Several processes contributing to coastal relative sea-level (RSL) change in the North Atlantic Ocean are
observed and/or predicted to have distinctive spatial expressions that vary by latitude. To expand the
latitudinal range of RSL records spanning the past ~3000 years and the likelihood of recognizing the
characteristic fingerprints of these processes, we reconstructed RSL at two sites (Big River and Placentia)
in Newfoundland from salt-marsh sediment. Bayesian transfer functions established the height of former
sea level from preserved assemblages of foraminifera and testate amoebae. Age-depth models constrained
by radiocarbon dates and chronohorizons estimated the timing of sediment deposition. During
the past ~3000 years, RSL rose by ~3.0mat Big River and by ~1.5mat Placentia. A locally calibrated
geotechnical model showed that post-depositional lowering through sediment compaction was minimal.
To isolate and quantify contributions to RSL from global, regional linear, regional non-linear, and localscale
processes, we decomposed the new reconstructions (and those in an expanded, global database)
using a spatio-temporal statistical model. The global component confirms that 20th century sea-level
rise occurred at the fastest, century-scale rate in over 3000 years (P > 0.999). Distinguishing the contributions
from local and regional non-linear processes is made challenging by a sparse network of reconstructions.
However, only a small contribution from local-scale processes is necessary to reconcile RSL
reconstructions and modeled RSL trends. We identified three latitudinally-organized groups of sites that
share coherent regional non-linear trends and indicate that dynamic redistribution of ocean mass by
currents and/or winds was likely an important driver of sea-level change in the North Atlantic Ocean
during the past ~3000 years.
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Status = Published
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Academic Unit = Faculty of Science and Engineering: Mathematics and Statistics
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Type = Article
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Academic Unit = Faculty of Science and Engineering
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Trinity College Dublin ->
Geography
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School of Natural Sciences
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Orson van de Plassche,
Troy Hill,
Andrea Hawkes,
Dan Charman,
Benjamin Horton,
Niamh Cahill,
Robert Kopp,
Matthew Brain,
Robert Barnett,
Robin Edwards
and 3 others