Tuesday, 25 August 2026

Climate change stripped more than a third of the American West's typical annual snowpack and cut streamflows by about 13 percent between 2014 and 2024, according to a study published in Nature's Communications Earth and Environment journal and reported by Inside Climate News. About half of those water losses trace to emissions from 122 fossil fuel companies and cement producers, the group known as carbon majors, the study concluded.

The damage concentrates in the Colorado River's lower basin. Snow water equivalent there fell by 76 percent over the same decade, and streamflow dropped 21 percent, according to the paper.

Warming did not only shrink supply. Irrigation demand across the West rose by over 4 percent from 2014 to 2024, with just over half of that increase driven by carbon majors' emissions, the study found.

The attribution rests on a cumulative emissions ledger. Carbon Majors estimates that 178 entities have emitted the equivalent of 1.44 trillion tons of carbon dioxide since the start of the Industrial Revolution.

The hydrology sits inside an active legal fight over allocation. Nevada sued the federal government over its plan for managing the Colorado River, a system that supplies 40 million people with water for cities, farms and businesses, Inside Climate News reported.

The combination of a 21 percent streamflow decline in the lower basin and rising irrigation demand narrows the volume available to the states, tribes and utilities that draw on the river. Hydropower, municipal supply and agricultural users all depend on the same reservoir storage that the snowpack losses feed.

The paper's method matters for litigation. By assigning a share of measured snowpack and streamflow loss to a defined list of 122 corporate emitters, the authors convert a diffuse climate signal into a quantified, named exposure. That is the structure plaintiffs need to link a specific defendant to a specific physical harm in a specific basin.