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How did changes in Earth’s orbit influence Pleistocene climate cycles?

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Map showing the extent of the Laurentide, Cordilleran, and Greenland ice sheets during the Wisconsin glaciation, roughly 100,000 to 11,000 years ago. The Laurentide Ice Sheet covers most of present-day Canada and parts of the northern United States in light blue, the Cordilleran Ice Sheet covers the Pacific Northwest in teal, and the Greenland Ice Sheet is marked in purple. Modern international and state or provincial boundaries are outlined for reference. — Pleistocene Epoch Ice sheets during the Wisconsin glacial episode penetrated deep into North America.

During the Pleistocene Epoch, changes in Earth’s orbit acted as the "pacemaker" for climate cycles by altering the seasonal and latitudinal distribution of solar radiation reaching the planet. These Milankovitch cycles are driven by three primary orbital parameters:12

Eccentricity: The 100,000-year cycle describing the shape of Earth’s orbit as it shifts between nearly circular and elliptical.13
Obliquity: The 41,000-year cycle of the tilt of Earth’s axis, which influences the intensity of seasonal contrasts.13
Precession: The 19,000- to 23,000-year cycle involving the "wobble" of Earth’s axis and the rotation of its orbital ellipse.13

The astronomical theory emphasizes that glaciations were triggered when these parameters resulted in low summer insolation in the high-latitude Northern Hemisphere, allowing winter snow to persist through the summer. Because these orbital variations alone are relatively small, they are amplified by feedback mechanisms—such as changes in albedo from snow cover and fluctuations in atmospheric carbon dioxide—to produce the significant climatic shifts observed in the Pleistocene Epoch.1