Reading ComprehensionDifficulty: Medium

PT150 S1 P1 Q1 ExplanationThe Greenhouse Effect

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsMain PointScience

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Passage

The following passage was written in

Evidence that the earth’s atmosphere has warmed has become quite compelling, in part because it has been reinforced recently by the development of accurate profiles of average annual temperatures throughout the last 1,000 years. These data, inferred from studies of geological patterns and samples of ice deposits, tree rings, and coral growth elevated levels in the atmosphere of certain gases that prevent heat from radiating back into space.

Early models charting the greenhouse effect were somewhat inconsistent with observed data; they estimated that the increase in the earth’s atmospheric temperature over recent decades should have been higher than the increase observed in actuality, which led opponents to question the validity of the greenhouse theory. But new methods have enabled scientists ice, these scientists have calculated theoretical temperatures for recent decades that are consistent with observed temperatures.

Another question for proponents of the greenhouse theory comes from scientists who have attempted to tie changes in the earth’s atmospheric temperature to variations in solar energy. From observations of cycles in several types of solar phenomena, these scientists have developed models that chart variations in the sun’s heating effects, and the have raised its equilibrium temperature, and that greenhouse gases represent the best explanation of that shift.

What this question is testing

Main Point

Your task

Capture the passage's overall primary point — the claim everything else supports.

Common trap

Answers that are true but too narrow (a single paragraph) or too broad (beyond the passage's scope).

Winning move

Summarize the whole passage in one sentence first, then match it to a choice.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
1.

Which one of the following most accurately states the main point of

Answer choices, explained

  1. Opposite3% picked this

    Though many accept the theory that the greenhouse effect is causing the recent global warming, that theory is somewhat questionable in light of recent

    The main clause here is that "the greenhouse theory is somewhat questionable". Our author's main point in that final sentence is that "the greenhouse theory is our best explanation for the shift in global temperatures".

  2. Wrong Emphasis3% picked this

    Scientific models of the effects of greenhouse gases, modified to incorporate the effects of airborne sulfates, are important because they predict that the earth's

    The main clause of this answer is, Scientific models of greenhouse gases are important. Our author's main point says, A rise in greenhouse gases has seemingly changed Earth's atmosphere, which has raised Earth's equilibrium temperature.

  3. Too Weak14% picked this

    New scientific evidence shows that the earth's equilibrium temperature has been rising in a way that is consistent with the greenhouse theory, but that

    This is too lukewarm of an endorsement for greenhouse theory: the new data is consistent with greenhouse theory (doesn't contradict it), but it's not as bad as greenhouse predicted. The main point (final sentence) says that, the greenhouse theory is the best explanation we have. If that's the author's conclusion, then her main point would not choose to emphasize disappointment with the greenhouse theory. The old data was not as bad as greenhouse theory originally predicted, because scientists hadn't realized that one effect of industry (putting more gross sulfate particles in the atmosphere) would actually have a bit of a global cooling effect, since those particles reflect sunlight away before they can hit Earth. Once they started calculating in that cooling effect from sulfates, the new data matches well.

  4. Correct76% picked this

    Recent scientific data and calculations support the claims that the earth's atmosphere is becoming warmer and that the greenhouse effect is a

    Why this is right

    This is a pretty sterling match for our final sentence. It covers that earth's atmosphere is warming, and that greenhouse gases are the most likely suspect for why that is the case. The "recent data" refers to evidence in the 1st paragraph that clarifies how Earth's current warming is truly exceptional. The "recent calculations" refers to the end of the 2nd paragraph, where we factor in sulfates and get our greenhouse model to better match the climate data.

    Skill tested: Main Point · how this choice captures the passage's function is the move to repeat next time.

  5. Opposite: only if combined4% picked this

    The greenhouse theory is a reasonable explanation of a recent upward trend in the earth's atmospheric temperatures only if it is

    First of all, our main point sentence (final sentence) says nothing about "solar-fluctuation theory". This answer starts off sounding just like the final sentence. If stopped at the word "temperatures", it would be totally acceptable as a correct answer. But the tack on conditional is saying something incredibly strong about solar-fluctuation theory, which was not in our author's conclusion. Furthermore, she actually rejects the viability of solar-fluctuation theory en route to endorsing the likely legitimacy of greenhouse theory. Solar-fluctuation theory was not able, she said, to account for fluctuations in temperature as big as what we've observed recently.

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