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How does the tilt of Earth’s axis affect Pleistocene glaciations?

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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.

The tilt of Earth’s axis, known as obliquity, is a fundamental component of the astronomical theory used to explain Pleistocene glaciations. This parameter refers to the angle at which Earth’s axis tilts away from a vertical line drawn to the plane of its orbit around the Sun, and it follows a cyclic frequency of approximately 41,000 years.1

Along with eccentricity and precession, obliquity determines the distribution of solar radiation across the planet's surface. In high-latitude regions, such as the Northern Hemisphere at about 55° N, the 41,000-year tilt cycle is the dominant influence on radiation levels.1

Glaciations are hypothesized to initiate during periods of low summer insolation in these high latitudes. When summer radiation is reduced, conditions become optimal for winter snow to persist throughout the summer season, eventually leading to the development of large-scale continental ice sheets. These orbital variations are widely considered the "pacemaker" of the ice ages, though feedback mechanisms like albedo and changes in atmospheric carbon dioxide are necessary to amplify these effects to the magnitude observed in the Pleistocene Epoch.1