According to a study covering the last two decades, the primary factor contributing to extreme changes in global water supplies is ENSO (El Niño–Southern Oscillation). These climatic processes cause simultaneous anomalies in precipitation across different continents — both in terms of excess moisture and deficiency.
Bridget Scanlon, one of the authors of the study, noted: “At a global level, we can identify which regions are simultaneously experiencing excess or deficiency of moisture. This certainly impacts water availability, agricultural production, and food trade — all of which have global significance.”
For their analysis, the team used data from NASA's GRACE and GRACE-FO satellites, which detect gravitational anomalies caused by changes in water mass. This approach allows for a more accurate assessment of total water supplies, including rivers, lakes, soil moisture, and groundwater.
The study also identified specific examples of synchronization of water extremes. For instance, the El Niño of the mid-2000s coincided with a severe drought in Southern Africa, while in 2015-2016, similar conditions were observed in the Amazon. At the same time, La Niña in 2010-2011 contributed to the creation of very wet conditions in Australia, southeastern Brazil, and Southern Africa.
Additionally, the research recorded a global shift: until 2011, the world faced more frequent extremely wet conditions, whereas after 2012, there has been a predominance of dry extremes.
Jay T. Rieger, who was not involved in the study, emphasized that satellite observations open new horizons for understanding the impact of climate cycles on water crises. “They truly capture the rhythm of major climate cycles, such as El Niño and La Niña, as well as their influence on floods and droughts that we all face. These are not just processes in the Pacific Ocean — their actions result in consequences for all of us on land,” he added.
In conclusion, Bridget Scanlon noted that the findings of the study highlight the need to revise approaches to water resource management: instead of focusing solely on water scarcity, it is important to plan for and consider fluctuations between excess and deficiency.
