Could the southwest of the U.S. be in for a megadrought?

From Mother Jones

A new study by Cornell University, the University of Arizona, and the US Geological Survey researchers, looked at the deep-historical record (tree rings, etc.) and the latest climate change models to estimate the likelihood of major droughts in the Southwest over the next century. The results are as soothing as a thick wool sweater on mid-summer desert hike. 

The researchers concluded that odds of a decade-long drought are “at least 80 percent.” The chances of a “mega-drought,” one lasting 35 or more years, stands at somewhere between 20 percent and 50 percent, depending on how severe climate change turns out to be. And the prospects for an “unprecedented 50-year megadrought”—one “worse than anything seen during the last 2000 years”­—checks in at a non-trivial 5 percent to 10 percent.

It gets worse

his (paradoxically) chilling assessment comes on the heels of another study (study; my summary), this one released in early August by University of California-Irvine and NASA researchers, on the Colorado River, the lifeblood of a vast chunk of the Southwest. As many as 40 million people rely on the Colorado for drinking water, including residents of Las Vegas, Los Angeles, Phoenix, Tucson, and San Diego. It also irrigates the highly productive winter farms of California’s Imperial Valley and Arizona’s Yuma County, which produce upwards of 80 percent of the nation’s winter vegetables.

The researchers analyzed satellite measurements of the Earth’s mass and found that the region’s aquifers had undergone a much-larger-than-expected drawdown over the past decade—the region’s farms and municipalities responded to drought-reduced flows from the Colorado River by dropping wells and tapping almost 53 million acre-feet of underground water between December 2004 and November 2013—equal to about 1.5 full Lake Meads, drained off in just nine years, a rate the study’s lead researcher, Jay Famiglietti, calls “alarming.”

Considering how much of the Colorado River Basin, which encompasses swaths of Utah, Colorado, California, Arizona, and New Mexico, are desert, it’s probably not wise to rapidly drain aquifers, since there’s little prospect that they’ll refill anytime soon. And when you consider that that the region faces high odds of a coming mega-drought, the results are even more frightening. (Just before Labor Day, over fierce opposition from farm interests, the California legislature passed legislation that would regulate groundwater pumping—something that has never been done on a state-wide basis in California before. Gov. Jerry Brown is expected to sign it into law.)

Lake Mead Is Drying Up

This is bad and reminds me of what Thomas Homer-Dixon wrote in The Ingenuity Gap when he was shocked that no one in Las Vegas was calculating projected droughts (which have arrived)

Lake mead nevada all time low fe

The water level at Lake Mead dropped to a new record low this week, but it hasn’t hit rock bottom—yet.

As of Tuesday, Lake Mead was at about 39 percent of its capacity. The drought has taken a toll on water resources, resulting in precautionary actions such as a decreased flow allowance into Hoover Dam to protect current distribution policies. 

The projected lake level is at about 1,082 feet above sea level, and officials say they can meet water obligations at least through next year without a key shortage declaration. But if the water level drops below the 1,075-foot trigger point, Arizona and Nevada will face water delivery cuts, according to the Washington Times.

The lake is currently storing 10.2 million acre-feet of water. Lake Powell, the reservoir managed in conjuction with Lake Mead and located farther up the Colorado River, is holding 12.7 million acre-feet of water—or 52 percent of its capacity.

Remains of a River: source to sea down the Colorado

From October 2011 to January 2012, Will Stauffer-Norris and Zak Podmore hiked and paddled from Wyoming’s Wind River Mountains to Mexico following the Colorado River system from its farthest inland source to the sea, filming and narrating on the fly. The resulting film, Remains of a River, is an unforgettable story of friendship, adventure and environmental degradation.

The Colorado River Runs Dry

The United States and Mexico are trying to fix that

Until 1998 the Colorado regularly flowed south along the Arizona-California border into a Mexican delta, irrigating farmlands and enriching a wealth of wildlife and flora before emptying into the Gulf of California.

But decades of population growth, climate change and damming in the American Southwest have now desiccated the river in its lowest reaches, turning a once-lush Mexican delta into a desert. The river’s demise began with the 1922 Colorado River Compact, a deal by seven western states to divide up its water. Eventually, Mexico was allotted just 10 percent of the flow.

Officials from Mexico and the United States are now talking about ways to increase the flow into the delta. With luck, someday it may reach the sea again.

It is paradoxical that the Colorado stopped running consistently through the delta at the end of the 20th century, which — according to tree-ring records — was one of the basin’s wettest centuries in 1,200 years. Now dozens of animal species are endangered; the culture of the native Cocopah (the People of the River) has been devastated; the fishing industry, once sustained by shrimp and other creatures that depend on a mixture of seawater and freshwater, has withered. In place of delta tourism, the economy of the upper Gulf of California hinges on drug smuggling operations that run opposite to the dying river.