A systematic review of 385 coastal hazard studies reveals widespread methodological flaws that significantly underestimate sea level rise impacts. Most assessments fail to properly align coastal elevation data with actual local sea levels, leading to errors potentially as large as a century of projected sea level rise for affected regions. The review found that 73% of studies lacked proper documentation of sea level height, coastal elevation, and vertical datums.

Researchers identified that most studies incorrectly assume global geoid or ellipsoid values represent actual coastal sea levels, when in reality mean dynamic topography can deviate by several meters due to ocean currents, temperature, and salinity. This omission is particularly problematic in data-sparse regions of Africa and Asia, where gravitational data paucity compounds the error. The study evaluated literature from 2009-2025, with over half published in the past five years, spanning global to regional assessments of SLR, storm surge, tsunami, and compound flooding risks.

To address these shortcomings, researchers converted several state-of-the-art global digital elevation models to coastal sea-level height and provided them for immediate use. They also developed concrete recommendations including data documentation guidelines and peer-review checklists to ensure correct vertical datum alignment in future publications. These methodological improvements aim to eliminate the community-wide blind spot that has led to systematic underestimations of coastal sea level rise and hazard impact assessments.