For a week or more, reports have come in about new research showing a megadrought might have set in across the American southwest whose states have seen massive population growth in recent decades.
The American West is well on its way into one of the worst megadroughts on record, a new study warns, a dry period that could last for centuries, and spread from Oregon and Montana, through the Four Corners and into West Texas and northern Mexico.
Several other megadroughts, generally defined as dry periods that last 20 years or more, have been documented in the West going back to about 800 A.D. In the study, the researchers, using an extensive tree-ring history, compared recent climate data with conditions during the historic megadroughts.
They found that in this century, global warming is tipping the climate scale toward an unwelcome rerun, with dry conditions persisting far longer than at any other time since Europeans colonized and developed the region. The study was published online Thursday and appears in the April 17 issue of the journal Science.
Human-caused global warming is responsible for about half the severity of the emerging megadrought in western North America, said Jason Smerdon, a Columbia University climate researcher and a co-author of the new research.
"What we've identified as the culprit is the increased drying from the warming. The reality is that the drying from global warming is going to continue," he said. "We're on a trajectory in keeping with the worst megadroughts of the past millennia."
The regional drought caused by global warming is plain to see throughout the West in the United States. River flows are dwindling, reservoirs holding years worth of water supplies for cities and farms have emptied faster than a bathtub through an open drain, bugs and fires have destroyed millions of acres of forests, and dangerous dust storms are on the rise.
Smerdon said he's also concerned that the drought impacts are being underestimated because of an over-reliance on groundwater as a temporary buffer to the decline of river flows, and the drop of reservoir water levels. If you look at simultaneous droughts in North and South America, he said, you could also anticipate potential impacts to global food supply networks, as both regions are important for agricultural production.Eight years ago I posted about an article in Harper's magazine, "Broken Heartland, the Looming Collapse of Agriculture on the Great Plains." The author focused on the Ogallala or High Plains aquifer that underlies eight States comprising America's 'wheat belt.' Here are a few excerpts:
"Sprawling beneath eight states and more than 100 million acres, the Ogallala Aquifer is the kind of hydrological behemoth that lends itself to rhapsody and hubris. Ancient, epic, apparently endless, it is the largest subterranean water supply in the country, with an estimated capacity of a million-billion gallons, providing nearly a third of all American groundwater irrigation. If the aquifer were somehow raised to the surface, it would cover a larger area than any freshwater lake on Earth - by a factor of five."
"It wasn't until the 1940s, when a variety of new technologies coalesced on the plains, that large-scale irrigation sprang up for the first time - but from there, the transformation was quick. Within a decade thousands of wells were drilled, creating a spike in productivity as unprecedented as it was unsustainable. Land that had been marginal became dependable; land that was dependable became bountiful...
"No one worried about the aquifer. To farmers it seemed a bottomless reserve, generating the same outlandish volume no matter how many straws went in. Soon there were hundreds of thousands of wells producing the same reliable flow, year after year, without any evident stress.
"Then, during the early 1990s, farmers throughout the Great Plains began to notice a decline in their wells. Irrigation systems from the Dakotas to Texas dipped, and, in some places, have been abandoned entirely."
"...For complex reasons involving wind, weather and soil composition, the Ogallala does not recharge in the way one might expect. In fact, of the eight states above the aquifer, only Nebraska, with its sandhill dunes, is permeable enough to contribute any serious replenishment."Eight years ago the aquifer was down to its last 30 feet of water - in the lucky places. Further research found much of the dwindling remnant is also polluted, mainly from agricultural chemicals - fertilizers, pesticides, herbicides and such.
In 2014, NASA's amazing Grace satellites produced data showing that almost every major aquifer in the world was being rapidly depleted. NASA scientists warned that, within a decade, Earth's dwindling groundwater reserves could become weaponized by neighbouring nations or even be exploited by terrorists. The rumblings are being heard down the Nile valley where Egypt is threatening efforts by its upstream neighbours to dam and divert the river to their own purposes. Egypt has warned that, if dams are built, Egyptian warplanes may be sent to destroy them. In Asia, China, Pakistan and India are jostling to secure their access to the Himalayan headwaters. Three nations, all facing critical water shortages, all nuclear armed. What could possibly go wrong.
That's our world today and for many tomorrows. Pandemics, resource (oil) wars, resource (water) wars, food insecurity and so much more. This is no time for the weak-kneed.