A groundbreaking study published in Nature Communications by researchers at the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea reveals an alarming acceleration in the emergence of prolonged, multi-year droughts across the globe due to anthropogenic climate change. These extensive drought periods, termed “Day Zero Droughts” (DZDs), signify the point at which water demand in a region first surpasses available freshwater supply, threatening essential urban and agricultural water needs—and putting billions of people at risk within the coming decades.
Through advanced computational modeling and climate simulations, the study meticulously identifies the temporal and spatial patterns of DZD emergence worldwide, projecting an unprecedented water scarcity crisis in the Anthropocene epoch. By integrating hydrological stress factors such as prolonged precipitation deficits, reduced river discharge, and increased water consumption—while specifically excluding groundwater reservoirs for conservatism—the research paints a sobering picture of an accelerating trend that is far more imminent and widespread than previously anticipated.
The investigative team employed state-of-the-art climate models forced with the SSP3-7.0 and SSP2-4.5 greenhouse gas concentration trajectories, which represent medium to high emission futures. This approach allowed for an assessment of water scarcity risks under varying degrees of global warming and socio-economic developments. The models simulate complex interactions within the hydrological cycle, capturing compound extremes that drive water availability below critical thresholds vital for human and ecosystem survival.
Spatial analysis reveals specific global hotspots where DZD risks are projected to materialize earliest and most severely. These include the Mediterranean basin, southern Africa, and selected regions in North America, where increasing drought frequency is coupled with dense urban populations and high agricultural dependency. Particularly, cities such as Cape Town and Chennai serve as early warning cases, having experienced near-DZD events in recent years, thus illustrating the real-world implications of modeled projections.
Crucially, the study quantifies the temporal dimension, demonstrating that approximately 35% of vulnerable global regions are likely to face their first DZD event within the next 15 years. This rapid onset of crisis conditions calls for urgent attention as it underscores a shrinking window for adaptation measures. The cumulative number of people exposed to these conditions is estimated to reach around 750 million by 2100, with urban residents accounting for 470 million and rural communities constituting 290 million—a stark indicator of the far-reaching social consequences.
The Mediterranean region is anticipated to register the highest urban exposure, where climate-induced drought risks intersect with extensive water infrastructure and diverse water usage sectors. By contrast, Northern and Southern Africa, alongside parts of Asia, confront the most acute rural impacts, where agricultural livelihoods and ecosystem services are intrinsically tied to fluctuating freshwater availability. This regional disparity highlights the importance of tailored, location-specific mitigation and adaptation strategies.
Researchers further project a dire risk to major water reservoirs that act as buffers against intermittent droughts. The simulations suggest that 14% of these critical infrastructures could run dry during their initial DZD event, amplifying the severity of hydrological stress and threatening water security on a massive scale. This reservoir depletion not only jeopardizes immediate water access but also undermines food production, energy generation, and ecosystem resilience.
According to lead author Ms. Ravinandrasana, the study emphasizes that “Day Zero Droughts are no longer hypothetical scenarios of the future but unfolding realities today.” The data-driven forecasts reinforce that even if the global climate trajectory adheres to the ambitious 1.5°C warming limit set by international agreements, hundreds of millions of people will still face unprecedented water deficits in their lifetimes.
The research methodology advances our understanding by focusing on hydrological compound extremes—events where multiple stressors coincide and amplify impacts—and moving beyond simplistic single-variable assessments. This nuanced modeling captures the dynamics of drought formation with greater fidelity, allowing for better prediction of the timing of DZD events, which are pivotal for resource planning and disaster preparedness.
From a policy perspective, the findings wield significant influence as they underscore the urgency of developing comprehensive and sustainable water management systems worldwide. Strategies must integrate anticipatory planning for DZD emergence, including enhancing water-use efficiency, expanding alternative supply sources, and implementing adaptive governance frameworks that are sensitive to local vulnerabilities and socio-economic contexts.
Moreover, the research signals the pressing need for global climate change mitigation to slow the alarming progression of water scarcity. This includes reducing emissions, transitioning to renewable energy sources, and preserving natural water cycles. Without concerted international efforts, the frequency and intensity of DZDs—and their consequent humanitarian, economic, and ecological ramifications—will likely intensify unabated.
Ultimately, this study equips scientists, policymakers, and the public with critical insights into one of the most consequential challenges of the 21st century: the unprecedented risk of global water scarcity emerging within decades. It is a clarion call to action, demanding immediate coordinated responses to safeguard water security for future generations in an era increasingly defined by climate uncertainty.
Subject of Research: Not applicable
Article Title: The First Emergence of Unprecedented Global Water Scarcity in the Anthropocene
News Publication Date: 23-Sep-2025
Web References:
10.1038/s41467-025-63784-6
Image Credits: Institute for Basic Science
Keywords: Droughts, Natural disasters, Earth sciences, Climate data, Anthropogenic climate change, Climate change, Climate change mitigation, Earth climate, Hydrology, Water resources, Hydrological cycle, Freshwater resources, Water supply, Water scarcity, Climate modeling, Applied ecology, Ecological modeling
