Low Emissions Would Cut Western U.S. Snowpack Losses by Half

Nature, 1 April 2025

Western U.S. mountain snowpack, crucial for supplying water to roughly 100 million people and accounting for 75% of total water supply over the region, faces significant declines due to climate change. A new study consolidates climate model simulations to produce regional estimates of snow loss under multiple emissions scenarios. Research indicates that the Western U.S. will experience a 34% loss in total volumetric snowfall by 2100 under a high emissions scenario (SSP3-7.0). However, a low emissions scenario consistent with the Paris 1.5C goal (SSP1-2.6) would cut snowpack loss in half (17%), while medium emissions (SSP2-4.5) would result in 25% loss of snowpack. Worryingly, the Sierra Nevada and Cascades show a higher sensitivity to warming, losing a disproportionate 15% of annual snowfall per degree of warming, with minimal influence from precipitation changes. In contrast, the inter-mountain west is less sensitive to warming, but significantly affected by precipitation changes. These findings support the prediction of substantial snowfall reduction from global warming, with losses directly tied to future emissions levels, impacting vital regional water resources for agriculture and other uses.

Full Paper: https://www.nature.com/articles/s41612-025-01002-2