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 country," but historically speaking it was a "mere dry spell" compared to some past 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 TomDispatch 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."
As you read deBuys's latest post, it's worth remembering that even the greatest hydraulic engineers have their limits when the water dries up. When the Anglo farmers of the Phoenix Basin first started using the local rivers, they found themselves "reopening the canals the Hohokam had left behind." Who knows what monumental works we, too, might someday abandon? Phoenix, anyone? Tom
Phoenix in the Climate Crosshairs
We Are Long Past Coal Mine Canaries
By William deBuys
If cities were stocks, you'd want to short Phoenix.
Of course, it's an easy city to pick on. The nation's 13th largest metropolitan area (nudging out Detroit) crams 4.3 million people into a low bowl in a hot desert, where horrific heat waves and windstorms visit it regularly. It snuggles next to the nation's largest nuclear plant and, having exhausted local sources, it depends on an improbable infrastructure to suck water from the distant (and dwindling) Colorado River.
In Phoenix, you don't ask: What could go wrong? You ask: What couldn't?
And that's the point, really. Phoenix's multiple vulnerabilities, which are plenty daunting taken one by one, have the capacity to magnify one another, like compounding illnesses. In this regard, it's a quintessentially modern city, a pyramid of complexities requiring large energy inputs to keep the whole apparatus humming. The urban disasters of our time -- New Orleans hit by Katrina, New York City swamped by Sandy -- may arise from single storms, but the damage they do is the result of a chain reaction of failures -- grids going down, levees failing, back-up systems not backing up. As you might expect, academics have come up with a name for such breakdowns: infrastructure failure interdependencies. You wouldn't want to use it in a poem, but it does catch an emerging theme of our time.
Phoenix's pyramid of complexities looks shakier than most because it stands squarely in the crosshairs of climate change. The area, like much of the rest of the American Southwest, is already hot and dry; it's getting ever hotter and drier, and is increasingly battered by powerful storms. Sandy and Katrina previewed how coastal cities can expect to fare as seas rise and storms strengthen. Phoenix pulls back the curtain on the future of inland empires. If you want a taste of the brutal new climate to come, the place to look is where that climate is already harsh, and growing more so -- the aptly named Valley of the Sun.
In Phoenix, it's the convergence of heat, drought, and violent winds, interacting and amplifying each other that you worry about. Generally speaking, in contemporary society, nothing that matters happens for just one reason, and in Phoenix there are all too many "reasons" primed to collaborate and produce big problems, with climate change foremost among them, juicing up the heat, the drought, and the wind to ever greater extremes, like so many sluggers on steroids. Notably, each of these nemeses, in its own way, has the potential to undermine the sine qua non of modern urban life, the electrical grid, which in Phoenix merits special attention.
If, in summer, the grid there fails on a large scale and for a significant period of time, the fallout will make the consequences of Superstorm Sandy look mild. Sure, people will hunt madly for power outlets to charge their cellphones and struggle to keep their milk fresh, but communications and food refrigeration will not top their list of priorities. Phoenix is an air-conditioned city. If the power goes out, people fry.
In the summer of 2003, a heat wave swept Europe and killed 70,000 people. The temperature in London touched 100 degrees Fahrenheit for the first time since records had been kept, and in portions of France the mercury climbed as high as 104 -F. Those temperatures, however, are child's play in Phoenix, where readings commonly exceed 100 -F for more than 100 days a year. In 2011, the city set a new record for days over 110 -F: there were 33 of them, more than a month of spectacularly superheated days ushering in a new era.
In Flight From the Sun
It goes without saying that Phoenix's desert setting is hot by nature, but we've made it hotter. The city is a masonry world, with asphalt and concrete everywhere. The hard, heavy materials of its buildings and roads absorb heat efficiently and give it back more slowly than the naked land. In a sense, the whole city is really a thermal battery, soaking up energy by day and releasing it at night. The result is an "urban heat island," which, in turn, prevents the cool of the desert night from providing much relief.