Last year was the warmest on record in California, its driest spell for more than 400 years but a new study says that’s nothing compared to what’s in store.
In a 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, may face unprecedented drought conditions, unseen in the past 1,000 years.
In about 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 the climate change.
“Nearly every year is going to be dry toward the end of the 21st century,” said Ben Cook from Nasa’s Goddard Institute for Space Studies.
The longer period of dry conditions could devastate the US’s agriculture, decimating both crops and cattle herds, creating huge food shortage and sending food prices sky-rocketing, he said.
The impact of it would be felt by more than 60 million people from San Diego to San Antonio and from Oakland to Omaha, who depend on fast depleting water resources, he cautioned. It would be more pronouced in desert cities such as Las Vegas and Phoenix.
The region experienced similar drought in the 14th century called the “Medieval Climate Anomaly” that led to the demise of some early civilizations in the Americas. The next phase may begin in 2050 and last for over five decades, they said.
Dr Jason Smerdon, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory and co-author of the study, said: “We are the first to do this kind of quantitative comparison between the projections and the distant past, and the story is a bit bleak.”
The mega-drought would affect Nevada, Utah, Colorado, New Mexico, Texas, Oklahoma, Kansas, Nebraska, South Dakota, Iowa, Minnesota, Missouri, Arkansas and Louisiana.
The study was based on the rate of rising emissions and on complex climate simulations produced by 17 different computer models, which all broadly agreed on the results.
Ben Cook said, “The droughts people do know about, like the 1930s ‘dustbowl’ or the 1950s drought or even the ongoing drought in California and the south-west today – these are all naturally occurring droughts that are expected to last only a few years or perhaps a decade. Imagine instead the current California drought going on for another 20 years.”
Cook and Smerdon’s co-author Toby Ault, from the Department of Earth and Atmospheric Sciences at Cornell, said climate change would be the main cause behind such a mega-drought.
Presenting the findings during the annual American Association for the Advancement of Science (AAAS) conference in San Jose, California, Ault said: “We’re not necessarily locked into these high levels of mega-drought risk, if we take actions to slow the effects of rising greenhouse gases on global temperatures.”
Perhaps, the recently sent DSCOVR satellite should provide more indepth data about the possibility of the mega-drought now.
For several months, California has been in a state of “exceptional drought.” The state’s usually verdant Central Valley produces one-sixth of the U.S.’s crops.
Image Credit: White House via Wikimedia Commons.