‘Flash droughts’ coming on faster, global study shows

Just like floods, quick-dryers come quickly – drying out the soil in a few days to weeks. These events can wipe out crops and cause huge financial losses. And according to researchers, the speed with which they dry out the landscape has increased.

Researchers at the University of Texas at Austin, Hong Kong Polytechnic University and Texas Tech University found that although the number of rapid droughts has been stable over the past two decades, more are coming faster. Globally, the fastest drought that comes fastest – leading to drought in just five days – has increased by about 3-19%. And in places that are particularly vulnerable to rapid droughts – such as South Asia, Southeast Asia and central North America – the increase is about 22-59%.

Rising global temperatures are probably behind the faster debut, said co-author and professor at UT Jackson School Zong-Liang Yang, who added that the results of the study underscore the importance of understanding rapid droughts and preparing for their effects.

“Every year we see record-breaking warming episodes, and it’s a good precursor to these rapid droughts,” he said. “Hope and purpose [of this research] is to minimize the harmful effects. “

The research was published in Nature communication. The study was led by PhD student Yamin Qing and Professor Shuo Wang, both from Hong Kong Polytechnic University.

Rapid drought is relatively new to science, and the development of remote sensing technology in recent decades has helped to reveal cases of rapid drought. This acts as a sign of the onset of a rapid drought and may cause the drought to appear out of the blue.

As the name suggests, drought is short-lived, usually only a few weeks or months. However, when they occur during critical growing seasons, they can cause disasters. For example, in the summer of 2012, a rapid drought in the central United States caused the corn crop to wither, leading to an estimated $ 35.7 billion in losses.

In this study, the researchers analyzed global hydroclimate data sets that use satellite soil moisture measurements to capture a global picture of rapid drought and how it has changed over the past 21 years. The data showed that about 34–46% of the rapid droughts occurred in about five days. The rest show up within a month, with more than 70% developing in half a month or less.

When they examined the drought over time, they noticed that the fast dryers occurred faster.

The study also revealed the importance of humidity and varying weather patterns, with rapid droughts becoming more likely when there is a transition from humid to dry conditions. This causes regions that undergo seasonal fluctuations in humidity – such as Southeast Asia, the Amazon Basin and the US East Coast and Gulf Coast – to explode in drought.

“We should pay close attention to the vulnerable regions with a high probability of simultaneous ground drought and air drought,” said Wang.

Mark Svoboda, director of the National Drought Mitigation Center and author of the term “flash drought”, said that advances in drought detection technology and modeling tools – such as those used in this study – have led to increased awareness of the effects and effects of rapid drought. He said the next big step is to translate this knowledge into on-site planning.

“You can go back and see how the drought developed in 2012 and then compare it with how that tool did,” says Svoboda, who was not part of the study. “We really have the conditions 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.


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