Via The Independent: In the eye of a mega-drought: Researchers warn US should prepare for 'unprecedented drought conditions' unlike anything in past 1,000 years . Excerpt and then a comment:
Since the turn of this century, the US south-west has spent more than a decade in drought. Last year was the warmest on record in California, which is in the middle of its driest spell for more than 400 years. But according to a new scientific study, that’s nothing compared to what comes next.
In the paper, published by the journal Science Advances, researchers from Nasa and Columbia and Cornell universities warn that a vast swathe of the US, including the south-west states and the central plains, should prepare for “unprecedented drought conditions” unlike anything in the past 1,000 years.
Within 35 years, the region’s millennia-long natural cycle of droughts and occasional rainfall is likely to bring an end to the relative dampness of the last century. The effects of that drying, the scientists warn, would be exacerbated by man-made climate change.
“Nearly every year is going to be dry toward the end of the 21st century, compared with what we think of as normal conditions now,” said Ben Cook from Nasa’s Goddard Institute for Space Studies, the lead author of the study. “We’re going to have to think about a much drier future in western North America.”
The long-term dry conditions could devastate the region’s agricultural capability, decimating both crops and cattle herds, and sending some food prices sky-rocketing. It would directly affect more than 60 million people from San Diego to San Antonio and from Oakland to Omaha, who depend on increasingly scant water resources and on infrastructure designed during an abnormally moist 20th century.
The scientists said the effects of a mega-drought, which would be especially pronounced in desert cities such as Las Vegas and Phoenix, should be considered a slow-motion natural disaster, of a piece with earthquakes or hurricanes.
Data discovered in tree rings shows that between the ninth and the 14th centuries, the region also endured lengthy periods of intense drought, an era referred to by paleoclimatologists as the “Medieval Climate Anomaly”, which is believed to have hastened the demise of some early civilisations. But decades of dry conditions, beginning in about 2050, could be even worse, the study predicts.
A few years ago I wrote a review of a book about the Anasazi, who built a remarkable society in what is now the American Southwest. And like everyone of my war-baby generation, I read Steinbeck's The Grapes of Wrath, about the Joads, Oklahoma farmers who fled the 1930s Middle West Dust Bowl for the dubious haven of California.