Reading Comprehension

PT106 · S4 · P2 · Q8 Volcanoes

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Long after the lava has cooled, the effects of a major volcanic eruption may linger on.

Topic

The lingering climate effects of major volcanic eruptions and how they influence global and regional temperatures.

Framework

Present Debate

Main Point

While volcanic eruptions are thought to cool Earth's climate, recent research suggests the cooling effect is smaller and more complicated than previously believed, with global impacts being minor but potential for larger regional effects due to feedback loops. (The “most valuable sentence” encapsulating the main point appears in P3: )

P1: Common Belief about Volcanic Eruptions

After a big volcano erupts, the dust and acid it throws into the air can cool the planet by blocking sunlight—some even blame Tambora’s 1815 eruption for an entire summer without warm weather in 1816.

P2: New Findings Challenge Conventional Wisdom

Scientists Mass and Portman say this connection isn’t quite as strong as we think. By analyzing global temperatures around nine eruptions—while accounting for El Niño’s effects—they find the supposed volcanic cooling can be tricky to pin down.

P3: Refining the Evidence—What Eruptions Really Do

Once they filtered out El Niño, they saw that smaller eruptions don’t noticeably affect temperatures, and even huge eruptions only slightly cool the hemisphere—much less than earlier studies had claimed.

8.

The passage indicates that each of the following can be an effect of the El Niño phenomenon EXCEPT:

  1. making the cooling effect of

    Supported

    At the end of the 2nd paragraph, it's saying that El Niño can "mimic volcanic cooling, if the volcano erupts just as El Niño is beginning to fade". El Niño warms the sea and the air, so when it fades, things get cooler. If a volcano happens right when El Niño is fading, then we might mistakenly think the cooling is from the volcano, even though the volcano might be too minor to have actually resulted in any cooling.

    18% picked this

  2. making the cooling effect of

    Supported

    At the end of the 2nd paragraph, it's saying that El Niño can "mask the cooling brought about by an eruption". El Niño warms the sea and the air, so when it arrives things get warmer. If there were a volcano that would have been followed by cooling, but that happens right when El Niño shows up, then the cooling form the volcano will be masked / offset / hidden by the warming from the El Niño.

    15% picked this

  3. increasing atmospheric temperature through cyclic

    Supported

    At the end of the 2nd paragraph, it's saying that El Niño "warms the sea surface in the equatorial Pacific and thereby warms the atmosphere". Where does this cyclic warming come from? That modifier is fair game because El Niño is a cyclic phenomenon.

    4% picked this

  4. Correct

    initiating a feedback loop that

    Why this is right

    This is talking about climatic feedback loops, which shows up in the final paragraph, after we're done talking about El Niño. El Niño was clouding our volcanic-cooling data. Once we accounted for it, we realized that volcanoes don't really have that big an effect on climate. But then some researchers were saying, "Okay, but even if volcanoes don't have big impact on global temperature, they could still have big regional impacts on weather via feedback loops." Feedback loops were never being connected to El Niño.

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

    56% picked this

  5. confounding the evidence for a

    Supported

    This is basically the same as what (A) and (B) were talking about. This is just lumping together the two different ways that El Niño can mess with our volcano-climate relationship. We also can lean on the first sentence of the 3rd paragraph for support: Once El Niño effects had been subtracted from the data, the actual effects of the eruptions came through more clearly. That means that when El Niño effects are included in data, the actual effects of the volcano-climate connection does not come through clearly. It is confounded.

    7% picked this

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