A global study says sudden droughts are happening faster

Like sudden floods, sudden droughts occur quickly, drying up the earth in a matter of days or even weeks. These events can destroy crops and cause significant economic losses. And, according to scientists, the speed of drying the landscape has increased.

Researchers from the University of Texas at Austin, Hong Kong Polytechnic University and Texas Tech University have found that while the number of sudden droughts has remained stable over the past two decades, more are happening faster. The world’s fastest-growing droughts, in just five days, have risen by about 3 to 19 percent. In areas most vulnerable to severe droughts, such as South Asia, Southeast Asia and Central North America, the increase is around 22-59 percent.

Rising global temperatures are likely to be to blame for the faster start, said co-author and UT Jackson School professor Zong-Liang Yang, who added that the study shows how important it is to understand sudden droughts and prepare for their consequences.

“We see record warming attacks every year, and it’s a good precursor to those sudden droughts,” he said. “It simply came to our notice then [of this research] is to reduce the negative effects. »

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

Sudden droughts are relatively new to science, and advances in remote-sensing technology over the past two decades have helped uncover cases of rapid soil drying. This is a signal of the onset of a sudden drought and can cause drought conditions unexpectedly.

As the name suggests, sudden droughts are short-lived, usually lasting only a few weeks or months. However, when they occur during critical periods of growth, they can cause disaster. For example, in 2012. In the summer of 2007, a sudden drought in the central part of the United States caused a corn harvest of 35.7 billion euros.

In this study, the researchers analyzed global climatic data sets that use satellite measurements of soil moisture to capture a global picture of the sudden drought and its evolution over the past 21 years. Data show that about 34-46% of sudden droughts occur in about five days. The rest appear in a month, with more than 70% developing in half a month or less.

Looking at droughts over time, they noticed that sudden droughts occurred faster.

The study also revealed the importance of humidity and changing weather conditions as sudden droughts become more likely when transitioning from wet to dry conditions. As a result, regions with seasonal changes in humidity, such as Southeast Asia, the Amazon Basin and the east coast of the United States, and the Gulf Coast, are droughts.

“We need to pay special attention to vulnerable regions with a high risk of soil drought and atmospheric drought,” Wang said.

Mark Svoboda, director of the National Drought Reduction Center and pioneer of the term “lightning drought,” said advances in drought-sensing technology and modeling tools such as those used in this study have increased awareness of the effects and effects of drought. sudden drought. He said the next big step is to turn that knowledge into planning on the spot.

“You can go back and watch this drought develop in 2012 and then compare it to the evolution of this tool,” said Svoboda, who did not participate in the study. “We really have a well-prepared soil so that we can better monitor these droughts. »

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

Godfrey Kemp

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