Reassessment of 20th century global mean sea level rise

Sönke Dangendorf*, Marta Marcos, Guy Wöppelmann, Clinton P. Conrad, Thomas Frederikse, Riccardo Riva

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

157 Citations (Scopus)

Abstract

The rate at which global mean sea level (GMSL) rose during the 20th century is uncertain, with little consensus between various reconstructions that indicate rates of rise ranging from 1.3 to 2 mm•y-1. Here we present a 20th-century GMSL reconstruction computed using an area-weighting technique for averaging tide gauge records that both incorporates up-to-date observations of vertical land motion (VLM) and corrections for local geoid changes resulting from ice melting and terrestrial freshwater storage and allows for the identification of possible differences compared with earlier attempts. Our reconstructed GMSL trend of 1.1 ± 0.3 mm•y-1 (1s) before 1990 falls below previous estimates, whereas our estimate of 3.1 ± 1.4 mm•y-1 from 1993 to 2012 is consistent with independent estimates from satellite altimetry, leading to overall acceleration larger than previously suggested. This feature is geographically dominated by the Indian Ocean-Southern Pacific region, marking a transition from lower-than-average rates before 1990 toward unprecedented high rates in recent decades. We demonstrate that VLM corrections, area weighting, and our use of a common reference datum for tide gauges may explain the lower rates compared with earlier GMSL estimates in approximately equal proportion. The trends and multidecadal variability of our GMSL curve also compare well to the sum of individual contributions obtained from historical outputs of the Coupled Model Intercomparison Project Phase 5. This, in turn, increases our confidence in process-based projections presented in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.

Original languageEnglish
Pages (from-to)5946-5951
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number23
DOIs
Publication statusPublished - 6 Jun 2017

Keywords

  • Climate change
  • Fingerprints
  • Global mean sea level
  • Tide gauges
  • Vertical land motion

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