Orbital- and millennial-scale Asian winter monsoon variability across the Pliocene-Pleistocene glacial intensification.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38641605.
- Also identified by DOI 10.1038/s41467-024-47274-9 and PMC identifier 11031568.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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 CO<sub>2</sub> forcing. Northern hemisphere ice sheet expansion, which was accompanied by an atmospheric CO<sub>2</sub> 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-CO<sub>2</sub>) late Pliocene and colder (lower-CO<sub>2</sub>) early Pleistocene, in response to both external astronomical forcing and internal climate dynamics.