Changes in Mountain Snowpack

Temperature and precipitation are key factors affecting snowpack, which is the amount or thickness of snow that accumulates on the ground. In a warming climate, more precipitation will be expected to fall as rain rather than snow in most areas—reducing the extent and depth of snowpack. Higher temperatures in the spring can cause snow to melt earlier. Mountain snowpack plays a key role in the water cycle in western North America, storing water in the winter when the snow falls and releasing it as runoff in spring and summer when the snow melts. Millions of people in the West depend on the melting of mountain snowpack for power, irrigation, and drinking water.

In most western river basins, snowpack is a larger component of water storage than human-constructed reservoirs. Changes in mountain snowpack can affect agriculture, winter recreation, and tourism in some areas, as well as plants and wildlife. For example, certain types of trees rely on snow for insulation from freezing temperatures, as do some animal species. In addition, fish spawning could be disrupted if changes in snowpack or snowmelt alter the timing and abundance of streamflows.

Learn More

• Attribution of declining western U.S. snowpack to human effects
• Climate change impacts on maritime mountain snowpack in the Oregon Cascades
• Climate Change in Colorado A Synthesis to Support Water Resources Management and Adaptation
• Mountain Snowpack in the West and Southwest, UOA
• Indicators: Snowpack, Snowpack Trends, EPA
• Variability and trends in Mountain Snowpack in Western North America