chloroform

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Consumption of chlorofluorocarbons (tonnes of ozone depleting potential) by region and global, 19882002

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Top: CFC Production 1969-2003 Bottom: HFC production 1989-2003 http://www.unep.org/ yearbook/2004/111.ht m HFCs do not deplete the ozone layer, but they do contribute to climate change.

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International cooperation seems to have solved the ozone layer problem: Can we do it again for climate change? What is the role of the US?

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Badlands National Park, SD