The basin has continued to experience droughts this decade — in 2012, 2013 and 2017 — but their severity in comparison with historic drought is unknown. The “Turn-Of-The-Century Drought” study, published Monday in the Proceedings of the National Academy of Sciences, focused only on the 10 years after 2000.
“In terms of the most severe flow deficits, the driest years of the Turn-Of-The-Century-Drought in the [Upper Missouri River Basin] appear unmatched over the last 1,200 years,” the study said. “Only a single event in the late 13th century rivaled the greatest deficits of this most recent event.”
Researchers familiar with drought of this magnitude in the dry Southwest were surprised to find it in the Midwest. The Missouri River winds 2,300 miles from western Montana to St. Louis, where it joins the Mississippi River. It runs through the Dakotas and past Nebraska, Iowa, Kansas and Missouri, where it supports farming in several states and provides fresh water for dozens of municipalities.
“We don’t tend to think of the upper Missouri region as being as drought-threatened as a region like the Southwest United States,” said Erika Wise, an associate professor in the geography department at the University of North Carolina at Chapel Hill and study co-author.
“These findings show that the upper Missouri Basin is reflecting some of the same changes that we see elsewhere across North America, including the increased occurrence of hot drought” that’s more severe than usual, Wise said.
The study is the latest to show how human-influenced climate change threatens to reshape the landscape by making naturally occurring drought far more severe.
A study published last month in the journal Science found that a vast region of the western United States — California, Arizona and New Mexico north to Oregon and Idaho — is already in the grips of the first climate change-induced megadrought.
Scientists at NASA and Columbia University had predicted such a drought would start sometime around 2030, but last month’s study showed that the phenomenon is already here. “The megadrought era seems to be reemerging, but for a different reason than the [past] megadroughts,” said Park Williams, the study’s lead author and a researcher at the Lamont-Doherty Earth Observatory at Columbia University.
Prolonged drought can disrupt agriculture and hurt economies, the researchers said. It affects dams that manage water resources and slows commercial traffic in rivers. On top of that, it harms marine life that must cope with lower water levels and animals such as waterfowl that rely on fish to survive. Runoff from the mountains to the Upper Missouri started decreasing in the 1950s, then dramatically declined between 1980 and 2000, the study said.
“Future warming is anticipated to cause increasingly severe droughts by enhancing water deficits that could prove challenging for water management,” the Missouri River study said. Historically, the Upper Missouri accounts for about 30 percent of the total flow at the mouth of the Missouri and will diminish over time, the authors said.
“The watershed is a critical source of water for the region — supporting megafarms, hydropower, tourism, and healthy ecosystems,” one author said. Declines in stream flow will be felt downstream on farms from Iowa to Missouri, especially if the southern part of the Missouri River experiences drought when the northern portion is dry.