When it comes to global warming’s one-two punch of inundation and drought, the presence of too much water has had the most impact on U.S. agriculture this year, with farmers in the Midwest swamped by flooding throughout the Mississippi Basin.
But in the Southwest, it’s the increasing lack of water that’s threatening the agricultural economy, as well as the welfare of 40 million Americans and part of the food supply for the entire nation.
The 1,450-mile-long Colorado River serves as a source of water for seven states, but climate change and overuse have caused its levels to drop precipitously. From 2000 to 2014, flows declined 19% from the 20th century average, according to American Geophysical Union Water Resources research. By 2100, the river flow could fall as much as 55%.
The threat to fresh water is of course global in scope. Last week, the World Resources Institute reported that access to water for hundreds of millions of people is now at risk due to global warming. Along the Colorado River, climate change is also taking its toll, responsible for aridification—the progression from cyclical drought to a permanent decrease in water.