Sea level alert: previous estimates were severely underestimated
04.03.2026
The sea level along coastlines is much higher than indicated in many coastal impact studies, with differences that can reach 1-1.5 meters in vulnerable areas such as Southeast Asia. This is the result of research conducted by Philip Minderhoud (University of Padua, Wageningen University & Research, Deltares Research Institute), an expert lecturer in coastal delta subsidence and relative sea level rise, and Katharina Seeger (University of Padua, Wageningen University & Research, University of Cologne), a post-doctoral researcher specializing in coastal elevation and sea level rise impacts.
Published in "Springer Nature," the study highlights that over 90% of existing analyses use a sea level reference that is lower than what is actually measured. "Our results demonstrate the need to review—and in most cases update—the methodological foundations on which current coastal risk studies are based," explain Minderhoud and Seeger.
Many studies rely on global geoid models, which do not take into account local factors such as winds and ocean currents. "It is crucial to integrate actual sea level measurements," clarifies Philip Minderhoud. And while satellites provide global measurements, data integration is not immediate, adds Katharina Seeger.
A study on the Mekong Delta, for example, revealed that the surface water level was very close to ground elevation, contrary to estimates. This issue was also found in other regions of Southeast Asia and around the world. Most of the analyzed studies underestimate the extent and exposure of coastal zones and populations. With a one-meter sea level rise, areas below sea level would be 37% greater than previously estimated, and exposed populations would increase by 68%, up to 132 million more people. "If the sea level is already higher than thought, the impacts of future rises will manifest sooner than expected," notes Minderhoud.
It is necessary to reassess the methodologies of existing studies and update coastal adaptation strategies. "We hope that this approach can become a new standard for more accurate assessments of future coastal impacts," conclude the authors.
For more information, see the video prepared by Wageningen University & Research.
