We should “prepare better” for future flash droughts

Most people are familiar with flash floods, those sudden deluges usually triggered by downpours that can level homes and infrastructure in an instant. Flash droughts are lesser-known phenomena in which dry spells can dry out crops in days or weeks, killing them and hitting economies.

That’s why we need to be more aware of flash droughts, as the speed at which they can appear out of nowhere and dry out landscapes has dramatically increased due to rising global temperatures, warns an international team of researchers from the United States . United States and Hong Kong. .

Scientists have found that the number of flash droughts has remained stable globally in this new century so far, but not their speed. The fastest ones create drought conditions in entire areas in just five days and have increased by 3 to 19%.

Meanwhile, in vulnerable areas particularly prone to sudden droughts, such as South Asia, Southeast Asia and central North America, the rate of increase was 22% to 59 %.

Although flash droughts last for shorter periods, they can still cause disasters, as happened in the central United States in the summer of 2012 when a flash drought resulted in nearly $36 billion losses by causing maize crops to wilt over large areas.


Devastating flash droughts expected

And such devastating episodes will become more likely in the coming years and decades as temperatures continue to rise, according to scientists who analyzed hydroclimate datasets with satellite measurements of soil moisture around the world. entire.

Experts have found that between 34% and 46% of flash droughts occurred in just five days, while most of the rest occurred within a month.

“Every year we see episodes of record warming, and that’s a good precursor to those flash droughts,” says Zong-Liang Yang, a professor at the University of Texas and co-author of the study. “Hope and Purpose [de esta investigación] is to minimize adverse effects.

Importantly, scientists say, changes in humidity and weather patterns make flash droughts more likely as conditions change from humid to arid, making regions that experience seasonal changes in humidity (such as Asia southeast, the Amazon basin, as well as the east coast and the Gulf). coast of the United States) particularly prone to flash droughts.

“We need to pay special attention to vulnerable regions with a high probability of simultaneous soil drought and atmospheric aridity,” said Shuo Wang, a professor at Hong Kong Polytechnic University.

On the plus side, advances in drought-sensing technology and modeling tools mean we can better prepare for flash droughts, says Mark Svoboda, director of the US National Drought Mitigation Center, which coined the term “flash drought.” “.

“You can go back and see the evolution of the drought in 2012 and then compare it to the evolution of this tool,” Svoboda said. “We really have the ground well prepared to do a better job of monitoring these droughts.”

By Daniel T. Cross. Articles in English

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