Study finds flash droughts are becoming more common in Australia
As global temperatures rise, a recent study highlights the increasing frequency of flash droughts, especially notable in regions like Australia. These insights highlight the importance of gaining a deeper understanding of the drivers behind flash droughts to enhance preparedness and mitigate the socio-economic and environmental consequences of rapid and intense drought events.
In a study, published in the open access journal Climate, researchers from the University of Technology Sydney investigate a recent flash drought in the Upper Hunter Valley region located in New South Wales (NSW), Eastern Australia. Employing various machine learning techniques alongside detailed climate models, the researchers aimed to identify the key climate drivers behind flash droughts, enhancing future prediction capabilities.
Flash droughts manifest abruptly and intensify rapidly. They are characterised by sudden decreases in rainfall accompanied by above-average temperatures. Described by the USA National Oceanic and Atmospheric Administration (NOAA) as rapidly developing droughts, flash droughts often leave regions in drought conditions within a short span of below-average rainfall, typically lasting for weeks or months.
These sudden droughts can have devastating economic, social and environmental impacts. Particularly vulnerable are agricultural regions reliant on consistent rainfall within river catchments, such as the Upper Hunter region, renowned for its agricultural productivity - a focal point for the researchers.
Between May to October in 2023, flash droughts affected the Upper Hunter region. Of particular interest to the researchers was the emergence of this flash drought event, despite the region being declared drought-free just one month earlier.
“At that stage, almost nowhere in NSW showed any sign of an impending drought,” explain the authors of the study.
The 2023 flash drought in the Upper Hunter had a significant impact on agricultural production in the region, primarily due to the region’s reliance on water from rivers.
“Low rainfall in river catchments means less water for crops and pasture. It also dries up drinking water supplies,” says the authors of the study.
Employing machine learning techniques, the researchers analysed rainfall variability in the Upper Hunter region using data spanning from 1963 to 2022. By focusing on the May to October periods each year, coinciding with the recent flash drought, they sought to identify key patterns and attributes crucial for predicting flash drought intensification.
“We found the dominant driver of the flash drought was global warming, modulated by the phases of the three major climate drivers in our region, the El Niño Southern Oscillation, Indian Ocean Dipole and the Southern Annular Mode,” explain the authors of the study.
The researchers detail how this interplay caused rainfall variability to significantly increase, creating an atmospheric environment conducive to flash droughts across southeast Australia.
Notably, the researchers mention another area of interest outside of the Upper Hunter Valley region study site which was also affected by flash droughts earlier this year. This region, located in the western parts of Victoria, also fit the global warming patterns observed within this study.
“The pattern of the 2024 flash drought in Victoria typifies the increasing trend under global warming of long dry periods, interspersed by short, heavy rainfall events,” add the authors of the study.
The researchers suggest that flash droughts are likely to become more common due to rising temperatures, drier conditions, and decreasing relative humidity across different regions in Australia and globally.
If you’re interested in learning more about this research, you can access the paper published in Climate here: https://shorturl.at/qtHO5