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Unit 9: Global Change: 4.55: Ozone

MigrationUnit 9 overview:

  • module 55 ozone
  • module 56 greenhouse effect
  • module 57 greenhouse gases
  • module 58 ocean warming and acidification
  • module 59 invasive and endangered species, biodiversity
Module 55: Ozone
Bozeman Science:
Two types:
  • stratospheric ozone: protects life by absorbing UV-C rays
  • tropospheric ozone: surface air pollution from industry, transportation
Three types of UV (ultraviolet) radiation:
  • UV-C highest energy, splits DNA
  • UV-B lower energy, damages photosynthesis
  • UV-A lowest energy, can damage DNA

Screen Shot 2023-04-02 at 3.53.40 PM.png
Screen Shot 2023-04-02 at 3.53.40 PM.png

  • Note that UV-C (the most powerful of the ultraviolet rays) is absorbed by the stratospheric ozone layer
  • Formed by UV-C splitting O2 into O + O, then O + O2 = O3 (ozone)
  • This can then be split again into O2 + O by UV-N or UV-C rays, so there is equilibrium
CFC= chlorinated fluorcarbon, can release a single Cl atom
O3 + Cl --> ClO + O2  (note this is transparent to UV)
one Cl atom can do this many thousands of times, depleting the ozone layer

Here's what we saw back in progressthe 1990's over Antarctica:
7d179.png
7d179.png

This "ozone hole" was growing larger, and global ozone was also decreasing:
Screen Shot 2023-04-02 at 4.02.37 PM.png
Screen Shot 2023-04-02 at 4.02.37 PM.png

In 1997, most of the countries of the world met in Montreal Canada to create the Montreal Protocol, banning these CFC’s (chlorinated fluorocarbons) like Freon. replacing them with similar non-harmful refrigerants called HCFCs

Here’s how we know it worked:

https://www.esrl.noaa.gov/gmd/aggi/

Screen Shot 2023-04-02 at 4.06.00 PM.png
Screen Shot 2023-04-02 at 4.06.00 PM.png
This demonstrates that if every country decides to change for the survival of the planet, it can be done.
Why do you think this is different for global warming?

Why does this show up on every AP exam?
How does it demonstrate cause and effect?
How does it demonstrate why solving the climate crisis is different?

Ozone crisis:
Everybody dies, no more food, no international or rich/poor boundaries-EVERYONE DIES
Clear pattern of cause and effect
Visible impact in an area not yet dangerous (ozone hole over Antarctica)
Economical alternatives created (new safer HCFCs instead of CFCs)

Climate crisis: 
Tied to national interests (economy, money, energy, development)
Only poor folks on the coastal areas will be impacted (flooding, malaria, disease, loss of food)
Only some countries' food supply will be impacted (corn in Nebraska is ok, rice in the Mekong delta: salt intrusion)
Rich folks can afford air conditioning and when it becomes severe, CO2 scrubbing indoors (gated community model)
Lots of misinformation created by money interests (oil companies, certain politicians tied to them)
Energy sources are not uniform: lots of coal in China, lots of oil in Arabian gulf
Renewable energy alternatives stifled by inconsistent investment
Lack of clear information about cause and effect.

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