A megadrought may soon take hold in the American Southwest, bringing the driest conditions seen in the area during the last 2,000 years. Such a drought could last up to 35 years, according to researchers, more than the three decades needed to classify the event as a megadrought.  

Cornell University researchers believe there is at least a 50 percent chance the Southwestern United States will experience a drought lasting 10 years or more sometime during the next century. The same study suggests between a 20 percent and 50 percent chance of a megadrought in some states including California, Arizona and New Mexico.

"This will be worse than anything seen during the last 2,000 years and would pose unprecedented challenges to water resources in the region," Toby Ault, assistant professor of earth and atmospheric science at Cornell, said.

The western United States is currently experiencing a drought so severe that land, unburdened by the weight of water, is beginning to rise. In California, the event is classified as a D4 drought, the most extreme category.

Ault and his team developed a new climate model that compared modern measurements with records of ancient Earth. The team believes that global warming is contributing to long-term drought in western regions of the United States.

The Dust Bowl of the 1930s that devastated crops across much of the United States came in three waves, lasting from 1934 to 1940 in most regions. Some areas suffered through the effects of the massive dust storms for a total of eight years.

"For the Southwestern U.S., I'm not optimistic about avoiding real megadroughts. As we add greenhouse gases into the atmosphere -- and we haven't put the brakes on stopping this -- we are weighting the dice for megadrought conditions," Ault stated in a press release.

Drought conditions are less likely over the coming decades in Montana, Idaho and Washington, according to the new computer model. Texas is at the greatest risk from drought, Ault and his team found. The study also found other areas around the world that could soon experience a megadrought, including the Amazon Basin, southern Africa and Australia.

Megadroughts lasting 30 years aor longer have taken place recently in Australia and sub-Saharan Africa. The Colorado River experienced also three decades of dry conditions in the middle of the 12th Century. Many areas are subject to a megadrought once every six or seven centuries.

Study of a possible megadrought in the western United States was profiled in the Journal of Climate.