Fossil fuel emissions linked to half of Western US water losses

A new study by the University of California, Merced, and the Union of Concerned Scientists reveals that emissions from major fossil fuel and cement companies have driven approximately half of the climate-related reductions in water sources across the western United States between 2014 and 2024.

The research indicates that climate change has reduced April snowpack by about 36 percent and warm-season streamflow by roughly 13 percent in the region. Since 1950, the cumulative water loss linked to emissions from 122 major companies, known as Carbon Majors, is equivalent to the total capacity of Lake Mead. Additionally, the study found that emissions-driven temperature increases have raised irrigation demand by 2.4 percent.

In California’s Central Valley, one-tenth of observed groundwater loss is tied directly to these corporate emissions. The report also notes shifts in streamflow timing, with peak flows arriving up to 30 days earlier in some mountain basins, creating mismatches between water availability and agricultural or landscaping needs.