Global sea-level rise in the early Holocene revealed from North Sea peats: Supplementary Information

This is the Supplementary Information of the paper Global sea-level rise in the early Holocene revealed from North Sea peats of Hijma et al. (2025). It contains four sections:

Section 1: Geological sea-level data in HOLSEA formatSea-level indicators from drowned peats of the North Sea floor were analyzed using the HOLSEA-protocol, with some expansions to the original format and including Bayesian age-calibration. The repository provides: detailed technical description of all database fields in order of processing workflow (01.1), the database itself (01.2), CQL text files for use in OxCal radiocarbon calibration software (01.3) with result evaluation data (01.4).

Section 2: Annotated photos, XRF and diatom analyses on North Sea floor coresThe repository provides detailed descriptions of integrated XRF and Diatom results (02.1), annotated core photos (02.2) and diatom analysis diagrams (02.3) of vibrocores taken during cruises in 2017 and 2018 (Pelagia vessel). It also provides a movie of the vibrocoring system we used (02.4).

Section 3: Background subsidence raster maps for the study areaThe analysis in Hijma et al. (2025) has corrected all geological sea-level data (Section 1) for background basin subsidence, using geological mapping compiled for this purpose from multiple sources (academia, industry and national geological surveys, offshore and onshore). The repository provides: detailed technical description of the mapping compilation and conversion to subsidence rate grids (03.1), sets of gridded input data (in geoTIFF format) for Base Quaternary (03.2) and presumed water depth at the time (03.3), gridded output data: mean, max and min rates as averaged over 2.582 Ma (03.40-42) respectively 1.864 Ma (03.50-52).

Section 4: GIA-modelling and EIV-IGP-modelling output and ice-sheet volume reconstructionsThe analysis in Hijma et al. (2025) has used eight selected GIA-models to undo the sea-level data in Section 1 from European GIA signals and arrive at a residual RSL signal meaningful to global intercomparison. The processed sea-level signal, with uncertainty terms from the ensemble of GIA-models, was analyzed using the EIV-IGP-model (Cahill et al. 2015,2016) to generate the global sea-level histories of the main paper. The repository provides the output for the eight GIA-models, the residual RSL-data, the results of the EIV-IGP modelling and the literature-based ice-sheet volume reconstructions (04.1).

ReferencesCahill, N., Kemp, A. C., Horton, B. P. & Parnell, A. C. Modeling sea-level change using errors-in-variables integrated Gaussian processes. Ann. Appl. Stat. 9, 547-571 (2015). https://doi.org:10.1214/15-AOAS824Cahill, N., Kemp, A. C., Horton, B. P. & Parnell, A. C. A Bayesian hierarchical model for reconstructing relative sea level: from raw data to rates of change. Clim. Past 12, 525-542 (2016). https://doi.org:10.5194/cp-12-525-2016Hijma et al. Global sea-level rise in the early Holocene revealed from North Sea peats. Nature 639 (8055), 652-657 (2025). https://doi.org: 10.1038/s41586-025-08769-7