A study published in Science of The Total Environment revealed that precipitation and potential evapotranspiration have increased synchronously across 34 major river basins worldwide from 1901 to 2021, and the dominance of potential evapotranspiration has resulted in a gradual intensification of meteorological drought.

"Meteorological drought is driven by changes in sea surface temperature, especially the El Niño–Southern Oscillation (ENSO) or other climate indices,” said Prof. DUAN Weili from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences, the corresponding author of this study.

To examine and compare meteorological droughts across 34 major global river basins, researchers employed a three-dimensional clustering algorithm that used the standardized precipitation evapotranspiration index over a 12-month period.

They found that 47% (16/34) of the basins showed a drying trend with prolonged durations of severe droughts, with the most severe drought event occurring in the Amazon Basin. Although drought events occurred frequently, more than half of them were identified as short-term droughts, lasting no more than three months.

Besides, researchers revealed that river basins in the tropical zone exhibit a pronounced trend towards heightened aridity, indicating a more severe drought situation, while those in the cold zone display a tendency towards increased wetness, suggesting a comparatively alleviated drought scenario.

This study offers insights into the attributes and underlying processes of meteorological droughts across various river basins worldwide.