Droughts and floods can seriously disrupt daily life, damage ecosystems, and put pressure on both local and global economies. To better understand how these water-related extremes develop and spread, researchers from the University of Texas at Austin conducted a study that revealed powerful climate connections between distant regions of the planet.

ENSO and Global Water Extremes

A recent study published in AGU Advances showed that over the past 20 years, the ENSO climate pattern (El Niño–Southern Oscillation), which includes both El Niño and La Niña phases, has played a crucial role in driving extreme changes in the global water balance. ENSO can synchronize extreme weather events, leading to unusually wet or dry conditions occurring simultaneously on different continents.

According to Bridget Scanlon, a research scientist at the Bureau of Economic Geology at the University of Texas, understanding these global patterns has practical value: “By looking at the situation on a global scale, we can identify which regions are experiencing water surpluses or shortages at the same time. This directly affects water availability, food production, trade, and other global processes.” Simultaneous droughts or floods in multiple regions can have a significant impact on agriculture, trade, and humanitarian planning.

A Comprehensive Approach to Water Resource Analysis

Total water storage is an important climate indicator that accounts for all forms of water in a region: rivers, lakes, snow, ice, soil moisture, and groundwater. This comprehensive approach helps us better understand how water moves and changes over time.

This study is among the first to examine global water balance extremes in connection with ENSO on a worldwide scale. Such analysis revealed how extremely wet and dry conditions are interconnected across vast distances. Lead author Ashraf Rateb notes: “Most studies focus only on the frequency or intensity of extreme events, but by definition, these events are rare, making it difficult to analyze changes over time. We studied the spatial connection of extremes, which provided much more information about the patterns that drive droughts and floods around the world.”

Using Satellite Data

To assess the global water balance, scientists used gravity data collected by NASA’s GRACE and GRACE Follow-On satellites. These data allow researchers to track changes in water mass over areas about 300–400 kilometers wide, roughly the size of the state of Indiana.

Wet extremes were defined as water balance levels above the 90th percentile for a region, while dry extremes were those below the 10th percentile.

ENSO and Examples of Global Anomalies

The analysis showed that unusual ENSO activity can simultaneously trigger extreme conditions in different parts of the world. For example, in the mid-2000s, El Niño coincided with severe drought in southern Africa, and in 2015–2016, with drought in the Amazon. Meanwhile, La Niña in 2010–2011 brought exceptional rainfall to Australia, southeastern Brazil, and southern Africa.

Global Shifts in Water Balance

The study also identified a broader shift in global water behavior around 2011–2012. Before 2011, unusually wet conditions were more common worldwide, but after 2012, dry extremes began to dominate. Scientists link this to a long-term climate pattern in the Pacific Ocean that influences how ENSO affects global water resources.

The Importance of Satellite Observations

Although GRACE and GRACE-FO satellite data cover only 22 years (2002–2024), they clearly demonstrate the close link between Earth’s climate and water systems. As Jay T. Rieger, deputy science lead for the GRACE-FO mission at NASA’s Jet Propulsion Laboratory, points out, “These data really capture the rhythm of major climate cycles like El Niño and La Niña, and their impact on the floods and droughts that humanity faces. Everything that happens in the Pacific Ocean ultimately affects us on land.”

A New Perspective on Water Management

Scanlon emphasizes that the study’s findings call for a rethink in how we discuss water issues. Instead of focusing solely on shortages, it’s important to prepare for fluctuations between excess and scarcity. “People often say that water is running out, but in reality, it’s about managing extremes,” Scanlon notes. “And that’s a completely different approach.”