A new scientific paper published in Weather and Climate Extremes (Elsevier) presents a breakthrough in understanding flash droughts – droughts that develop rapidly within days or weeks. Conducted by researchers from Politecnico di Milano and the Joint Research Centre of the European Commission, both partners in SEED-FD, together with partners in Italy and Argentina, the work introduces a new index that opens the way to forecasting such extreme events.
The Challenge of Flash Droughts
While many droughts evolve gradually, flash droughts strike with sudden intensity. Their rapid onset can disrupt food production, strain water systems, and jeopardize livelihoods across entire regions. Communities often find themselves unprepared, as there is little opportunity to activate protective measures before the impacts take hold.
Operationally, flash droughts are difficult to predict, as early warning systems usually rely on near-real-time monitoring – and such data are only accessible with a delay of several days. SEED-FD aims to close this gap by developing a forecast product specifically for flash droughts to better anticipate a wider range of extreme weather events.
A New Index for Early Warning
The publication introduces the Initial Development Rate (IDR₃), a novel index that represents how quickly droughts intensify during their first 30 days. Traditional drought metrics typically focus on severity or duration. IDR₃ adds a new perspective: the speed of development.
By analyzing decades of soil moisture data from the Copernicus Emergency Management Service alongside satellite observations, researchers showed that IDR₃ reliably distinguishes between slow-evolving and fast-intensifying droughts. This makes the index highly valuable for integration into operational early warning systems.
Studying Flash Droughts in South America
To demonstrate the practical relevance of IDR₃, the study analyzed two major flash droughts in the La Plata river basin: one in 2011 and another in 2017/2018. This basin covers parts of Brazil, Argentina, Paraguay, and Uruguay – and also includes the Paraná river basin, which is one of SEED-FD’s use case regions.
Image 1: Maps of the Initial Development Rate (IDR₃) for two droughts in the La Plata basin (2011 and 2017-2018). Red areas indicate fast-developing flash drought conditions, while yellow tones show slower development. The maps are based on soil moisture data from LISFLOOD (the hydrological model behind the Copernicus Emergency Management Service) and ASCAT (satellite-based soil moisture data). Source: Cammalleri et al. (2025), Weather and Climate Extremes, Elsevier. https://doi.org/10.1016/j.wace.2025.100800 – CC BY-NC-ND 4.0
The 2011 event developed especially rapidly in parts of Paraguay, Brazil, and Argentina, while the 2017/2018 drought spread more slowly across a wider area. Both events had severe impacts on agriculture, with billions of dollars in crop losses. Aside from small variations between the two soil moisture datasets, the results were largely consistent in showing where the droughts occurred and how quickly they developed.
Beyond these two cases, the researchers also tested IDR₃ on a global scale. They examined how the index behaves across different seasons and explored environmental factors, such as climate variability and land conditions, that influence how quickly droughts can spread. This broader perspective demonstrates the versatility of the index and its potential to improve drought forecasting in diverse regions worldwide.
Impacts of Making Flash Droughts Predictable
The research shows that flash droughts can be distinguished from slower events within just the first month of development. The new index highlights their speed of intensification, offering a valuable step towards forecasting these events before they reach their full intensity.
For people on the ground, this added foresight can be decisive. Farmers may adjust irrigation or planting schedules, while water managers can prepare reservoirs and distribution systems in advance. Governments and local authorities gain valuable time to activate emergency plans, coordinate relief, and support vulnerable communities. Early warnings help transform flash droughts from sudden shocks into anticipated risks, reducing damage to livelihoods and economies.
Conclusion and Outlook
The new publication represents an important step towards improving the global detection and forecasting of extreme weather events. By introducing a new index based on short time spans that advances the ability to forecast flash droughts, it strengthens SEED-FD’s efforts to expand the Copernicus Emergency Management Service (CEMS) early warning system to cover a broader spectrum of natural hazards.
Integrating these results along with other findings from SEED-FD, the new prototype of the enhanced CEMS EWS will be tested more extensively in the further course of the current validation phase. The aim is to ensure global applicability and to assess how far the system is improved through SEED-FD research.
The full article, Beyond simple flash drought detection: An operational index to analyse the development speed of droughts at global scale, is available here.
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