Flash drought is becoming increasingly frequent in Asia

In some Asian countries, says research, the frequency of sudden drought events has increased from 20 to 80 per cent in just two decades. But the phenomenon is now global

by Matteo Cavallito

 

“Flash droughts will expand and worsen in the future in South Asian countries, impacting water, agriculture, and energy sectors.” This is according to Ashok Mishra, a professor at Texas A&M University who, along with other researchers from different countries, has been examining in a study which factors play a key role in the origin of these phenomena. These particular events, scientists have long observed, are characterised by the onset of more extreme heat waves than those that occur with classic seasonal droughts.

The research, which involved scholars from the universities of Nanjing (in China), Peshawar (Pakistan), Jodpur (India) as well as Seoul National University of Science and Technology and the US Department of Agriculture’s (USDA) Center for Forested Wetlands Research, was published in the journal Communications Earth & Environment.

Flash drought getting worse with climate change

The study focused on the Asian case, the authors explain in a statement published by the University of Texas. But the results can be applied to other areas of the world that experience these sudden water shortages.

On this occasion, the researchers were able to analyse several aspects of these droughts, including the speed of onset, severity and duration. They also examined the role that atmospheric circulation – i.e. the mechanisms and processes active in the troposphere that help balance pressure and temperature differences – and climate change play in drought variability. Global warming, the authors explained, is expected to impact these drought events by making them more intense over time.

Frequency increases by up to 80%

In the course of the study, the authors explain, “We find that flash droughts are more common and intense in the crop season, especially in central India, western Pakistan, and eastern Afghanistan. They are caused by persistent atmospheric patterns that block moisture transport to South Asia.”

Moreover, “From the time series results, it is clear that the flash drought frequency for the spring-summer season increased significantly (at 95% confidence level) by about 20%, 40%, 60%, and 80% across Sri Lanka, Afghanistan, Pakistan, and India during the recent two decades (e.g., 2000-2020).”

Finally, the data “suggest that flash droughts will expand and worsen in the future, requiring adaptation measures for the water, agriculture, and energy sectors.” This will dictate, the authors conclude, the development of new tools for quantifying and forecasting these critical phenomena. By reducing water availability and soil moisture, the authors remind, these events create problems in several sectors and negatively impact ecosystem services.

Three quarters of the planet is already experiencing an increase in the phenomenon

The link between the increasing frequency of flash droughts and climate change has already been observed on other occasions. Last year, for example, in a study published in the journal Science, researchers led by National Natural Science Foundation of China professor Xing Yuan examined soil moisture data worldwide from 1951 to 2014 and calculated the rate of soil drying at the beginning and end of critical periods.

“Flash droughts have occurred frequently worldwide, with a rapid onset that challenges drought monitoring and forecasting capabilities,” the research said.

“Drought intensification rates have sped up over subseasonal time scales and that there has been a transition toward more flash droughts over 74% of the global regions identified by the Intergovernmental Panel on Climate Change Special Report on Extreme Events during the past 64 years.” In the future, moreover, “In the future, the transition is projected to expand to most land areas, with larger increases under higher-emission scenarios.”