Relative sea-level change in Newfoundland, Canada during the past 3000 years

• Main Authors: Kemp, Andrew C., Wright, Alexander J., Edwards, Robin J., Barnett, Robert, Brain, Matthew J., Kopp, Robert E., Cahill, Niamh, Horton, Benjamin P., Charman, Daniel J., Hawkes, Andrea D., Hill, Troy D., van de Plaasche, Orson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2018
• Subjects: Big River; Canada; Newfoundland; North Atlantic
• Online Access: https://mural.maynoothuniversity.ie/13162/; https://mural.maynoothuniversity.ie/13162/1/NC_maths%26stats_relative.pdf

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 ~3.0 m at Big River and by ~1.5 m at 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.