Meridional Shifts of the Southern Hemisphere Westerlies During the Early Cenozoic

• Published in: Geophysical Research Letters
• Main Authors: Hongjin Chen, Zhaokai Xu, Germain Bayon, Qingchao Fan, Philip A. E. Pogge von Strandmann, Wei Wang, Tianqi Sun, Tiegang Li
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: early Cenozoic; IODP expedition 369; Mentelle Basin; Southern Hemisphere westerlies; chemical weathering; Geophysics. Cosmic physics; QC801-809; Antarc*; Antarctic; Ice Sheet
• Online Access: https://doi.org/10.1029/2024GL110182; https://doaj.org/article/0c18dfc88ec94f1ea6547fc4c21059f2

Abstract Despite the crucial role of the Southern Hemisphere (SH) westerlies in modulating modern and past climate evolution, little is known about their behavior and possible forcing mechanisms during the early Cenozoic. We probe changes in the hydroclimate of southwest Australia during 62–51 Ma, based on sedimentary proxy records from the International Ocean Discovery Program Site U1514 in the Mentelle Basin. Our results reveal a transition from a less humid climate to wetter conditions at mid–high latitudes starting from the early Eocene, which suggests poleward migration of the SH westerlies. This long‐term trend is punctuated by short‐lived events of aridification during the Mid‐Paleocene Biotic Event and wetter intervals during the Paleocene‐Eocene Thermal Maximum, indicating additional short‐term meridional shifting of the westerlies. We propose that the evolution of SH westerlies was driven by the equator‐to‐pole temperature gradient regulated by global warming and ephemeral growth of the Antarctic ice sheet.