Tomgram: William deBuys, Exodus from Phoenix

We're not the first people on the planet ever to experience climate stress. In the overheating, increasingly parched American Southwest, which has been experiencing rising temperatures, spreading drought conditions, and record wildfires, there is an ancient history of staggering mega droughts, events far worse than the infamous dust bowl of the 1930s, the seven year drought that devastated America's prairie lands. That may have been the worst prolonged environmental disaster recorded for the count, but historically speaking, it was a mere dry spell compared to some of the mega droughts that lasted centuries to millennia. Such events even happened in human history, including an almost century long southwestern dry spell in the second century AD, and a drought that was at least decades long in the twelfth century. These were all events driven by natural climate variation. Climate change adds a human factor to the equation in a region already naturally dry, and short on water. It ups the odds of bad events happening. In the coming century, how habitable will parts of the bustling desert Southwest turn out to be? Already, in the face of heat and drought, small numbers of people from small towns in the region are leaving. And this, too, has happened before. There are sobering previous examples of what it means, when extreme climate stress hits this area. Chaco Canyon was abandoned by its native population during that twelfth century drought, and 150 years later, the Hohokam native culture. of what is now central Arizona, whose waterworks in the dry lands of that area were major and impressive, also abandoned its lands, possibly due to drought, as Tom Dispatch regular William deBuys recounts in his recent book: A Great Aridness: Climate Change, and the Future of the American Southwest. At some point, he writes, Hohokam society passed a threshold, the number of able bodied workers it could muster was no longer sufficient to meet the challenge of rebuilding dams, when they washed out and cleaning canals, as they inevitably silted up. Eventually the hydraulic system collapsed, and the society that depended on it could no longer exist. The survivors turned their backs on their cities, and scattered into the vastness of the land, doing what they could to survive.