Eccentricity-paced geomagnetic field and monsoon rainfall variations over the last 870 kyr.

Zhou, Weijian; Kong, Xianghui; Paterson, Greig A; Sun, Youbin; Wu, Yubin; Ao, Hong; Xian, Feng; Du, Yajuan et al. · Proc Natl Acad Sci U S A · 2023

basic_science · Level V

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Abstract

Whether there are links between geomagnetic field and Earth's orbital parameters remains unclear. Synchronous reconstructions of parallel long-term quantitative geomagnetic field and climate change records are rare. Here, we present <sup>10</sup>Be-derived changes of both geomagnetic field and Asian monsoon (AM) rainfall over the last 870 kyr from the Xifeng loess-paleosol sequence on the central Chinese Loess Plateau. The <sup>10</sup>Be<i><sub>GM</sub></i> flux (a proxy for geomagnetic field-induced <sup>10</sup>Be production rate) reveals 13 consecutive geomagnetic excursions in the Brunhes chron, which are synchronized with the global records, providing key time markers for Chinese loess-paleosol sequences. The <sup>10</sup>Be-derived rainfall exhibits distinct ~100 kyr glacial-interglacial cycles, and superimposed precessional (~23 kyr) cycles that match with those in Chinese speleothem δ<sup>18</sup>O record. We find that changes in the geomagnetic field and AM rainfall share a common ~100 kyr cyclicity, implying a likely eccentricity modulation of both the geomagnetic field and climate.