Decline in Rocky Mountain Snowpack Threatens Future Water Resources in Western U.S.

Proceedings of the National Academy of Sciences, 18 July 2022

Under a high emissions scenario, 80% of the water contained within the winter snowpack across the Rocky Mountains could disappear by the end of the century. Mountain snowpack is a natural reservoir of freshwater. As it melts throughout the spring and summer, it provides a steady supply of freshwater for tens of millions in western U.S. states, who rely upon it for agriculture, industrial, and residential use. Rising global temperatures have already decreased the average amount of this available snowpack each spring. When the snowpack fails to produce reliable runoff, the amount and timing of water resources becomes increasingly dependent on far less predictable episodes of rain, which also tend to run off more quickly, especially with rising areas of wildfire scars that hold less water in burned soils (that also associated with global warming). More snow-free days each year strains water resources in many areas across the Northern Hemisphere, drying out soils and further heightening the risk of wildfire. Projections show that even more severe future impacts on snowpack, runoff, ecosystems and human communities would almost certainly be avoided by curbing emissions to remain at or below the 1.5°C limit of the Paris Agreement.

https://www.pnas.org/doi/abs/10.1073/pnas.2202393119