Two scientists say global warming is shrinking the most important waterway in the American Southwest and could reduce its flow by more than a third by the end of the century.
Researchers from Colorado State University and the University of Arizona say the Colorado River's volume dropped more than 19 percent during a drought gripping the region since 2000, and a shortage of rain and snow can account for only about two-thirds of that loss.
They concluded the rest of the decline is due to global warming, which draws more moisture out of waterways, snowbanks, plants and soil in the Colorado River Basin.
Their projections could signal problems from Colorado to California and Mexico. The river supplies water to about 40 million people and 6,300 square miles of farmland.