A West Texas thunderstorm on July 24 kicked up a dust cloud as the winds passed over ground parched and barren from a drought that began back in 2010. As the dust passed over Interstate 20 just before 8 p.m., drivers lost sight of the road before them and quickly slowed down, setting off a chain of collisions as 17 cars and trucks ran into one another. Two 18-wheelers sandwiched one car, killing its driver and passenger.

 Nearly 60 percent of the United States, mostly in the center and west of the country, is currently experiencing moderate to exceptional drought conditions, according to the National Drought Monitor, and the drought is expected to persist into 2013 for many of those already parched states. The effects of these dry times have come in many forms: The costs of agricultural products, including beef and corn, and the food products derived from them have risen. Barges are having difficulty traversing the Mississippi River. Dry soil is causing the foundations of some homes to crack and leak. And dust storms, like the one in Texas, are echoing the 1930s Dust Bowl, the subject of a new documentary by Ken Burns that premieres on PBS this weekend.

 Drought is a natural phenomenon, especially in the semiarid Great Plains. But the way that humans interact with their environment prior to and during a drought can profoundly affect not only how well they weather such an event but also aspects of the drought itself. The Dust Bowl provides the best—or perhaps, most horrific—example of the phenomenon, but the current drought may be foreshadowing an even worse future.

 The 1930s drought, though longer, was not too unlike the one now. Scientists have traced the drought of the Dust Bowl years to abnormal sea surface temperatures. and likewise have blamed La Nina for the current drought. “Those are naturally occurring events,” says Richard Seager, a climatologist at the Lamont-Doherty Earth Observatory of Columbia University.

 Hot weather and little rain isn’t enough to create a Dust Bowl, though—humans helped. “Human-induced land degradation is likely to have not only contributed to the dust storms of the 1930s but also amplified the drought,” Seager and his colleagues wrote in a 2009 article in the Proceedings of the National Academy of Sciences. “These together turned a modest…drought into one of the worst environmental disasters the U.S. has experienced.”

 That land degradation in the late 19th and early 20th centuries came from emigrants moving into the Great Plains as the American West opened up for settlement. Lured by promises of 160 acres of land and a seemingly good climate for growing things, people flocked to the semi-arid region. Using tractors and plows, they dug up 5.2 million acres of grassland between 1925 and the early 1930s.

 Weather in the middle of the United States, then and now, is dominated by dry winds from the West but also marked by violent clashes caused by air moving in from the Arctic or the Gulf of Mexico. “It is an unreliable, intractable place, wildly oscillating around an almost meaningless mean,” University of Kansas historian Donald Worster wrote in Dust Bowl: The Southern Plains in the 1930s. 

 Wetter than average in the first decades of the 20th century, the weather of the Great Plains misled settlers, and they pushed into places not particularly suitable for agriculture. And when the pendulum had swung from wet to dry in the early 1930s, the native grasses and vegetation that had held the soil in place during previous droughts were gone, replaced by wheat and other crops that quickly withered and died under the hot sun.

 “If you get rid of plant cover, or reduce it in various ways, then more of the energy of the wind is able to get to the soil surface and therefore, you [get] more dust emission,” says Greg Okin, a University of California, Los Angeles geographer. 

 The year 1932 saw 14 dust storms, followed by 38 in 1933 and another 22 in 1934. By the middle of the decade, the people of the Great Plains knew what to do when a dust storm was on the horizon. On April 14, 1935, when Pauline Winkler Grey of Meade County, Kansas, saw a smoky grey-blue haze in the distance, her family quickly sealed the cracks around the windows in their small house, despite the heat. 

 By late afternoon, with the barometer falling rapidly, the temperature had dropped 50 degrees, heralding a cold front moving south from Canada. A huge black cloud approached from the North. “It had the appearance of a mammoth waterfall in reverse—color as well as form,” Grey would later write. “The apex of the cloud was plumed and curling, seething and tumbling over itself from north to south.” The storm swept across Oklahoma and into Texas, bringing total darkness for 40 minutes and partial for another three hours.

 The day after this “Black Sunday,” Robert Geiger, an Associated Press reporter from Denver, sent a dispatch about the storm to the Washington Evening Star: “Three little words,” he wrote “rule life in the dust bowl of the continent—if it rains.” Without intending to do so, Geiger had given the disaster, with its ongoing drought, devastated farms and frequent dust storms, its name: the Dust Bowl.

 Dust was dirty, for sure, but it could also be deadly. In the 1930s, hundreds, or perhaps thousands, of people perished from “dust pneumonia” caused by dust clogging their lungs. And dust is worrisome in other ways—it can set off asthma attacks, and it can pick up and carry diseases and pollutants. “There’s public health costs” when it comes to dust, Okin notes.

 The Dust Bowl inhabitants didn’t know at the time, but the dust was also making the drought worse, Seager and his colleagues would discover decades later. All that dust kicked up into the atmosphere reduced the amount of energy from the sun that could reach the surface. That energy does more than simply provide heat; it also drives the planet’s water cycle. With less energy, there was less evaporation and less water making it back up into the atmosphere. With fewer plants around to bring water from the ground into the air—a process called evapotranspiration—the water cycle was completely out of whack, temperatures rose and the area of the drought expanded. “The dust storms themselves prevented more precipitation from happening,” Seager says.

 The dust storms finally began to let up near the end of the 1930s, when more regular rains returned and the efforts of the federal government began to take effect. In 1935, the Black Sunday dust storm had driven east to Washington, D.C., bringing its gloom to the nation’s capitol just as the U.S. Congress was considering soil conservation legislation. Less than two weeks later, they passed the law creating the Soil Conservation Service, a government agency devoted to helping farmers combat the factors that contributed to the Dust Bowl in the first place.

 Because most farms at the time were small, farmers had been unable, or unwilling, to implement techniques to prevent erosion, such as terracing and contour plowing. Even if they had the funds for such projects, they could still get inundated with dust from farms upwind. But with emergency funding from the Soil Conservation Service, farmers could afford to implement the necessary measures. The government stepped up in other ways, too, planting “shelterbelts” of trees to lessen the winds as they blew across the vast plains, buying up marginal lands that were unsuitable for cultivation and requiring sustainable grazing practices.

 As the 20th century progressed, farming changed. “They irrigated in the 1950s,” Seager notes. “Now, when droughts come along, you can try to compensate for a lack of precipitation by pumping up ground water and irrigating.” 

 The consolidation of farms—from 1950 to 1970, average farm size doubled—enabled more conservation. And the invention of no-till farming further preserved soil. Plowing the land had been necessary to aerate soil, free up nutrients and get rid of weeds, but it also led to erosion and dust. No-till farming avoids that damage by planting directly on the remains of the previous season’s crops. (The technique is not entirely conservation friendly, however, as it requires chemicals to kill weeds.) The development of drought-tolerant crops now promises even greater ability to survive a more arid climate.

 The United States weathered severe droughts in the 1950s and late 1980s, without the damage seen in the Dust Bowl years due to conservation efforts and the changes in farming techniques. But similar conditions could return, some scientists have noted. “In a certain sense, we’re in a dust bowl,” Okin says. “If the next three years or five years [are] a drought, even if it’s not that bad, if we start seeing continual dust storms, then that would be really no different from what was the Dust Bowl.”

 But even if the current drought ends quickly, climatologists are predicting that anthropogenic climate change will bring even drier times in the future for many of these states. “We expect that the southern part of the United States and south Plains get drier over the current century,” Seager says, “so in places like Texas, New Mexico, Arizona, yes, you would expect events like this to become more likely.”

 And some farmers may soon be unable to irrigate their way through a drought. The Ogallala Aquifer lies beneath eight Great Plains states and feeds about 27 percent of the nation’s farmland. Some aquifers are regularly recharged with water from rain or snow, but not the Ogallala. If completely drained, the aquifer would take 6,000 years of rain to fill back up. Decades of irrigation, development and industry have taken their toll on this important water source. Farmers started noticing in the 1990s that the water in their wells was dropping. That drawdown has continued, and water levels have dropped by as much as several feet per year in some places. Just when the aquifer will become unusable is difficult to predict, but irrigated agriculture in the region may become near impossible within decades. 

And now conservation—one of the great legacies of the Dust Bowl—is becoming a target in an era of government cuts. Critics find the policies difficult to justify, for example, paying farmers not to plant and to instead leave land covered with protective, native vegetation.

 Scientists can’t predict whether another Dust Bowl will happen, but they see worrisome signs not only in the Great Plains but in other semi-arid regions across the world, such as northern China where frequent dust storms sweep air full of dirt and industrial chemicals from polluted cities into Japan and Korea. “On a regional level, human activities matter a lot,” Okin says.

That’s the big lesson from the Dust Bowl—that it’s possible for humans to take a natural disaster and make it worse for the environment and for themselves. “We’d better be very careful about how the land is treated,” Seager says, “to make sure that we don’t get remotely close to triggering that kind of feedback.”