Orbital- and millennial-scale Asian winter monsoon variability across the Pliocene-Pleistocene glacial intensification

Hong Ao; Diederik Liebrand; Mark J Dekkers; Andrew P Roberts; Tara N Jonell; Zhangdong Jin; Yougui Song; Qingsong Liu; Qiang Sun; Xinxia Li; Chunju Huang; Xiaoke Qiang; Peng Zhang

doi:10.1038/s41467-024-47274-9

Orbital- and millennial-scale Asian winter monsoon variability across the Pliocene-Pleistocene glacial intensification

Nat Commun. 2024 Apr 19;15(1):3364. doi: 10.1038/s41467-024-47274-9.

Authors

Hong Ao^{1

2}, Diederik Liebrand³, Mark J Dekkers⁴, Andrew P Roberts⁵, Tara N Jonell⁶, Zhangdong Jin^{7

8}, Yougui Song⁷, Qingsong Liu⁹, Qiang Sun¹⁰, Xinxia Li^{7

11}, Chunju Huang¹¹, Xiaoke Qiang⁷, Peng Zhang^{7

8}

Affiliations

¹ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China. aohong@ieecas.cn.
² Laoshan Laboratory, Qingdao, China. aohong@ieecas.cn.
³ Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK.
⁴ Paleomagnetic Laboratory 'Fort Hoofddijk', Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands.
⁵ Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.
⁶ School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK.
⁷ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China.
⁸ Laoshan Laboratory, Qingdao, China.
⁹ Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
¹⁰ College of Geology and Environment, Xi'an University of Science and Technology, Xi'an, China.
¹¹ School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan, China.

Abstract

Intensification of northern hemisphere glaciation (iNHG), ~2.7 million years ago (Ma), led to establishment of the Pleistocene to present-day bipolar icehouse state. Here we document evolution of orbital- and millennial-scale Asian winter monsoon (AWM) variability across the iNHG using a palaeomagnetically dated centennial-resolution grain size record between 3.6 and 1.9 Ma from a previously undescribed loess-palaeosol/red clay section on the central Chinese Loess Plateau. We find that the late Pliocene-early Pleistocene AWM was characterized by combined 41-kyr and ~100-kyr cycles, in response to ice volume and atmospheric CO₂ forcing. Northern hemisphere ice sheet expansion, which was accompanied by an atmospheric CO₂ concentration decline, substantially increased glacial AWM intensity and its orbitally oscillating amplitudes across the iNHG. Superposed on orbital variability, we find that millennial AWM intensity fluctuations persisted during both the warmer (higher-CO₂) late Pliocene and colder (lower-CO₂) early Pleistocene, in response to both external astronomical forcing and internal climate dynamics.