The warming climate is causing soils to lose their moisture more quickly, resulting in damaging, rapid-onset droughts
Climate change is leading to more frequent “flash droughts”, which take just a few weeks to materialise and can send shock waves through affected ecosystems.
Almost three-quarters of the world has seen a rise in these sudden dry spells over the past 64 years, according to modelling by Xing Yuan at Nanjing University of Information Science and Technology in China and his colleagues.
As climate change advances, almost all the world’s landmasses will be affected by more frequent flash droughts that take hold faster, with Europe a particular hotspot, says Yuan.
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These events usually last for between 30 and 45 days, whereas slow-onset droughts tend to take several weeks or months to appear and last for 40 to 60 days. The increase in flash versions is due to the warming climate, he says.
“Under global warming, the climate’s variability has increased. So, you’ve got more extremes: you can get very heavy precipitation, but you can also get very dry conditions,” says Yuan.
Warmer air temperatures also mean water evaporates from soil more quickly, bringing on a drought state sooner, he adds.
“These two factors provide a driver to increase the speed of the drought onset,” says Yuan.
Although the work suggests that the incidence of flash droughts is increasing significantly around the world, it doesn’t provide data demonstrating the pace of change. But Yuan says the proportion of dry periods that are flash droughts could increase by 15 to 20 per cent between 2050 and 2100, compared with between 1950 and 2000, depending on how quickly the climate warms.
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On a global scale, this would have worrying implications. As Yuan points out, existing drought monitoring systems aren’t designed to spot incoming flash droughts, leaving regions with very little warning before one hits.
More accurate forecasts would help water companies and farmers conserve water in advance, to protect supplies for the public and food production, he says.
Wildlife and plant life may also struggle to adapt to rapid-onset drought, warns Yuan. “For the traditional drought, the vegetation is adapting to the drought event,” he says. But if the drought occurs faster, it isn’t known if the ecosystem will have enough time to adapt, he says.
Journal reference: ScienceDOI: 10.1126/science.abn6301