Question

outline a lecture
working with others in a group, take turns slowly reading sections of the following lecture to one another. as the paragraph is being read, outline the main arguments in the space provided
in 1980, a scientist from britain was working in antarctica. he realized something disturbing. the ozone layer in the local atmosphere had depleted by 30%.
the scientist assumed this ozone hole was due to an unexpected weather development. evidence soon indicated that synthetic chemicals were the cause of the depletion. a high level of chlorine was discovered; this chemical destroys ozone. chlorofluorocarbons (cfcs) were found to be the source; these come from aerosols, air - conditioner coolants, and styrofoam. while normally considered safe, these chemicals were found to be destroying ozone in the cold, thin antarctic atmosphere.
the ozone layer thinning occurred 15 - 25 miles above the earth. ozone blocks ultraviolet (uv) rays from the sun. uv rays can cause cancer and other health issues. a drop of 1% could lead to an increase in skin cancer, but there was a 3% drop which will likely lead to a much larger increase in skin cancers.
while countries shifted their practices to phase out cfcs, all of the cfcs that already existed are still out there (in air conditioners, aerosols, etc.). these will continue to cause ozone depletion. we have recorded ozone depletion over the north pole and the arctic hole is expanding toward the united states and europe.
write your outline here.
working in a group
after you have outlined the passage, compare your outline with those of others who took notes on the same passage.

• did you all agree on the main ideas of each passage?
• how do your notes differ from others and what are the similarities?
• how might you improve your notes to better capture the main points?
• would a different topic produce greater or fewer difficulties?

Explanation:

1. In 1980, a British scientist in Antarctica found 30% ozone - layer depletion.
2. Initially thought to be weather - related, but synthetic chemicals (CFCs) from aerosols, etc. were the cause.
3. Ozone layer is 15 - 25 miles above earth, blocks UV rays which can cause health issues like cancer.
4. A 3% drop in ozone may lead to a large increase in skin cancers.
5. Although countries are phasing out CFCs, existing ones still cause ozone depletion and the Arctic hole is expanding.

Answer:

1. Discovery of Antarctic ozone - hole (1980, 30% depletion)
2. Cause: Synthetic chemicals (CFCs)
3. Ozone layer's role and health risks
4. Impact of ozone drop on skin cancer
5. Continued ozone depletion and Arctic hole expansion