‘Flash droughts’ coming on faster, global study shows – Watts Up With That?

Peer-reviewed publication

UNIVERSITY OF TEXAS AT AUSTIN

IMAGE: DRY CORN STALKS IN IOWA DURING THE SUMMER 2012 FLASH DROUGHT, WHICH DESTROYED CROPS AND CAUSED $35.7 BILLION IN LOSSES. see more CREDIT: UNITED STATES DEPARTMENT OF AGRICULTURE

Like flash floods, flash droughts happen quickly, drying out the ground in a matter of days or weeks. These events can kill crops and cause huge economic losses. And according to scientists, the rate at which the landscape is drying has increased.

Researchers from the University of Texas at Austin, Hong Kong Polytechnic University, and Texas Tech University found that while the number of flash droughts has been stable over the past two decades, more of them are happening faster. Globally, the fastest-onset flash droughts (sending areas into drought conditions in just five days) have increased by between 3% and 19%. And in places that are especially prone to flash droughts, such as South Asia, Southeast Asia, and central North America, that increase is about 22% to 59%.

Rising global temperatures are likely behind the faster onset, said co-author and UT Jackson School professor Zong-Liang Yang, adding that the study results underscore the importance of understanding flash droughts and preparing for their effects. .

“Every year, we’re seeing episodes of record warming, and that’s a good precursor to these flash droughts,” he said. “Hope and purpose [of this research] is to minimize the detrimental effects.”

The research was published in nature communications. The study was led by doctoral student Yamin Qing and Professor Shuo Wang, both from the Hong Kong Polytechnic University.

Flash droughts are relatively new to science, with the advancement of remote sensing technology over the past two decades helping to reveal cases of rapidly drying soil. This serves as a telltale sign of the onset of a sudden drought and can make drought conditions seem unexpected.

As the name suggests, flash droughts are short-lived, typically lasting only a few weeks or months. But when they occur during critical growth periods, they can cause disaster. For example, in the summer of 2012, a flash drought in the central United States caused the corn crop to wilt, resulting in losses estimated at $35.7 billion.

In this study, scientists analyzed global hydroclimatic datasets that use satellite measurements of soil moisture to capture a global picture of flash drought and how it has changed over the past 21 years. The data showed that about 34% to 46% of flash droughts occurred within about five days. The rest emerge within a month, with over 70% developing in half a month or less.

When they examined droughts over time, they noticed that flash droughts occurred more quickly.

The study also revealed the importance of humidity and variable weather patterns, with sudden droughts becoming more likely when there is a change from wet to arid conditions. That makes regions that experience seasonal changes in humidity, such as Southeast Asia, the Amazon Basin, and the East Coast and Gulf Coast of the United States, drought hotspots.

“We should pay close attention to vulnerable regions with a high probability of simultaneous soil drought and atmospheric aridity,” Wang said.

Mark Svoboda, director of the National Drought Mitigation Center and originator of the term “flash drought,” said advances in drought-detection technology and modeling tools, such as those used in this study, have led to a increased awareness of the influence and impact of flash droughts. He said the next big step is translating this knowledge into planning on the ground.

“You can go back and see the evolution of the drought in 2012 and then compare it to the way that tool did it,” said Svoboda, who was not part of the study. “We really have the stage well set to do a better job of tracking these droughts.”

The study was funded by the National Natural Science Foundation of China and the Hong Kong Research Grants Council.


DOI

10.1038/s41467-022-28752-4

ARTICLE TITLE

Accelerated flash droughts induced by the joint influence of soil moisture depletion and atmospheric aridity

ARTICLE PUBLICATION DATE

3-Apr-2022

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