Preprints
https://doi.org/10.5194/essd-2024-46
https://doi.org/10.5194/essd-2024-46
21 Feb 2024
 | 21 Feb 2024
Status: a revised version of this preprint was accepted for the journal ESSD and is expected to appear here in due course.

Probabilistic reconstruction of sea-level changes and their causes since 1900

Sönke Dangendorf, Qiang Sun, Thomas Wahl, Philip Thompson, Jerry X. Mitrovica, and Ben Hamlington

Abstract. Coastal communities around the world are increasingly exposed to extreme events that have been exacerbated by rising sea levels. Sustainable adaptation strategies to cope with the associated threats require comprehensive understanding of past and possible future changes. Yet, many coastlines lack accurate long-term sea level observations. Here, we introduce a novel probabilistic near-global reconstruction of relative sea-level changes and their causes over the period 1900 to 2021. The reconstruction is based on tide gauge records and incorporates prior knowledge about physical processes from ancillary observations and geophysical model outputs. We demonstrate good agreement between the reconstruction and satellite altimetry and tide gauges (if local vertical land motion is considered). Validation against steric height estimates based on independent temperature and salinity observations over their overlapping periods shows moderate to good agreement in terms of variability, though with larger trends in three out of six regions. The linear long-term trend of the resulting global mean sea level (GMSL) record is 1.5±0.19 mmyr-1 since 1900, a value consistent with central estimates from the 6th Assessment Report of the Intergovernmental Panel on Climate Change. Multidecadal trends in GMSL have varied with enhanced rates in the 1930s, near-zero rates in the 1960s, and a persistent acceleration (0.08±0.04 mmyr-2) thereafter. As a result, most recent rates have exceeded 4 mmyr-1. Largest regional rates (>10 mmyr-1) over the same period have been detected in coastal areas near western boundary currents and the larger tropical Indo-Pacific region. Barystatic mass changes due to ice-melt and terrestrial water storage variations have dominated the sea-level acceleration at global scales, but sterodynamic processes are the most crucial factor locally, particularly at low latitudes and away from major melt sources. These results demonstrate that the new reconstruction provides valuable insights into historical sea-level change and its contributing causes complementing observational records in areas where they are sparse or absent.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Sönke Dangendorf, Qiang Sun, Thomas Wahl, Philip Thompson, Jerry X. Mitrovica, and Ben Hamlington

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2024-46', Anonymous Referee #1, 01 Apr 2024
  • RC2: 'Comment on essd-2024-46', Anonymous Referee #2, 06 May 2024

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2024-46', Anonymous Referee #1, 01 Apr 2024
  • RC2: 'Comment on essd-2024-46', Anonymous Referee #2, 06 May 2024
Sönke Dangendorf, Qiang Sun, Thomas Wahl, Philip Thompson, Jerry X. Mitrovica, and Ben Hamlington

Data sets

Kalman Smoother Sea Level Reconstruction Sönke Dangendorf https://doi.org/10.5281/zenodo.10621070

Model code and software

Kalman Smoother Sea Level Reconstruction Sönke Dangendorf https://doi.org/10.5281/zenodo.10621070

Sönke Dangendorf, Qiang Sun, Thomas Wahl, Philip Thompson, Jerry X. Mitrovica, and Ben Hamlington

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Short summary
Sea-level information from the global ocean is sparse in time and space with comprehensive data being limited to the period since 2005. Here we provide a novel reconstruction of sea level and its contributing causes as determined by a Kalman Smoother approach applied to tide gauge records over the period 1900 to 2021. The new reconstruction shows a continuing acceleration in global mean sea level rise since 1970 dominated by melting land ice. Regionally contributors vary significantly by region.
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