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  • Ozone Depletion

    Stratospheric ozone UV light Chemical processes Environmental effects Solutions

  • Atmosphere

    Stratospheric ozone 20-30 km altitude 19 mi at equator, 9 mi at the poles 400 ppb

  • Ozone shield

    99% of all UV is absorbed (UVC and most UVB)

    UVA is not affected by ozone

  • Production of ozone

  • Measurement of Ozone

    Dobson units: 1 ppb ozone

    Survey began in 1957 over the Antarctic

    Taken in October, springtime

    1957-1970: 300 DU 150 DU by 1986

  • Ozone and CFCs Molina and Rowland in

    1974 CFCs are stable Long residence in lower

    atmosphere UV radiation breaks down

    CFC and releases Cl Cl reacts with O3 Increase UVB at the

    surface

  • Formation and destruction of ozone

  • Emissions

  • Usage2003

  • Ozone Hole

  • Polar Stratospheric clouds

    Polar winter formation Have polar vortex Isolated air mass Nitrogen oxides held

    in clouds as nitric acid NO3 particles grow

    and fall out Facilitates ozone

    depleting reactions

  • Polar vortex

    In Springtime, sunlightReturnsNo nitrate to form CloNO2

  • Environmental effects UV damage to DNA Skin cancer Cataracts Suppression of immune

    system Ecosystem: Primary producers Food chains Development in aquatic

    larva

  • Managing ozone depletion Montreal protocol, Sept

    1987 Production of CFC elimination

    Economic gap Replacements: HFC and

    HCFC Shorter lifetime, less

    reactive Collection and reuse (no

    venting) Expensive replacements

  • Climate Change Climate Swings Greenhouse gases Evidence Predictions Control

  • Historic Climate shifts

    Milankovitch cycles: shifts in earths orbit and tilt Volcanic activity: Mt. Toba

  • El Nino/Southern Oscillation Trade winds keep warm water

    in W. Pacific. La Nina El Nino: Shift in tropical

    depression Northern Jet stream splits

    changes rainfall patterns Pacific decadal oscillation:

    warm water in northern pacific moves back and forth.

    Cool water in north help Alsaka salmon runs, warm off coast and then switches.

  • Human Activities

    Industrialization CO2 increased 31%, CH4 inc 151%, N2O inc 17% over

    since pre-industrial times. 40% of excess CO2 absorbed by oceans Methane a big problem

  • Evidence of Climate Change Avg global temperature has climbed 0.6oC over last century Arctic sea ice is 40% thinner, Antarctic glaciers are retreating 50m/yr. Alpine glaciers are retreating Ocean acidification Sea level has risen Changes in animal behavior, breeding cycles Storm frequency and intensity are increasing

  • Larsen B ice shelf-- Antarctica

  • ConsequencesArctic sea ice Alpine glaciers

  • PredictionsPredicted warming with doubling ofCO2

    Sugar maple range

  • Controls

  • Reduction of Carbon Emissions

    Burn less fossil fuel: Turn down your thermostat

    Plant Trees for shade and CO2 uptake Insulate your house Replace old appliances Use compact fluorescence light bulbs Use renewable energy