The Texas drought is just the worst on record in recent times. The dendrochronology — tree ring analysis — for the region shows that decade long droughts are not unusual in that region. Paire that with global warming, and…
Richard Parker, As Texas Dries Out, Life Falters and Fades
Generally, droughts in the Southwest are caused by La Niña, the weather pattern involving cooling of waters in the Pacific, which pushes warm, dry air inland, shifting the rains away from Texas, New Mexico and Arizona. In Texas the worst drought, known as the Drought of Record, parched the state from the late 1940s to the late 1950s, with catastrophic consequences for land, livestock and people. Yet that drought was the longest only since rain gauges have been used to keep records — a practice that began in 1895.
In fact, Texas has long been stalked by megadroughts, events that can last 30, even 40 years. The story is told within the trunks of the bald cypress that line the creek and riverbeds of central Texas. Using the science of dendrochronology, researchers from Texas and Arkansas sampled nearly 300 trunk-core samples, creating a record of tree rings stretching back before Columbus landed in the Americas. One tree, still living, was but a sapling in 1426.
The record shows that in the 1700s and early 1800s, before American settlement and even extensive Spanish and Mexican settlement, several dry stretches were longer than the Drought of Record. The driest 10 years were 1716 through 1725, and the worst 20 years were 1697 through 1716. There have been numerous 30- and 40-year droughts. The worst gripped Texas and Mexico for nearly a half-century, from 1450 to 1489.
But the future, sadly, is likely to be worse than the past. “Texas is going to get hotter and drier,” said Malcolm Cleaveland, a professor at the University of Arkansas who led the researchers. Indeed, rainfall modeling shows that rising temperatures and more arid conditions over the last few decades are likely to increase in the 21st century.
According to a paper published in Science in 2007, “Droughts will become the new climatology of the American Southwest within a time frame of years to decades.” Rain will become more rare and it will evaporate more quickly, making the megadroughts of old look like periodic dry spells. And it will be in part thanks to increased carbon emissions, a fact that Texas will have a hard time confronting.