Self-study
The following passage was written in the mid-1990s.
P1
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Intro topic ·
Evidence that earth's atmosphere is warming unusually fast
Warmed about .5 degree Celsius over the last 100 years. This is unprecedented in the previous 1,000 years.
Hypothesis ·
Global warming is connected to the greenhouse effect
Elevated levels of certain gases can trap heat in the atmosphere. Some think this is one cause of global warming.
P2
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Challenge to hypothesis ·
Expected temperature increase from greenhouse effect is higher than actual increase
Opponents of the greenhouse effect connection to global warming used this data to question the theory.
New evidence that fixes problems with old ·
Actual temperatures now match expected temperatures, after accounting for sulfates
Sulfates can lead to cooler temperatures by reflecting energy back into space. After we account for this, models of the greenhouse effect match actual temperatures.
P3
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Another challenge to hypothesis ·
Warming might be due to variations in solar energy
Some scientific models show strong correspondence between solar activity and atmospheric temperature changes.
Challenge fails ·
Solar activity models can't explain entire recent rise in temperature
Average atmospheric temperature fluctuates over long term, but used to be very stable. The solar activity corresponds to those fluctuations. But the recent increase in temperature goes beyond the most extreme fluctuations; these don't fit the model.
Conclusion ·
Greenhouse effect is best explanation for global warming
Passage Style
Critique or debate
Phenomenon-hypothesis (RC)
2.
Which one of the following ████ ██████████ █████████ ███ ████████ ███████ ███ █████████████ ██ ███ ██████ █████████ ███ ████ ██ ███ █████ ██████████
a
Two complementary theories ████ ███ ██████ ████████ ██ ███ ██████ █████████ ███ ████ ██████████ ██ ███ █████ ██████████ █████ ███ █████ ██████ ██ ██████████ ████████ ██ █████ ██ ███ ███████
The author doesn’t compare two theories in P2. The author discusses the greenhouse theory and some evidence that was inconsistent with early models of the greenhouse effect. No other theory is discussed or compared to the greenhouse in theory in P2. (The solar fluctuation theory is discussed in P3.)
b
A theory that ███ ██████ █████ ██ ██ ███████████ ██ ███ ██████ █████████ ██ ███████████ ████████ ██ ███ █████ █████████ ██ █████ ██ ██████████ ████████ ████ ████ ███████ ██ ███ ███████
The author doesn’t reject the greenhouse theory. Nor does the author show greenhouse theory to be problematic in P2. Rather, the author shows how greenhouse theory is still plausible despite initially inconsistent evidence in P2.
c
A theory that ███ ██████ █████████ ██ ███ ██████ █████████ ██ ███████████ ████████ █████ ████████ ██████████ ██████████████ ██ ███ █████ ██████████
This best captures the relationship. The author discusses the greenhouse theory in P2. Then, after considering and rejecting the solar-fluctuation theory in P3 (”weighing additional considerations”), the author tentatively accepts the greenhouse theory. “Tentatively” is acceptable as a description because the author doesn’t say that the greenhouse theory is definitely correct. He merely says that it’s the “best” explanation.
d
A theory that ███ ██████ ████████ ███ ███████ ██ ███ ██████ █████████ ██ █████████████ ███████ ██ ███ █████ █████████ ██ ████████ ██ ███ █████████
The author doesn’t “substantially revise” the greenhouse theory in P3. Rather, the author rejects an alternative theory in P3 and accepts the greenhouse theory as it is described earlier in the passage.
e
A theory whose ████████ ██ ██████████ ██ ███ ██████ ██ ███ ██████ █████████ ██ █████ ██ ███ █████ █████████ ██ ██ ██████████ ████ ████████ █████
The author does not question the validity of the greenhouse theory in P2. Although the author does acknowledge that early models of the greenhouse effect were inconsistent with observed data, and that