Drivers of 20th century sea-level change in southern New Zealand determined from proxy and instrumental records

TY - JOUR

T1 - Drivers of 20th century sea-level change in southern New Zealand determined from proxy and instrumental records

AU - Garrett, Ed

AU - Gehrels, W. Roland

AU - Hayward, Bruce W.

AU - Newnham, Rewi

AU - Gehrels, Maria J.

AU - Morey, Craig J.

AU - Dangendorf, Sönke

N1 - Funding Information: Fieldwork and analyses were partly supported by two Royal Society travel grants and a Royal Society Research Grant (‘Recent acceleration of sea‐level rise in the Southern Hemisphere’), both to W.R.G. Radiocarbon analyses for Mokomoko Inlet were supported by the Natural Environment Research Council Radiocarbon Facility (allocation 1793.0414). We thank Andrew Rees for assistance with fieldwork and Sophie Williams and Dan King for helpful discussions. This paper is a contribution to the NZ SeaRise Programme (RTUV1705), funded by the New Zealand Ministry of Business, Innovation and Employment; to IGCP Project 725 ‘Forecasting Coastal Change’; and to PALSEA, a working group of the International Union for Quaternary Sciences (INQUA) and Past Global Changes (PAGES). Publisher Copyright: © 2022 The Authors Journal of Quaternary Science Published by John Wiley & Sons Ltd

PY - 2022/8

Y1 - 2022/8

N2 - In this paper we present new proxy-based sea-level reconstructions for southern New Zealand spanning the last millennium. These palaeo sea-level records usefully complement sparse Southern Hemisphere proxy and tide-gauge sea-level datasets and, in combination with instrumental observations, can test hypotheses about the drivers of 20th century global sea-level change, including land-based ice melt and regional sterodynamics. We develop sea-level transfer functions from regional datasets of salt-marsh foraminifera to establish a new proxy-based sea-level record at Mokomoko Inlet, at the southern tip of the South Island, and to improve the previously published sea-level reconstruction at Pounawea, located about 110 km to the east. Chronologies are based on radiocarbon, radiocaesium, stable lead isotope and pollen analyses. Both records are in good agreement and show a rapid sea-level rise in the first half of the 20th century that peaked in the 1940s. Previously reported discrepancies between proxy-based sea-level records and tide-gauge records are partially reconciled by accounting for barystatic and sterodynamic components of regional sea-level rise. We conclude that the rapid sea-level rise during the mid-20th century along the coast of southern New Zealand was primarily driven by regional thermal expansion and ocean dynamics.

AB - In this paper we present new proxy-based sea-level reconstructions for southern New Zealand spanning the last millennium. These palaeo sea-level records usefully complement sparse Southern Hemisphere proxy and tide-gauge sea-level datasets and, in combination with instrumental observations, can test hypotheses about the drivers of 20th century global sea-level change, including land-based ice melt and regional sterodynamics. We develop sea-level transfer functions from regional datasets of salt-marsh foraminifera to establish a new proxy-based sea-level record at Mokomoko Inlet, at the southern tip of the South Island, and to improve the previously published sea-level reconstruction at Pounawea, located about 110 km to the east. Chronologies are based on radiocarbon, radiocaesium, stable lead isotope and pollen analyses. Both records are in good agreement and show a rapid sea-level rise in the first half of the 20th century that peaked in the 1940s. Previously reported discrepancies between proxy-based sea-level records and tide-gauge records are partially reconciled by accounting for barystatic and sterodynamic components of regional sea-level rise. We conclude that the rapid sea-level rise during the mid-20th century along the coast of southern New Zealand was primarily driven by regional thermal expansion and ocean dynamics.

KW - barystatic

KW - foraminifera

KW - sea level

KW - sterodynamic

KW - transfer function

UR - http://www.scopus.com/inward/record.url?scp=85125957849&partnerID=8YFLogxK

UR - https://figshare.com/articles/dataset/Surface_and_core_foraminifera_from_Mokomoko_Inlet_southern_New_Zealand/17061224

UR - https://figshare.com/articles/dataset/Core_pollen_data_from_Mokomoko_Inlet_southern_New_Zealand/17061449

UR - https://figshare.com/articles/dataset/Relative_sea-level_data_from_Mokomoko_Inlet_and_Pounawea_in_HOLSEA_format/19134335

UR - https://figshare.com/articles/dataset/Chronostratigraphic_data_from_Mokomoko_Inlet_southern_New_Zealand/17062085

U2 - 10.1002/jqs.3418

DO - 10.1002/jqs.3418

M3 - Article

AN - SCOPUS:85125957849

SN - 0267-8179

VL - 37

SP - 1025

EP - 1043

JO - Journal of Quaternary Science

JF - Journal of Quaternary Science

IS - 6

ER -