PrepTest 106

[lcid:3523] Prep Test 106 LSAT — Reading Comp — S4 Reading comp

Passage

Questions 6-13  .        Long after the lava has cooled, the effects of a  . major volcanic eruption may linger Remaining source text redacted.
Passage walkthrough
Passage Summary

Topic: Science


Paragraph 1

  • Paragraph note
    • Atmospheric debris produced by a major volcanic eruption has been hypothesized to have a cooling effect on Earth’s climate.
  • Views, minor Meta-Structures, and the author's attitude
    • Fine dust and sulfuric acid droplets from an eruption can block sunlight, which is believed to result in a drop in Earth’s temperature.
    • Example: many believe the Tambora eruption in 1815 for the Earth’s “year without a summer” of 1816.
    • Author’s attitude: “may linger on” (first sentence); “persist for years” (first sentence); “researchers have generally thought” (second sentence); “many blame” (third sentence)

Paragraph 2

  • Paragraph note
    • According to Clifford Mass and Davit Portman, volcanic eruptions don’t cause as much cooling as previously believed.
  • Views, minor Meta-Structures, and the author's attitude
    • Mass and Portman conducted an analysis of nine volcanic eruptions, tracking global climate data for the years before and after
      • Examples: El Chichon in 1982 and Krakatau in 1883
      • Filtered out effect of El Nino-Southern Oscillation
        • El Nino warms the atmosphere - can mask cooling from an eruption but can also mimic cooling effect of an eruption if it ends as an eruption occurs
      • Author’s attitude: “seems plausible” (first sentence); “not as strong” (first sentence); “can mask the cooling” (fourth sentence); “can also mimic volcanic cooling” (fourth sentence)

Paragraph 3

  • Paragraph note
    • Mass and Portman: minor eruptions have no effect on global temperature, while major eruptions cause a smaller drop than expected.
  • Views, minor Meta-Structures, and the author's attitude
    • Mass and Portman’s analysis:
      • Accounted for El Nino
      • Major explosions that spit dust lower average temperature by half a degree centigrade or less in the hemisphere (northern or southern) where eruption occurred and in the opposite hemisphere
    • Author’s attitude: “came through more clearly” (first sentence); “contrary to what earlier studies had suggested” (second sentence); “no discernible effect” (second sentence); “cause a smaller drop than expected” (third sentence); “only half a degree” (third sentence)

Paragraph 4

  • Paragraph note
    • Other researchers argue that a small temperature drop from an eruption can cause a significant decrease in regional temperature due to feedback loops.
  • Views, minor Meta-Structures, and the author's attitude
    • Example of feedback loop: small temperature drop in NE US in early spring delays melting of snow, which leads to increased reflection of sunlight, which increases cooling.
      • Unusually cool air causes jetstream to move farther south than normal, causing more cold air to come in behind it, which further deepens cooling
      • This effect could cause the “year without a summer”
    • Author’s attitude: “could result in a significant regional fluctuation” (first sentence) “amplified by climatic feedback loops” (first sentence); “could, in turn, affect the jet stream” (third sentence); “could cause the stream to wander” (fifth sentence); “could be blown up” (sixth sentence)

Main Point: According to new research, major volcanic eruptions cause a smaller decrease in global temperature than previously hypothesized, but can have a significant depressive impact on regional temperature via feedback loops.

Key Lines?

Paragraph 1, Sentence 2 (P1, S2) - Introduces volcano-climate hypothesis

P3, S3 - Mass and Portman show eruptions cause small decrease in global temperature

P4, S2 - Small decrease hypothesized to lead to significant regional decrease due to feedback loops

Meta-Structure?

Reporting a Viewpoint: This passage uses a “Reporting a Viewpoint” Meta-Structure. The first paragraph introduces the topic of the passage: the hypothesis that dust thrown up by a volcanic eruption blocks sunlight and leads to a decrease in Earth’s average temperature (P1 S2). The author summarizes the research of Clifford Mass and Davit Portman, whose analysis shows that, contrary to earlier research, the effect of a major volcanic eruption on global temperature would be small (P2 S1, P3 S3). Finally, the author relates that other researchers hypothesize that climatic feedback loops could amplify even a small decrease in temperature to cause significant drops in regional temperature (P4 S1).

The main point in a Reporting A Viewpoint passage is the view held by the subject, in this case, Mass, Portman, and the other group of researchers mentioned in the fourth paragraph who posit the feedback loop hypothesis. The author does a clear and neutral job of tracing the volcano-climate hypothesis from its origins, through Mass and Portman’s research, to the feedback loop hypothesis. The author’s own opinion is largely absent from the passage.

Last Thoughts?

Initially, this passage begins with the idea that scientists have believed the cooling effect of a volcanic eruption on global temperature to be significant. In fact, the author writes, people believe an eruption could cause a year without a summer. Then the author describes the research of Mass and Portman, stating that they believe the global effect of a major eruption is much less significant than previously believed. This statement seems to counter the original belief that eruptions have a significant climatic effect. Finally, the author discusses the hypothesis that climatic feedback loops can cause a large decrease in regional temperature, which could result in a year without a summer.

So the key distinction the author makes in the passage seems to be between the global effect of a major volcanic eruption and the regional effect of such an eruption. This distinction is key, and is something the careful test-taker should make note of.

Question prompt

The author of the Remaining source text redacted.
Why the credited answer is right

Credited answer: C

The notes below walk through why it fits the stem and how to eliminate the rest.

Question Type

Science

Strategy Overview

Review the main point, and use notes or highlighted/underlined text in the passage to recall the author’s attitude, and find the answer that best reflects your understanding of the main point/author’s attitude.

Answer Anticipation

This question asks us about the author's view, but doesn't provide any insight into the topic of the correct answer or where the supporting information might show up in the passage. This means the correct answer is likely to relate back to the author's main point. As such, we'll need to rely on our big-picture understanding of the passage to answer this question. We should start by reminding ourselves of the main point (either by reviewing what we said after reading the passage or by rereading our answer to the main point question). We can also review any notes about the author's attitude or any text we highlighted because it expressed the author's opinion. After doing that, we can head to the answer choices, tabling those that don't line up with the main point. For those answer choices that conform to the author’s main point, we'll use our notes and the passage to see if it's correct.In this case, the author’s attitude is absent from the passage; the author neutrally presents the research and views of Mass, Portman, and other scientists who have studied the volcano-climate hypothesis. As we have seen, the views of the scientists the author talks about don’t contradict each other; indeed, the author presents the evidence for the global temperature drop due to volcanic eruptions and the regional feedback loop hypothesis as complementary. So, in this question, we need to consider whether the hypotheses presented in the answer choices are in line with the views and research of the scientists the author has written about.

Answer choices

  1. A
    Major volcanic eruptions sometimes Remaining source text redacted.
    Why choice A is not credited

    (A) Does this answer choice describe a hypothesis that is in line with the author’s main point and the views expressed by the subjects of the passage?

    No. This answer choice is contradicted by P3 S3, where the research of Mass and Portman led to the conclusion that major eruptions only cause temperatures to drop by half a degree centigrade or less in the hemisphere in which the explosion occurred. So this answer choice is inaccurate and can be eliminated.

  2. B
    Major volcanic eruptions can Remaining source text redacted.
    Why choice B is not credited

    (B) Does this answer choice describe a hypothesis that is in line with the author’s main point and the views expressed by the subjects of the passage?

    No. This answer choice is totally unsupported by the passage. The author discusses in P2 S3-4 that El Nino can confound the research being done into what the true effect of volcanic eruptions on global temperature is, but there is no implication that eruptions cause El Nino. This is not the right answer choice.

  3. C
    Major volcanic eruptions do Remaining source text redacted.
    Why choice C matches the stem

    (C) Does this answer choice describe a hypothesis that is in line with the author’s main point and the views expressed by the subjects of the passage?

    Yes. This answer choice is completely supported by the passage. First, the author cites the research of Mass and Portman that major eruptions cause only a small decrease in hemispheric temperature (P3 S3). Then, the author brings in the regional feedback loop hypothesis in which the small decrease in hemispheric temperature leads to a dramatic cooling effect in various affected regions that could, in turn, result in a year without a summer (P4 S6).

    So the effect of the volcanic eruption would be to cause a cold summer, but the eruption would not directly cause the cold summer; the effect of the eruption would have to be filtered through the regional feedback loop process first. Thus, a major eruption would indirectly cause a cold summer, which is, in effect, what (C) states.

  4. D
    The climatic effects of Remaining source text redacted.
    Why choice D is not credited

    (D) Does this answer choice describe a hypothesis that is in line with the author’s main point and the views expressed by the subjects of the passage?

    No. This answer choice is directly contradicted by P3 S2-3, where the author talks about the analysis done by Mass and Portman. They found that minor eruptions did not affect global temperature at all while major eruptions affected global temperature by decreasing it by half a degree or less in the hemisphere in which the eruption occurred (P3 S 2-3). So the difference between minor and major eruptions was not “in degree;” minor eruptions simply had zero effect on temperature, while major ones had a small effect.

  5. E
    El Ni&ntildeo has no Remaining source text redacted.
    Why choice E is not credited

    (E) Does this answer choice describe a hypothesis that is in line with the author’s main point and the views expressed by the subjects of the passage?

    No. This answer choice is unsupported by the passage. In fact, the author describes how El Nino can indeed affect atmospheric temperature to the extent that it confuses researchers trying to determine the effect of volcanic eruptions on temperature (P2 S3-4 and P3 S1).

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