Climate change has stolen more than a billion tons of water from the West’s most vital river

Declining snowpack is causing water supplies for the Colorado River to evaporate, new study finds

February 20, 2020 at 2:00 p.m. EST

The Colorado River winds its way along the West Rim of the Grand Canyon in the Hualapai Indian Reservation on Jan. 10, 2019, near Peach Springs, Arizona. (Justin Sullivan/Getty Images)

The Colorado River’s average annual flow has declined by nearly 20 percent compared to the last century, and researchers have identified one of the main culprits: climate change is causing mountain snowpack to disappear, leading to increased evaporation.

Up to half of the drop in the Colorado’s average annual flow since 2000 has been driven by warmer temperatures, four recent studies found. Now, two U.S. Geological Survey researchers have concluded that much of this climate-induced decline — amounting to 1.5 billion tons of missing water, equal to the annual water consumption of more than 10 million Americans — comes from the fact that the region’s snowpack is shrinking and melting earlier. Less snow means less heat is reflected from the sun, creating a feedback loop known as the albedo effect, they say.