Sea-level changes in Iceland and the influence of the North Atlantic Oscillation during the last half millennium

Margot H. Saher*, W. Roland Gehrels, Natasha L. M. Barlow, Antony J. Long, Ivan D. Haigh, Maarten Blaauw

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We present a new, diatom-based sea-level reconstruction for Iceland spanning the last ~500 years, and investigate the possible mechanisms driving the sea-level changes. A sea-level reconstruction from near the Icelandic low pressure system is important as it can improve understanding of ocean-atmosphere forcing on North Atlantic sea-level variability over multi-decadal to centennial timescales. Our reconstruction is from Viarhólmi salt marsh in Snæfellsnes in western Iceland, a site from where we previously obtained a 2000-yr record based upon less precise sea-level indicators (salt-marsh foraminifera). The 20th century part of our record is corroborated by tide-gauge data from Reykjavik. Overall, the new reconstruction shows ca0.6m rise of relative sea level during the last four centuries, of which ca0.2m occurred during the 20th century. Low-amplitude and high-frequency sea-level variability is super-imposed on the pre-industrial long-term rising trend of 0.65m per 1000 years. Most of the relative sea-level rise occurred in three distinct periods: AD 1620-1650, AD 1780-1850 and AD 1950-2000, with maximum rates of ~3±2mm/yr during the latter two of these periods. Maximum rates were achieved at the end of large shifts (from negative to positive) of the winter North Atlantic Oscillation (NAO) Index as reconstructed from proxy data. Instrumental data demonstrate that a strong and sustained positive NAO (a deep Icelandic Low) generates setup on the west coast of Iceland resulting in rising sea levels. There is no strong evidence that the periods of rapid sea-level rise were caused by ocean mass changes, glacial isostatic adjustment or regional steric change. We suggest that wind forcing plays an important role in causing regional-scale coastal sea-level variability in the North Atlantic, not only on (multi-)annual timescales, but also on multi-decadal to centennial timescales.

Original languageEnglish
Pages (from-to)23-36
Number of pages14
JournalQuaternary Science Reviews
Early online date26 Nov 2014
Publication statusPublished - 15 Jan 2015


  • Diatoms
  • Iceland
  • Little Ice Age
  • NAO
  • Ocean dynamics
  • Sea-level rise

Cite this