Early Holocene weakening and mid- to late Holocene strengthening of the East Asian winter monsoon

Shugang Kang,Ning Wang,Jinhua Du,Yougui Song,Xulong Wang,Xiaoke Qiang,Jibao Dong,Duo Wang

doi:10.1130/g47621.1

Abstract

AbstractSub-orbital-scale variations of the East Asian winter monsoon (EAWM) and its mechanisms during the Holocene are controversial, partly due to the lack of high-quality records from Chinese loess. Here, we present high-resolution reconstruction of Holocene EAWM intensity based on optically stimulated luminescence dating and grain-size analysis from three loess sections taken from the Chinese Loess Plateau. The EAWM showed a persistent weakening trend during the early Holocene (ca. 11.7–6.5 kyr B.P.) and a strengthening trend during the mid- to late Holocene (since ca. 6.5 kyr B.P.). We propose that this was caused by changes in high-latitude Northern Hemisphere ice volume and middle- to high-latitude Northern Hemisphere atmospheric temperatures, respectively. We also observed an anti-correlation between EAWM and East Asian summer monsoon. Our findings provide a robust solution to the debate regarding Holocene EAWM changes and contribute to the understanding of potential future variations in EAWM intensity.

Highlights

The East Asian winter monsoon (EAWM)determines the strength of cold and dry northwesterly and northeasterly surface flows over East and South Asia during boreal winters (Fig. 1)
We identified an early Holocene persistent weakening of the EAWM and a mid-Holocene continuous strengthening, as demonstrated by records from sections GB and LGG
The EAWM further intensified during the late Holocene and reached a maximum during the Little Ice Age period, as shown by the section WN2 and GB records

Summary

Introduction

The East Asian winter monsoon (EAWM)determines the strength of cold and dry northwesterly and northeasterly surface flows over East and South Asia during boreal winters (Fig. 1). Variations in Holocene EAWM intensity on multiple time scales have been investigated using records including marine sediments (Huang et al, 2011; Zheng et al, 2014; Zhang et al, 2019), lake sediments (An et al, 2011; Wang et al, 2012), loess deposits Loess on the CLP is the ideal and most commonly used material for reconstructing past EAWM intensity (Liu and Ding, 1998). High-resolution loess records of Holocene EAWM intensity are still lacking, with reliable chronology. To reconcile the discrepancies between different records and determine accurate Holocene EAWM intensities, we conducted closely spaced optically stimulated luminescence (OSL) dating and grain-size analysis on three high-resolution loess sections from the CLP to produce a stacked reconstruction of Holocene EAWM intensity. We determined suborbital-scale variations in EAWM intensity and its possible mechanisms and compared these with other records. The relationship between EAWM and EASM intensities was revealed

Methods

Results

Conclusion