Researchers Detail Geoid Model Settings Behind Revised Coastal Sea-Level Estimates
An addendum outlines the exact geoid model configurations used in a recent meta-analysis that found sea levels higher than most coastal risk studies assume.
In this addendum, the team provides a step-by-step account of the geoid model parameters that underpin their earlier finding of higher-than-expected sea levels along coasts. They retrieved point-wise geoid height anomalies for the entire planet from ICGEM’s open service, using a 0.085° grid for EGM96, EGM2008 and GOCO06s, and a 1.000° grid for GOCO2025s and DIR R4, with download dates ranging from August 2023 to October 2025.
Each model’s zero-degree term and tide-free configuration were retained, and no additional filtering was applied. Interpolation into global rasters employed multiquadric radial basis functions via ArcGIS Pro, optimizing kernel parameters and using 10-15 nearest neighbours. Subsequent calculations derived coastal offsets and mean dynamic topography, with final visualizations resampled to 1° and statistics reported at 1 km resolution. These methodological details ensure full reproducibility of the sea-level assessment presented in the original Nature article.
Why it matters
Clear methodology lets other scientists verify and build on the finding that many coastal hazard models underestimate sea-level rise.
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