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The ozone layer is found in the stratosphere The ozone layer is in the stratosphere Good up high! Bad nearby! ◦ It protects the Earth from ultraviolet rays emitted by the sun. ◦ The wavelengths of ultraviolet radiation are absorbed by the ozone molecules. Ozone absorbs uv-b radiation There is a natural cycle of formation and depletion of ozone The depletion of the ozone layer has been big news since the 1980’s Sherwood Rowland, Mario Molina, Paul Crutzen– 1995 Nobel Prize Winners for Atmospheric chemistry “What’s the use of having developed a science well enough to make predictions if, in the end, all we’re willing to do is stand around and wait for them to come true?” - Rowland Chlorofluoro carbons (CFC’s) and other halogenated hydrocarbons contribute to the destruction of stratospheric ozone. Just one chlorine and bromine atom can catalyze the destruction of 100,000 ozone molecules CFC’s (chlorofluorocarbons) Other harmful compounds include HCFCs, halons, methyl bromide, carbon tetrachloride, NO2, and methyl chloroform. CFCs were used in refrigerators, home insulation, aerosols, plastic foam, and throwaway food containers. Note: Both chlorine and bromine from halogenated hydrocarbons deplete the ozone. Chlorine and bromine-containing compounds (CFC’s) are stable in the troposphere, but degraded under intense ultraviolet light in stratosphere. UV rays release the chlorine (Cl) from the CFCs, causing ozone (O3) to be depleted The chlorine and bromine atoms catalyze the destruction of stratospheric ozone. The “ozone hole” is a seasonal decrease in stratospheric ozone at the polar regions during spring A polar vortex isolates the stratosphere above the poles in the arctic and antarctic winters. The CFC’s are concentrated in this vortex. The chlorine atoms break off the CFC’s in the spring when the sun hits them. Research.. Measurements of the ozone above Antarctica A comparison of arctic and Antarctic ozone Is this showing the ozone over Antarctica or the Arctic? Linked to skin cancer – a deadly cancer Linked to cataracts on the lens of the eye causing blindness Uv light changes DNA in the skin, this can cause tumors, and can lead to cancer UV light and skin cancers Melanoma Cataracts Disruption of plant cycles and food chains ◦ May limit plant growth and change plant form, how nutrients are distributed, Lowers levels of surface phytoplankton in the ocean Damages the base of the ocean food chain Productivity of phytoplankton Research Limiting the use of CFC’s is difficult Ban the production and use of CFC’s Use CFC substitutes such as HCFC’s and HFC’s Recycling refrigerants Alternatives to gas-blown plastics Alternative propellants Alternatives to methyl bromide, a fungicide Montreal Protocol (1987): 30 countries agreed to reduce CFC, also encouraging other countries. ◦ Effectiveness: As a result of the Protocol, ozone- depleting gases have been reduced in recent years. Expected to be completely reduced by 2050. ◦ Countries are required to report annually on their consumption and emission of ozone depleting substances to the UNEP London Convention (1990) Copenhagen (1992) http://www.nasa.gov/centers/jpl/images/content/156227main_ozone- 20060830-graph-browse.jpg Without the Montreal Protocol, skin cancers would have been much worse It will take time for the ozone layer to recover. "Data Reporting and Access." The Ozone Secretariat - Home. 05 Mar. 2009 <http://ozone.unep.org/Data_Reporting/>. "Data Reporting and Access. " The Ozone Secretariat – Home”. 05 Mar. 2009 <http://ozone.unep.org/Data_Reporting/>. NOAA Earth System Research Laboratory. 05 Mar. 2009 <http://www.esrl.noaa.gov/csd/assessments/2002/qandas16.pdf>. "Ozone Depletion - Causes." Oracle ThinkQuest Library. 05 Mar. 2009 <http://library.thinkquest.org/26026/Environmental_Problems/ozone_depletion_ -_causes.html>. "Ozone Depletion - Effects." Oracle ThinkQuest Library. 05 Mar. 2009 <http://library.thinkquest.org/26026/Environmental_Problems/ozone_depletion_ -_effects.html>. "The Ozone Depletion Pheno... - The Problem." 05 Mar. 2009 <http://www.beyonddiscovery.org/content/view.page.asp?I=77>. "Science - Ozone Depletion." NOAA Stratospheric Ozone Webpage. 05 Mar. 2009 <http://www.ozonelayer.noaa.gov/science/o3depletion.htm>. "UNEP Environmental Effects of Ozone Depletion: Executive Summary." Socioeconomic Data and Applications Center. 05 Mar. 2009 <http://sedac.ciesin.org/ozone/docs/UNEPsummary96.html>.
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