Last night, the second part of Ken Burns' latest documentary premiered on PBS. "The Dust Bowl" tells the story of the people who farmed the Great Plains in the 1920s and 1930s; many stayed on once the ground dried up and dust storms became commonplace, while others moved west to find work.I knew the story of the Dust Bowl before watching the documentary, but had never heard it described as an ecological disaster, which of course it was. Plowing up the native grasses and planting wheat decimated the land, and once the drought began there was nothing to stop the soil erosion and the dust storms began.The two-part documentary focuses on the conditions leading up to the Dust Bowl of the 1930s, and on the dust storms themselves. But then, for a few minutes at the end, Burns takes a look at the aftermath: now, the Great Plains can once again sustain crops, and farmers have begun irrigation techniques.From The Dust Bowl website: But now, instead of looking to the skies for rain, many farmers began looking beneath the soil, where they believed a more reliable – and irresistible -- supply of water could be found: the vast Ogallala aquifer, a huge underground reservoir stretching from Nebraska to north Texas, filled with water that had seeped down for centuries after the last Ice Age. With new technology and cheap power from recent natural gas discoveries in the southern Plains, farmers could pump the ancient water up, irrigate their land, and grow other crops like feed corn for cattle and pigs, which requires even more moisture than wheat. Writer Timothy Egan calls the Dust Bowl "a classic tale of human beings pushing too hard against nature, and nature pushing back."The film asks the question "Could this Dust Bowl happen again?" and the answer seems to be "yes." Now the region is dependent on crops that need water, and experts say the water in the Ogallala aquifer will run out in the next few decades. The end of the documentary foreshadows what could be coming as the climate of the United States changes, and droughts once again decimate the crops: a second Dust Bowl.If you missed the documentary, you can watch parts of it on PBS' website.