Flash droughts are becoming more common; they can put crops and herds at risk; experts working on predicting them

A flash drought developed in a few weeks in 2019. (NASA Earth Observatory image)

As Earth warms, flash droughts they are becoming more common and can have a devastating ripple effect; understanding where and when they might occur could help farmers and ranchers plan, Jeff Basara and Jordan Christian report for The Conversation, a platform for journalism by academics: "In a new study, we found that the risk of flash droughts, which can develop in the span of a few weeks, is on pace to rise in every major agriculture region around the world in the coming decades. . . . In North America and Europe, cropland that had a 32% annual chance of a flash drought a few years ago could have as much as a 53% annual chance of a flash drought by the final decades of this century. The result would put food production, energy and water supplies under increasing pressure. . . . A flash drought in the Dakotas and Montana in 2017 caused $2.6 billion in agricultural damage in the U.S. alone."

What is a flash drought? "All droughts begin when precipitation stops. What's interesting about flash droughts is how fast they reinforce themselves, with some help from the warming climate," Basara and Christian explain. "When the weather is hot and dry, soil loses moisture rapidly. Dry air extracts moisture from the land, and rising temperatures can increase this 'evaporative demand.' The lack of rain during a flash drought can further contribute to the feedback processes. Under these conditions, crops and vegetation begin to die much more quickly than they do during typical long-term droughts."

Timing is crucial for agriculture. "In 2022, a [harvest-time] flash drought slowed barge traffic on the Mississippi River, which carries more than 90% of U.S. agriculture exports. . . . If a flash drought occurs at a critical point in the growing season, it could devastate an entire crop," Basara and Christian explain. "During the huge flash drought in 2012 in the central U.S., cattle ran out of forage and water became scarcer. If rain doesn't fall during the growing season for natural grasses, cattle don't have food, and ranchers may have little choice but to sell off part of their herds."

Improving weather predictions can help sectors better plan and prepare for flash droughts. "When we talk with farmers and ranchers, they want to know what the weather will look like over the next one to six months," the study's authors add. "We're tackling the challenge of monitoring and improving the lead time and accuracy of forecasts for flash droughts, as are other scientists. For example, the U.S. Drought Monitor has developed an experimental short-term map that can display developing flash droughts. As scientists learn more about the conditions that cause flash droughts and about their frequency and intensity, forecasts and monitoring tools will improve. . . . Nothing is getting easier for farmers and ranchers as global temperatures rise. Understanding the risk from flash droughts will help them."