Strong influence of El Niño Southern Oscillation on flood risk around the world

TLDR

El Niño Southern Oscillation (ENSO) drives global hydrological changes, yet its impact on the socioeconomic consequences of flooding remains largely unknown. This study conducts the first global assessment of ENSO’s influence on flood risk, quantified by economic damage, exposed population, and GDP. The analysis reveals that ENSO years generate reliable flood‑risk anomalies in basins covering nearly half of the planet, enabling probabilistic risk projections that can inform disaster planning such as pre‑positioning food and medicine supplies.

Abstract

Significance El Niño Southern Oscillation (ENSO) affects hydrological processes around the globe. However, little is known about its influence on the socioeconomic impacts of flooding (i.e., flood risk). We present, to our knowledge, the first global assessment of ENSO’s influence on flood risk in terms of economic damage and exposed population and gross domestic product. We show that reliable flood risk anomalies exist during ENSO years in basins spanning almost half of Earth’s surface. These results are significant for flood-risk management. Because ENSO can be predicted with lead times of several seasons with some skill, the findings pave the way for developing probabilistic flood-risk projections. These could be used for improved disaster planning, such as temporarily increasing food and medicine stocks by relief agencies.