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Question

Difficulty: MediumExplicit Detail Retrieval

Passage:
In 1864, self-taught Scottish polymath James Croll proposed that orbital eccentricity variations, coupled with precession, initiated ice ages by altering winter solar radiation in the Northern Hemisphere. Unlike later refinements by Milutin Milankovitch, Croll hypothesized that glaciation occurred when winter coincided with aphelion during periods of high eccentricity, causing prolonged cold winters that allowed snow accumulation. Crucially, Croll posited that this thermal asymmetry triggered secondary feedback mechanisms—specifically, altered oceanic currents and atmospheric circulation—which amplified the cooling effect rather than orbital forcing acting in isolation. Although Croll's model accounted for astronomical cycles, it miscalculated the timing of past glacial maxima, leading late-nineteenth-century geologists to temporarily reject astronomical climate theory until deep-sea sediment cores corroborated Milankovitch's recalibrated calculations in the mid-twentieth century.

According to the passage, Croll maintained that the climate cooling during glacial periods was amplified by which of the following?

  1. Secondary feedback processes involving oceanic currents and atmospheric circulationAnswer
  2. B
    Orbital forcing acting entirely in isolation from planetary feedback loops
  3. C
    Deep-sea sediment deposits that redistributed solar radiation across both hemispheres
  4. D
    Prolonged summer solar radiation anomalies occurring exclusively at perihelion
  5. E
    Accurate timeline calculations of glacial maxima corroborated by late-nineteenth-century geologists

Answer

Secondary feedback processes involving oceanic currents and atmospheric circulation
The passage explicitly notes that Croll posited secondary feedback mechanisms, specifically altered oceanic currents and atmospheric circulation, which amplified the cooling effect.

Step-by-Step Solution

1
Identify the key term in the prompt
The prompt asks what Croll claimed amplified climate cooling during glacial periods.
Explicit detail retrieval requires matching the question's focus directly to the passage statement.
2
Locate the explicit detail in the text
Found the third sentence: 'Crucially, Croll posited that this thermal asymmetry triggered secondary feedback mechanisms—specifically, altered oceanic currents and atmospheric circulation—which amplified the cooling effect...'
This direct statement provides the precise cause of the amplified cooling effect.
3
Match the passage detail with the correct answer choice
The statement directly corresponds to the choice describing secondary feedback processes involving oceanic currents and atmospheric circulation.
Paraphrasing accurately preserves the explicit meaning without adding unstated extrapolations.

Key Concept

Explicit detail retrieval requires locating directly stated facts and matching accurate paraphrases without overgeneralizing or introducing outside information.
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Topics

Explicit Detail Retrieval

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