Study: Mega-Droughts Could Become The New Normal

Researchers say large sections of the United States will endure "persistent droughts" in the coming decades that will be worse than anything experienced in the past 1,000 years.

Comparing the conditions to the Dust Bowl but lasting several decades, researchers writing in the journal Science Advances warned Thursday that the Southwest and Great Plains will be hit by these "mega-droughts" in the later part of the 21st century. Such events have been linked to the fall of civilizations, including the decline of the Anasazi, or Ancient Pueblo Peoples, in the Colorado Plateau in the late 13th century.

To come up with these projections, researchers turned to the North American Drought Atlas which recreates the history of drought over the previous 2,005 years, based on hundreds of tree-ring chronologies, gleaned in turn from tens of thousands of tree samples across the United States, Mexico and parts of Canada.

Taking the Atlas data, they then applied three different measures of drought - two soil moisture measurements at varying depths, and a version of the Palmer Drought Severity Index, which gauges precipitation and evaporation and transpiration. After that, the researchers applied 17 different climate models to analyze the future impact of rising average temperatures on the regions and compared two different global warming scenarios - a continued rise in greenhouse gas emissions and one where they are moderated.

The results, according to the study, point to a "remarkably drier future that falls far outside the contemporary experience of natural and human systems in Western North America, conditions that may present a substantial challenge to adaption."

Today, 11 of the past 14 years have been drought years in much of the American West, including California, Nevada, New Mexico and Arizona and across the Southern Plains to Texas and Oklahoma, according to the U.S. Drought Monitor, a collaboration of U.S. government agencies.

The current drought directly affects more than 64 million people in the Southwest and Southern Plains, according to NASA, and many more are indirectly affected because of the impacts on agricultural regions.