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

Sea-level changes in Iceland and the influence of the North Atlantic Oscillation during the last half millennium
Sea-level changes in Iceland and the influence of the North Atlantic Oscillation during the last half millennium
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 Viðarhólmi 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 ca 0.6 m rise of relative sea level during the last four centuries, of which ca 0.2 m 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 0.65 m 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 ± 2 mm/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.
Diatoms, Ocean dynamics, Iceland, Little Ice Age, Sea-level rise, NAO
0277-3791
23-36
Saher, Margot H.
429b77fb-84ff-4e50-8966-09525d3cf6be
Gehrels, W. Roland
ad913def-9ab9-4218-8cdf-da02d7d04994
Barlow, Natasha L.M.
5b4c8b9b-eaf6-4b8a-9628-15e3a764c3d4
Long, Antony J.
81a3a57c-4be9-4c06-86d9-8003330fcf19
Haigh, Ivan D.
945ff20a-589c-47b7-b06f-61804367eb2d
Blaauw, Maarten
42f13bb7-e011-40f3-a218-ff207204b833
Saher, Margot H.
429b77fb-84ff-4e50-8966-09525d3cf6be
Gehrels, W. Roland
ad913def-9ab9-4218-8cdf-da02d7d04994
Barlow, Natasha L.M.
5b4c8b9b-eaf6-4b8a-9628-15e3a764c3d4
Long, Antony J.
81a3a57c-4be9-4c06-86d9-8003330fcf19
Haigh, Ivan D.
945ff20a-589c-47b7-b06f-61804367eb2d
Blaauw, Maarten
42f13bb7-e011-40f3-a218-ff207204b833

Saher, Margot H., Gehrels, W. Roland, Barlow, Natasha L.M., Long, Antony J., Haigh, Ivan D. and Blaauw, Maarten (2015) Sea-level changes in Iceland and the influence of the North Atlantic Oscillation during the last half millennium. Quaternary Science Reviews, 108, 23-36. (doi:10.1016/j.quascirev.2014.11.005).

Record type: Article

Abstract

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 Viðarhólmi 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 ca 0.6 m rise of relative sea level during the last four centuries, of which ca 0.2 m 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 0.65 m 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 ± 2 mm/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.

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More information

Published date: 15 January 2015
Keywords: Diatoms, Ocean dynamics, Iceland, Little Ice Age, Sea-level rise, NAO
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 374950
URI: http://eprints.soton.ac.uk/id/eprint/374950
ISSN: 0277-3791
PURE UUID: bb136210-9b2e-4406-9d9c-a41a680793c0
ORCID for Ivan D. Haigh: ORCID iD orcid.org/0000-0002-9722-3061

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Date deposited: 06 Mar 2015 11:59
Last modified: 15 Mar 2024 03:26

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Contributors

Author: Margot H. Saher
Author: W. Roland Gehrels
Author: Natasha L.M. Barlow
Author: Antony J. Long
Author: Ivan D. Haigh ORCID iD
Author: Maarten Blaauw

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