snowfields

Snowfields are expansive areas of snow-covered ground that persist across seasons in high mountain or polar regions. They differ from glaciers in that most snowfields do not show reliable flow; they are zones where snow accumulation exceeds ablation over time, and the surface can melt in summer.

Formation and persistence: Snowfields form where winter snowfall, aided by low temperatures and shading, accumulates faster than it melts. They may persist for multiple seasons, slowly metamorphosing from fresh powder to denser snow and firn, but most do not fully convert to ice masses that move.

Distribution and characteristics: They occur worldwide in alpine environments—such as the Alps, Rockies, Andes, Himalayas—and in polar regions and dry high-latitude deserts where coastal or orographic conditions preserve snow. They vary from a few hectares to many square kilometers; margins are often dynamic, with active melt lines advancing upslope in summer.

Hydrology and ecology: Melt from snowfields provides freshwater for rivers and groundwater; the snow cover also influences surface albedo, temperature, and local climate. Some microbial communities and hardy lichens inhabit snowfields during melt.

Climate change and hazards: Warming temperatures reduce the extent and persistence of snowfields in many regions, altering water resources and increasing the risk of rapid retreat. Snowfields can pose hazards to backcountry travelers, including hidden crevasses and unstable snow bridges; rapid melt can trigger floods.

Monitoring and research: Scientists study snowfields using field measurements, remote sensing, and climate models to understand snowpack dynamics, hydrology, and ecosystem impacts.