The causes of sea-level rise since 1900
Abstract
The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood. Previous assessments found that the summed contributions of ice-mass loss, terrestrial water storage and thermal expansion of the ocean could not be reconciled with observed changes in global-mean sea level, implying that changes in sea level or some contributions to those changes were poorly constrained. Recent improvements to observational data, our understanding of the main contributing processes to sea-level change and methods for estimating the individual contributions, mean another attempt at reconciliation is warranted. Here we present a probabilistic framework to reconstruct sea level since 1900 using independent observations and their inherent uncertainties. The sum of the contributions to sea-level change from thermal expansion of the ocean, ice-mass loss and changes in terrestrial water storage is consistent with the trends and multidecadal variability in observed sea level on both global and basin scales, which we reconstruct from tide-gauge records. Ice-mass loss—predominantly from glaciers—has caused twice as much sea-level rise since 1900 as has thermal expansion. Mass loss from glaciers and the Greenland Ice Sheet explains the high rates of global sea-level rise during the 1940s, while a sharp increase in water impoundment by artificial reservoirs is the main cause of the lower-than-average rates during the 1970s. The acceleration in sea-level rise since the 1970s is caused by the combination of thermal expansion of the ocean and increased ice-mass loss from Greenland. Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900.
Additional Information
© 2020 Nature Publishing Group. Received 21 December 2019; Accepted 08 June 2020; Published 19 August 2020. All figures were made using Generic Mapping Tools (GMT). Parts of this research (T.F., F.L., S.A., L. Caron) were conducted at the Jet Propulsion Laboratory, which is operated for NASA under contract with the California Institute of Technology. S.D. acknowledges the University of Siegen for funding a research stay at JPL. L. Cheng is supported by National Key R&D Program of China (2017YFA0603200). Data availability: The resulting global and basin-scale reconstructions, the time series of global and basin sea-level changes and its contributors, grids with local sea-level and solid-Earth deformation due to contemporary GRD effects, and the individual ensemble members are available at https://doi.org/10.5281/zenodo.3862995. Code availability: The codes to compute the ensemble of observed sea-level changes and contributing processes, and the post-processing routines to compute statistics and to generate the figures are available at https://github.com/thomasfrederikse/sealevelbudget_20c. Author Contributions: T.F. and F.L. conceived and designed the study. L. Caron and S.A. provided the GIA data and provided guidance on the solid-Earth processes. D.P. provided glacier datasets and helped interpret the underlying uncertainties. V.W.H. provided the TWS reconstruction. P.H. prepared the tide-gauge dataset. L.Z. and L. Cheng helped analyse the steric datasets. Y.-H.W. created the reservoir databases. S.D. provided guidance on the sea-level reconstruction approach. T.F. performed the analysis and wrote the manuscript. All authors contributed to the discussion and helped write the manuscript. The authors declare no competing interests.Attached Files
Supplemental Material - 41586_2020_2591_Fig10_ESM.webp
Supplemental Material - 41586_2020_2591_Fig4_ESM.webp
Supplemental Material - 41586_2020_2591_Fig5_ESM.webp
Supplemental Material - 41586_2020_2591_Fig6_ESM.webp
Supplemental Material - 41586_2020_2591_Fig7_ESM.webp
Supplemental Material - 41586_2020_2591_Fig8_ESM.webp
Supplemental Material - 41586_2020_2591_Fig9_ESM.webp
Supplemental Material - 41586_2020_2591_Tab1_ESM.jpg
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Additional details
- Eprint ID
- 105088
- Resolver ID
- CaltechAUTHORS:20200824-150308335
- NASA/JPL/Caltech
- University of Siegen
- 2017YFA0603200
- National Key Research and Development Program of China
- Created
-
2020-08-24Created from EPrint's datestamp field
- Updated
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2023-06-01Created from EPrint's last_modified field