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How did increased ice cover create an albedo feedback during glacial periods?

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Quaternary paleogeography — Quaternary Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the Quaternary Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

During glacial periods, the expansion of ice cover initiated a positive climate feedback loop known as the ice albedo feedback.

This process functions because ice and snow possess a much higher albedo—or reflectivity—than darker surfaces like open water or bare land. As continental ice sheets developed and expanded, they reflected a greater fraction of incoming solar radiation back into space rather than allowing it to be absorbed by the Earth's surface.123

This reduction in surface absorption led to further cooling, which in turn facilitated the growth of more ice. By increasing the Earth's overall reflectivity, the expansion of ice cover effectively amplified the cooling trends already underway during glacial phases, serving as a critical mechanism in the Earth's transition between glacial and interglacial states.34