Polar and Mountain Microbial Communities Depend on a Stable Cryosphere

Nature Reviews Microbiology, 5 November 2025

This review summarizes the harmful impacts of snow and ice loss on microbial communities uniquely adapted to thrive in these cold environments, posing downstream risks to food and income security, water availability, and human health. In the cryosphere, microbes grow in pools or streams of water across glacial, permafrost and sea ice habitats. The combination of subzero temperatures and high salinities leads to special species that flourish in their extreme environment; however, that means when temperatures become more moderate and ice melts, more common species can outcompete them and cold-adapted species must acclimate. Microbes draw down many key nutrients, and often trap that organic matter in a frozen state until it is released when thawed. Loss of these specially-adapted nutrient stores alters the landscape’s biogeochemistry and the timing of seasonal cycles, with far-reaching consequences ranging from pervasive growth of harmful algae blooms in Arctic seas, to microbial growth darkening the surface of glaciers and increasing melting and ice loss.

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