The Ozone Shield Our clear guardian

What are we supposed to be learning? SEV3. Students will describe stability and change in ecosystems.  Describe interconnections between abiotic and biotic factors, including normal cyclic fluctuations and changes associated with climatic change (i.e. ice ages). SEV5 e. Describe the effects and potential implications of pollution and resource depletion on the environment at the local and global levels (e.g. air and water pollution, solid waste disposal, depletion of the stratospheric ozone, global warming, and land uses).

Some Key Words Go to your Vocabulary sheet and quickly fill out the know, seen and no idea section for the following words.  Ozone Layer  Chloroflorocarbons (CFCs  Ozone Hole  Polar Stratospheric clouds

What are you getting out of this? Why is the threat to the ozone layer still continuing? Explain how chlorofluorocarbons damage the ozone layer.

Ozone? The Ozone layer –Section of the stratosphere where O 3 is highly concentrated –Absorb most UV from the sun UV damages genetic info  Acts as our plants sunscreen

What is harming O 3 ? Chloroflorocarbons (CFC) –Do not react at the Earth’s Surface So thought were not harmful and were used everywhere in the 1970 and most of the 1980s  In the stratosphere Absorbs energy from UV which breaks the CFCs apart The Cl is released and takes an O from the O 3. The ClO then breaks another O 3 molecule releasing the Cl, and the cycle starts over again. Estimated that 1 Cl can destroy 100,000 O 3 molecules

Oops… We’ve got a hole A thinning of the stratospheric ozone that occurs over the poles during the spring  The ozone layer above Antarctica started thinning in 1979, but not discovered until %-98% thinner than should be  Also decreasing in the Artic

This shows the thickness of the Earth's ozone layer on January 27th from 1982 to This atmospheric layer protects Earth from dangerous levels of solar ultraviolet radiation. The thickness is measured in Dobson units, in this image, smaller amounts of overhead ozone are shown in blue, while larger amounts are shown in orange and yellow. These ozone measurements begin with the Nimbus 7 satellite; continue with the Earth Probe Total Ozone Mapping Spectrometer (EP TOMS); the Ozone Monitoring Instrument (OMI) aboard the Aura satellite; and the most recent, the Ozone Mapper Profiler Suite (OMPS) aboard the satellite Suomi National Polar-orbiting Partnership (NPP). Suomi NPP is a partnership between NASA, NOAA and the Department of Defense. Credit: NASA/NOAA

How did it happen? Polar stratospheric clouds  formed during winter by the polar vortex  Composed of water and nitric acid –Cl 2 is formed on them from CFCs Spring returning  Sunlight comes and splits the Cl 2 into Cl –Roughly 70% can be destroyed in the spring  Causes thinning

Can we transfer it? Ground level ozone  We call it smog Unfortunately, O 3 is very chemically reactive and will not make through the troposphere to reach the stratosphere  And we do not have the technology to pump it up there.

What is the affect of the thinning? More UV passes through since we are using a lower SPF –Damages DNA causing mutation Susceptible to skin cancer  Kill off phytoplankton Disrupts aquatic food chains  Interfere with photosynthesis  Kill egg of amphibians

So, what can we do? Montreal Protocol  1987: Limits the amount of CFCs produced Copenhagen, Denmark  1992: eliminate most CFCs by 1995  USA ban all harmful substances by 2000 Will remain active in the stratosphere for yrs.