Accelerating Flash Droughts in a Warming World
Xing Yuan
Institute of Atmospheric Physics, Chinese Academy of Sciences, China
Winning article: A global transition to flash droughts under climate change (Science, 2023)
“By understanding the drivers and impacts of flash droughts, we can develop actionable solutions to mitigate their effects and build resilience in a changing climate.”
Flash droughts, characterized by their rapid onset and intensification, have emerged as a critical challenge in the context of global climate change. Unlike slow-onset droughts, which are considered the typical presentation and develop over extended periods, flash droughts can transition normal conditions to severe droughts within weeks (Fig. 1). Despite their increasing frequency, it remains unclear whether they are becoming the new normal or if both slow and rapid onset droughts are on the rise.
Figure 1: Diagram of flash drought onset. Source: Prof Xing Yuan group.
The term "flash drought" was introduced in the early 21st century, but it was the devastating 2012 U.S. drought that truly brought the concept into the public and scientific spotlight. This drought, regarded as one of the most severe in the United States since the 1930s Dust Bowl, resulted in over $30 billion in economic losses. One of its most alarming characteristics was the rapid pace at which it intensified, with many regions transitioning from drought-free conditions to extreme drought within a single month. The severity and speed of this event were largely unexpected, and existing prediction models failed to anticipate its onset.
This sudden shift poses significant challenges for monitoring, forecasting, and preparedness efforts, making it difficult for both ecosystems and human societies to adapt in time. Our research aimed to address a critical gap in evidence to determine whether the speed of drought onset has accelerated globally, thereby informing efforts to prepare and protect ourselves from flash droughts.
We divided sub-seasonal droughts into flash droughts and slow droughts by onset speed (measured through the declining rate of soil moisture) and global distribution during the local growing season over the past 64 years. We then estimated global trends in the ratio of the number of flash droughts to total sub-seasonal droughts, and the global trends in the onset speed of sub-seasonal droughts. We concluded that these trends can be attributed to anthropogenic climate change, based on the sixth Coupled Model Intercomparison Project (CMIP6) climate model simulations. We also showed how these patterns vary over different IPCC SREX (Intergovernmental Panel on Climate Change Special Report on Extreme Events) regions.
Figure 2. Observed and simulated anomalies of global mean (A) flash drought ratio and (B) onset speed of sub-seasonal droughts. Future trends in (C) flash drought ratio and (D) onset speed of sub-seasonal droughts averaged over the IPCC SREX regions. Source: (Yuan et al., Science, 2023)
Our study, published in Science, provides conclusive evidence that drought onset speed has increased over sub-seasonal timescales, and there has been a transition toward more flash droughts across 74% of the global IPCC SREX regions over the past 64 years. This transition is primarily driven by anthropogenic climate change, particularly through the amplification of evapotranspiration anomalies and shifts in precipitation patterns. These findings underscore the urgency of adapting to faster-onset droughts in a warming world.
The impacts of flash droughts extend far beyond just water scarcity. Their rapid onset can exacerbate other extreme weather events, including mega-heatwaves and wildfires, leading to widespread ecosystem degradation. Vegetation suffers from sudden and severe moisture loss, resulting in reduced agricultural yields, damage to forests, and increased vulnerability to insect infestations and disease outbreaks. Additionally, flash droughts pose serious threats to global food security, as many of the world’s agricultural systems rely on consistent precipitation patterns. Rainfed crops, in particular, are highly susceptible to sudden moisture deficits, making flash droughts especially dangerous in regions already facing food insecurity. Beyond agriculture, these events also strain water supplies for human consumption and energy production, particularly in regions dependent on hydropower. The economic consequences of these disruptions are substantial, affecting industries, livelihoods, and national economies.
To reduce the impacts of flash droughts and enhance resilience for both natural and social systems, we should develop advanced early warning systems that utilize multisource datasets, including remote sensing, earth system models that consider ecological processes and human activities, and AI techniques to detect flash droughts in their early stages. In addition to improved forecasting, adaptation strategies must be implemented to build resilience against flash droughts. Agricultural practices that prioritize drought-resistant crops and precision irrigation techniques can help reduce vulnerability to sudden water stress. Sustainable water resource management strategies, such as expanding water storage infrastructure and optimizing reservoir operations, are also essential for mitigating the impacts of flash droughts.
At the policy level, governments must integrate flash drought risk into national climate adaptation plans, ensuring that response strategies are in place before these events occur. The increasing frequency and intensity of flash droughts highlight the urgent need for global climate mitigation efforts. While adaptation strategies can help societies cope with these events, reducing greenhouse gas emissions remains the most effective long-term solution for preventing their continued escalation. Research indicates that anthropogenic climate change is a primary driver of the shift from slow-evolving droughts to flash droughts, highlighting the direct link between rising global temperatures and increased drought risk. By limiting global warming through aggressive emission reductions, we can slow the transition toward more extreme and frequent flash droughts, reducing their overall impact on ecosystems and human communities.
Beyond their immediate consequences, flash droughts also have profound implications for planetary boundaries science. The planetary boundaries framework, which defines safe operating limits for key Earth system processes, identifies climate change as a critical boundary that must remain stable to ensure a habitable planet. Flash droughts directly intersect with this boundary, serving as both an indicator and a consequence of climate destabilization. Their effects are also deeply intertwined with other planetary boundaries, including land-system change, freshwater use, and biosphere integrity. For example, repeated flash droughts can lead to soil degradation, reduced biodiversity, and increased wildfire activity, further destabilizing ecosystems and pushing multiple planetary boundaries closer to critical thresholds. Understanding flash droughts within this broader context is essential for developing holistic strategies to address climate change and maintain Earth’s stability.
As research on flash droughts advances, new technologies and interdisciplinary approaches are playing a crucial role in improving our ability to predict, monitor, and respond to these events. Advances in big data analytics, machine learning, and remote sensing are enabling more precise detection of early drought signals, enhancing our capacity for early intervention. At the same time, cross-disciplinary collaboration among climatologists, hydrologists, ecologists, and social scientists is fostering a more comprehensive understanding of flash drought dynamics and their societal impacts. International initiatives, such as the United Nations’ Sustainable Development Goals and the Paris Agreement, are also helping to drive global action on climate adaptation and mitigation, reinforcing the need for coordinated efforts to address flash drought risk.
The research on flash droughts under climate change highlights a critical and urgent challenge that intersects with planetary boundaries science. By understanding the drivers and impacts of flash droughts, we can develop actionable solutions to mitigate their effects and build resilience in a changing climate. The integration of advanced technologies, interdisciplinary approaches, and global collaboration offers a pathway to address this challenge and return to a safe operating space within planetary boundaries. The time to act is now, as the transition to flash droughts is already underway, and their impact will only intensify without action.
Figure 3. Showcasing our joint contribution to this study, our multi-national research team.