Study Finds Most Coastal Sea Level Assessments Underestimate Heights

A new study published Wednesday in the journal Nature reveals that the vast majority of scientific assessments of coastal sea level rise have underestimated current ocean heights worldwide, potentially exposing hundreds of millions more people to flooding risks than previously calculated. Researchers Katharina Seeger and Philip Minderhoud, from Wageningen University in the Netherlands, analyzed 385 peer-reviewed papers on coastal hazards published between 2009 and 2025, finding that 90 percent relied on outdated gravitational models known as geoids, which ignore key local factors like tides, winds, and ocean currents.

These models approximate mean sea level based on Earth's gravity and rotation but fail to capture dynamic influences that can elevate water levels significantly in certain regions. As a result, the studies underestimated coastal sea levels by an average of 24 to 27 centimeters, or about 9 to 10 inches, with discrepancies reaching up to 3 meters in parts of Southeast Asia and the South Pacific. In extreme cases, such as some areas of the Indo-Pacific, the underestimation exceeded 5 meters. The analysis showed that fewer than 1 percent of the papers correctly...