Ozone Depletion Lecture Notes Difficult Decisions Series - Science 8 PCDS         credits for this information Tour of the Ozone Hole from Cambridge University Ozone Science Fact Sheet from the EPA Reports to the Nation on Our changing planet : Our Ozone Shield: NOAA TOMS images http://jwocky.gsfc.nasa.gov/

The planet Earth is unique in many aspects. One unique aspect is our atmospheric blanket of Ozone. This layer protects us from harmful radiation while allowing in beneficial rays. First recognized in the early 1970's, Ozone depletion threatens all life on our Planet.

In this lesson students will begin by viewing the 20 minute video "assault on the ozone layer". Following this introduction to the topic students will learn about the topics outlined below. To accomplish this learning students will read articles on the web and in print. To fully appreciate the science that lead to the ozone depletion confirmation, students will measure ozone layer thickness with NIH image's lesson "where did the ozone go ?". As a concluding activity, students will debate the pro's and con's of limiting the use of Ozone depleting chemicals worldwide.

I. Definition of ozone depletion

II. Is Ozone depletion really occurring? how can we find out for sure?

• atmospheric balloons
• natural fluctuations - three theories
  • solar cycle
  • stratospheric winds
  • human chemicals
• computer modeling

III. Arizona Bear's Antarctic Adventure. A simple powerpoint that tells the story

I. The Ozone Layer

• what is ozone ?
• how is it produced?
• what does it do for us ?
• where is it ?
• is it naturally variable ?

II. Ozone Depletion

• what are CFC's and the other chemicals that harm the Ozone ?
• what do they do to harm the ozone layer ?
• why are they in the stratosphere and how do they break down ?
• aren't there natural sources of these gases that are just as harmful ?
• where is the ozone depletion the most noticeable?
• why should we care ?

III. The World's Reaction

• what was the first reaction to the evidence of ozone thinning?
• did the use of CFC's stop immediately? why not?
• what were the Vienna convention and Montreal protocol?
• if these agreements work what should happen to the ozone layer in the future?

IV. The EPA Stratospheric Protection Program

• what has the EPA done about Ozone depletion?
• Under the Clean Air Act, EPA has created several regulatory programs to address numerous issues including:

  • ending the production of ozone-depleting substances
  • ensuring that refrigerants and halon fire extinguishing agents are recycled properly
  • identifying safe and effective alternatives to ozone-depleting substances
  • banning the release of ozone-depleting refrigerants during the service, maintenance, and disposal of air conditioners and other refrigeration equipment
  • requiring that manufacturers label products either containing or made with the most harmful ODS.

• The SunWise School Program

I. The Chemistry behind the depletion

http://www.epa.gov/ozone/science/process.html

D. Myths and Realities

Myth # 1 CFCs are Heavier Than Air, So They Can't Reach the Ozone Layer

Myth # 2 Ozone Depletion Occurs Only In Antarctica

Ozone loss was first noticed in the Antarctic, but has now been traced globally even in North America and the Arctic.

the Ozone Hole tour from Cambridge University

The Recipe For Ozone Loss in Antarctica

• The polar winter leads to the formation of the polar vortex which isolates the air within it.
• Cold temperatures form inside the vortex; cold enough for the formation of Polar Stratospheric Clouds (PSCs). As the vortex air is isolated, the cold temperatures and the PSCs persist.
• Once the PSCs form, heterogeneous reactions take place and convert the inactive chlorine and bromine reservoirs to more active forms of chlorine and bromine.
• No ozone loss occurs until sunlight returns to the air inside the polar vortex and allows the production of active chlorine and initiates the catalytic ozone destruction cycles. Ozone loss is rapid. The ozone hole currently covers a geographic region a little bigger than Antarctica and extends nearly 10 km in altitude in the lower stratosphere.

Ozone depletion Over North America

Myth #3 There are No Links Between Ozone depletion and Higher UV

Myth # 4 Volcanoes and the Oceans are causing ozone depletion

E. Benefits of the CFC Phase out

I. Protection of the Ozone layer

II. Reduced Health Risks

III. New Technologies

IV. Energy Savings

V. Pollution Prevention

F. Costs of the CFC Phase out, and should all countries be required to comply?

I. The costs to the CFC industries

II. Supersonic transport damages the Ozone, but is an efficient way to travel the globe.

III. Multi dose Inhalers - needed by asthmatics and others with Cardiopulmonary diseases.

IV. Halons make the best fire extinguishers

V. Not every country can afford the new replacement chemicals

VI. Are we sure the new safer chemicals don't have impacts of there own?