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How does deep snow help small rodents survive the Arctic winter?

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tundra biome — Polar ecosystem Southern limit of Arctic tundra and approximate line of demarcation between Low and High Arctic.

Deep snow plays a critical role in the survival of small Arctic rodents, such as lemmings, by providing a vital insulating layer against the harsh winter environment.12

During the long Arctic winter, these rodents remain active beneath the snowpack, where they construct nests and feed on the roots of grasses and sedges at the ground's surface. This layer of snow acts as an insulator, protecting the animals from extreme cold and drying conditions that would otherwise be lethal. In some cases, the protection provided by this insulative layer is sufficient to allow lemmings to continue reproducing throughout the winter months.12

While deep, soft snow is beneficial for these small mammals, it contrasts with the effects of wind-compacted snow, which can hinder the movement and foraging abilities of larger herbivores. By utilizing the space between the ground and the snow cover, small rodents are able to maintain their activity levels and survive the severe environmental extremes of the polar region.12