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?
- Secondary feedback processes involving oceanic currents and atmospheric circulationCevap
- BOrbital forcing acting entirely in isolation from planetary feedback loops
- CDeep-sea sediment deposits that redistributed solar radiation across both hemispheres
- DProlonged summer solar radiation anomalies occurring exclusively at perihelion
- EAccurate timeline calculations of glacial maxima corroborated by late-nineteenth-century geologists