Rising sea level is a growing threat to coastal areas across the globe. Despite this, sea level changes at the coast remained poorly characterised, until now.

The ESA’s Climate Change Initiative’s Sea level project team has developed a new high-resolution coastal sea level product from 2002 to 2018.

To date, there has been a lack of systematic coastal sea level observations along most of the world coastlines. To address this issue, the research team created a novel altimetry-based coastal sea level data set consisting of high-resolution (~300 m) monthly sea level data along the satellite tracks, at distances of less than 3-4 km from the coastlines in general, at some locations even closer, within 1-2 km from the coast.

This data set is based on a complete reprocessing of raw radar altimetry waveforms (a process called ‘retracking’) from the Jason-1, Jason-2 and Jason-3 missions.

Coastal sea level trends (mm/yr) at the first valid point from the coast at 429 selected sites

The data set provides coastal sea level trends over 2002-2018 at 429 coastal sites across the Northeast Atlantic, Mediterranean Sea, West Africa, North Indian Ocean, Southeast Asia and Australia.

Interestingly, the coastal sea level trends show no significant difference (within +/-1 mm/yr) with open ocean trends for 80% of the studied sites - a totally unexpected result considering the theoretical predictions about the potential influence of small-scale coastal processes. However, this was found not to be true everywhere. Indeed, at a few sites, the team observed a larger sea level trend close to the coast than offshore, while in some other cases, a decrease in trend is observed as the distance to the coast decreases. Causes of such trend departures remain to be studied.


Benveniste, J., Birol, F., Calafat, F. et al. Coastal sea level anomalies and associated trends from Jason satellite altimetry over 2002–2018. Sci Data 7, 357 (2020).https://doi.org/10.1038/s41597-020-00694-w

Data Access

SEANOE repository - https://doi.org/10.17882/74354

Project information

CCI Sea level project information - https://climate.esa.int/en/projects/sea-level/