EGU22-5675, updated on 09 Jan 2023
https://doi.org/10.5194/egusphere-egu22-5675
EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Late Holocene sea-level change in southern New Zealand 

Ed Garrett1, Roland Gehrels1, Bruce Hayward2, Rewi Newnham3, Maria Gehrels1, Craig Morey4, and Sonke Dangendorf5,6
Ed Garrett et al.
  • 1University of York, Department of Environment and Geography, United Kingdom of Great Britain – England, Scotland, Wales (ed.garrett@york.ac.uk)
  • 2Geomarine Research, Auckland, New Zealand
  • 3School of Geography, Environment and Earth Sciences, Victoria University of Wellington, New Zealand
  • 4School of Geography, Earth & Environmental Sciences, University of Plymouth, Plymouth, United Kingdom
  • 5Center for Coastal Physical Oceanography, Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA
  • 6Department of River-Coastal Science and Engineering, Tulane University, New Orleans, LA, USA

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 sea level several decimetres below present over the last millennium, before a rapid sea-level rise in the first half of the 20th century that reached maximum rates 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 middle 20th century along the coast of southern New Zealand was primarily driven by regional thermal expansion and ocean dynamics.

How to cite: Garrett, E., Gehrels, R., Hayward, B., Newnham, R., Gehrels, M., Morey, C., and Dangendorf, S.: Late Holocene sea-level change in southern New Zealand , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5675, https://doi.org/10.5194/egusphere-egu22-5675, 2022.