Background Global climate change is challenging the traditional paradigm of slow-onset drought, fostering a shift towards “flash droughts”—extreme events with rapid development and severe destructive potential. Their sudden onset provides minimal time for response, amplifying their ecological and socioeconomic impacts and creating an urgent need to understand their mechanisms and patterns. This paper addresses this challenge by systematically reviewing and synthesizing the current scientific understanding of flash droughts, their drivers, and impacts under global change.
Methods This paper first traces the evolution of the flash drought concept, clarifying the current definition framework, which centers on three core elements. It further deconstructs the physical mechanisms, demonstrating how global change non-linearly amplifies flash drought risk through synergistic interactions across the atmosphere, ocean, and land, and examines the core scientific questions within this framework.
Results 1) A unifying definition framework distinguishes flash droughts through three criteria: a rapid onset, an obvious moisture deficit (e.g., soil moisture below the 20th percentile), and substantial impacts on one or more sectors. In contrast to traditional droughts, flash droughts develop over weeks instead of months, are driven by both precipitation deficits and high evaporative demand, and exhibit lower predictability. 2) Observational and modeling evidence indicates a significant acceleration in the global intensification rate of droughts over recent decades, with future scenarios projecting a continued rise in the frequency and intensity of flash drought events. A notable global transition from slow-onset to flash droughts is already evident across 74% of regions. Under high-emission scenarios, the annual risk to croplands is projected to rise significantly in North America and Europe by 2100, and the frequency of flash droughts in China is expected to increase across more than 65% of the land area. 3) The formation of flash droughts is driven by a severe surface water imbalance—a sudden precipitation deficit combined with high evaporative demand. This is amplified by large-scale oceanic anomalies (e.g., El Niño–Southern Oscillation, ENSO), reinforcing land-atmosphere feedbacks that accelerate drying, and changes in land surface conditions like earlier snowmelt. 4) Impacts of flash drought are rapid, severe, and cascading, encompassing major agricultural losses, sharp declines in ecosystem productivity, increased wildfire risk, and reductions in water resources.
Conclusions This paper confirms that global change is a primary driver and amplifier of flash drought risk, catalyzing a global shift toward these rapid-onset events. These findings underscore the inadequacy of traditional drought management frameworks, and highlight an urgent need to: 1) Develop high-resolution, multi-indicator integrated monitoring and early warning systems; 2) Overcome forecasting limitations at sub-seasonal to seasonal timescales; and 3) Establish comprehensive risk governance frameworks from local to global scales. Ultimately, this paper aims to advance scientific understanding of flash droughts, strengthen disaster risk reduction capacities, and provide a scientific basis for climate-related policymaking.
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