Reconstructing sea level rise from global 945 tide gauges since 1900

Abstract

Tide gauges record sea level changes along coastlines. They are widely used to determine the twentieth century global mean sea level (GMSL) rise. However, a major issue in tide gauge data is the presence of various, substantial, and sometimes persistent data gaps, which hinder our understanding of sea level rise, especially at regional and local scales. Whilst the GMSL reconstructions have been provided by several influential studies, reconstructions at the exact sites of tide gauges are rarely available. Here, we present sea level reconstructions at global 945 tide gauges, covering the period from 1900 to 2022. Our approach relies on a data assimilation technique that integrates various physical sea level observations and predictions, including sea level simulations from 35 climate models. A prominent feature in our reconstruction is that it provides an ensemble of 35 reconstructions at each site of tide gauge, providing continuous and refined sea level time series. This ensemble reconstruction allows for direct statistical assessments, e.g., average, median, spread, and percentile. The average of reconstructed sea level across 945 tide gauges reveals a GMSL rate of 1.75 ± 0.05 mm yr-1 over 1900-2020, and shows strong agreement with other GMSL reconstructions for both the curves of time series and overall trends. At local scale, our reconstructions are comparable to an independent reconstruction. Despite some rate differences at certain locations, the reconstructed sea level trends closely follow the raw records when they are available, emphasizing the importance of the observations at tide gauges. Our sea level reconstructions offer a valuable resource for improving global and regional sea level projections, validating climate model performance, and informing coastal adaptation strategies through understanding the sea level rise over the past century. The reconstructed sea level is available at 10.5281/zenodo.15385035 (Mu, 2025).