Snow Drought Across the US West Linked Directly to Climate Change

A new peer-reviewed attribution study has directly linked the extreme snow drought affecting the western United States and Canada to anthropogenic climate change, finding that the combination of reduced snowfall and accelerated spring melt is now measurably outside the range of natural variability. The western snowpack — which acts as a natural reservoir releasing water through summer — has declined sharply across the Sierra Nevada, Cascades, and Rocky Mountains, regions that supply water to tens of millions of people and hundreds of thousands of acres of irrigated farmland.

The political economy of snow drought is distinctive: unlike a sudden flood or wildfire, snowpack loss is gradual and invisible until summer water shortages hit. Water utilities, agricultural irrigation districts, and hydroelectric operators all depend on snowmelt timing and volume, but their planning models were calibrated on 20th-century snowpack data that climate change has now rendered unreliable. Adapting means either investing in expensive surface water storage, accelerating efficiency gains in agriculture (the dominant water user), or accepting that some irrigated agriculture in the region is no longer viable — each option with a different set of political losers.

The study's key open question is whether the pace of snowpack loss will trigger formal renegotiation of the Colorado River Compact and other western water-sharing agreements — agreements built on assumptions of water availability that no longer reflect physical reality.