Study attributes 40% of Western snowpack decline to emissions from 122 major companies
A new peer-reviewed study finds that climate change from greenhouse gas emissions over the past 70 years has caused a 36% decline in average annual mountain snowpacks in the Western U.S., with about 40% of that decline linked to just 122 oil, gas, coal, and cement companies. The annual water loss attributable to these companies equals the capacity of Lake Mead. The study also attributes about half of the region's streamflow declines and increased irrigation needs to these companies' emissions.
Published in Communications Earth & Environment on August 25, the study was authored by nine researchers from UC Merced and the Union of Concerned Scientists. It attributes emissions to 122 major fossil fuel and cement producers using publicly reported production data and standard emission formulas; that list has since expanded to 178 entities.
The analysis links these emissions to a 36% drop in average annual snowpack, a 13% decline in mountain streamflows, and a 4.3% rise in irrigation demand. The water loss tied to the 122 companies equals Lake Mead's full capacity, while the region's two-decade megadrought has already forced farmers to over-pump groundwater, causing land subsidence and crop abandonment.
This study could reshape how communities and policymakers view corporate responsibility for regional water crises. Farmers and municipal water managers may face increased pressure to account for climate-driven shortages, potentially leading to stricter emissions regulations or litigation against major producers. Residents in drought-stricken cities like Phoenix and Las Vegas could see higher water costs or more aggressive conservation mandates, while agricultural regions may need to adapt irrigation practices. The attribution science may also influence insurance and investment decisions, though its societal impact depends on how courts and legislatures respond.