147 Climate, Ocean and Environmental Changes Through Earth History: From Marine and Terrestrial Proxies to Model Assessments (Posters)

This session brings together marine and terrestrial proxies and modelling to reconstruct rapid ocean, environment, and climate events, and shifts between long-term climate/ocean/environment states, within the context of normal variability throughout Earth history.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Understanding the Orbital to Millennial-Scale Variability of the Southern Hemisphere Westerly Winds: Biomarker Reconstructions from the North Island of New Zealand

Paper number: 147-13
Program: Technical Sessions
Time: 8:45 AM – 8:45 AM

Authors

Abstract

From heat transfer to storm regulation, the Southern Hemisphere westerly winds (SHWW) play a key role in the global climate by balancing climate perturbations between the high and low latitudes. On glacial timescales, the latitudinal position of the SHWW has major implications for Southern Ocean CO2 storage, making them an essential feedback mechanism for past changes in global climate. While studies have suggested that the westerlies vary in position and intensity in response to orbital and millennial-scale forcings, climate models and proxy data disagree about the nature of the SHWW responses to orbital forcings and glacial boundary conditions. Our knowledge of the SHWW is further limited due to the lack of well-dated, unambiguous proxy indicators. To address these uncertainties, we generated a continuous 130-kyr long, high-resolution proxy reconstruction of the SHWW from Orakei Basin and Lake Pupuke, located on the North Island of New Zealand, using the hydrogen isotope composition of sedimentary leaf waxes as a proxy for Southern Hemisphere moisture sources associated with changes in the position of the SHWW. We complement these data with temperature reconstructions using the MBT’5ME index. The temperature record shows a rapid cooling of 3oC transitioning out of the Eemian, then remains relatively stable throughout most of the last glacial, with minimum temperatures centered on ca. 70-ka and during the Last Glacial Maximum. On orbital timescales, temperature and dDwax variations are broadly synchronous with Antarctic temperature changes, reflecting the influence of large-scale, global climate processes on the position and strength of SHWW. However, on millennial timescales and during the deglaciation, their agreement weakens, suggesting important differences in the controls of the SHWW and temperature on these timescales. These findings highlight the complex, time-scale dependent nature of the SHWW, emphasizing their role in modulating regional hydroclimate and contributing to global climate feedbacks across glacial-interglacial timescales.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414829

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.