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<p>As a subsystem of the Asian summer monsoon, East Asian summer monsoon (EASM) plays a key role in climatic changes in the Northern Hemisphere. In the core region of EASM, however, few terrestrial paleoclimate records have been utilized to examine EASM characteristics except for oxygen isotope (<i>δ</i><sup>18</sup>O) records from stalagmites since the last glacial period. Consequently, the driving mechanisms of EASM evolution have remained unresolved. Here, we present the longest and highest-resolution drilling core from Lake Chaohu, located in the Yangtze River Basin within the core region of the Asian monsoon, which uniquely records EASM variability since 36 ka (thousands of years before 1950 AD) on a millennial timescale. The sedimentary geochemistry, grain size, and magnetic susceptibility of the core are used to reconstruct East Asian summer monsoon index (EASMI). These records document a relatively weak EASM during the period of 35.7–13.5 ka, a high EASMI from 13.5 to 8.4 ka, and a gradually decreasing EASMI after 8.4 ka. Notably, the Heinrich and Younger Dryas events are well documented in the sediment, reflecting significant climate variability. These results are remarkably consistent with <i>δ</i><sup>18</sup>O records from Greenland ice cores and the Indian summer monsoon; however, some discrepancies are observed when compared with Chinese stalagmite records. By contrasting these findings with global hydroclimatic records, we demonstrate that changes in EASM on a millennial scale were driven by high- and low-latitude forcings on different periods. During the last glaciation, the influences of the ice sheet activity in northern high-latitude area and the westerlies dominated. In the last deglaciation, the Atlantic Meridional Overturning Circulation (AMOC) had an important effect on EASM by regulating the climate of low-latitude Indo-Pacific region. During the Holocene, low-latitude summer insolation emerged as the key driver of EASM, indicating a strong linkage of EASM to orbital forcings, which changed in concert with the modern EASM circulation. Our findings highlight the dynamic nature of the monsoon system throughout different climatic periods.</p>

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High- and low-latitude forcings on East Asian summer monsoon variability over the past 36,000 years: A high-resolution record from Lake Chaohu, eastern China

  • 期刊论文

  • 发表日期：

    2025年5月19日

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  • Shuguang Lu,
  • Li Wu,
  • Chunmei Ma,
  • Junwu Shu,
  • Houchun Guan,
  • Xiaoyu Han,
  • Wenjing Luo,
  • Ziyi Xu,
  • Boshi Liu,
  • Wentian Cai,
  • Yang Zhang,
  • Qiwen Wei

摘要

As a subsystem of the Asian summer monsoon, East Asian summer monsoon (EASM) plays a key role in climatic changes in the Northern Hemisphere. In the core region of EASM, however, few terrestrial paleoclimate records have been utilized to examine EASM characteristics except for oxygen isotope (δ18O) records from stalagmites since the last glacial period. Consequently, the driving mechanisms of EASM evolution have remained unresolved. Here, we present the longest and highest-resolution drilling core from Lake Chaohu, located in the Yangtze River Basin within the core region of the Asian monsoon, which uniquely records EASM variability since 36 ka (thousands of years before 1950 AD) on a millennial timescale. The sedimentary geochemistry, grain size, and magnetic susceptibility of the core are used to reconstruct East Asian summer monsoon index (EASMI). These records document a relatively weak EASM during the period of 35.7–13.5 ka, a high EASMI from 13.5 to 8.4 ka, and a gradually decreasing EASMI after 8.4 ka. Notably, the Heinrich and Younger Dryas events are well documented in the sediment, reflecting significant climate variability. These results are remarkably consistent with δ18O records from Greenland ice cores and the Indian summer monsoon; however, some discrepancies are observed when compared with Chinese stalagmite records. By contrasting these findings with global hydroclimatic records, we demonstrate that changes in EASM on a millennial scale were driven by high- and low-latitude forcings on different periods. During the last glaciation, the influences of the ice sheet activity in northern high-latitude area and the westerlies dominated. In the last deglaciation, the Atlantic Meridional Overturning Circulation (AMOC) had an important effect on EASM by regulating the climate of low-latitude Indo-Pacific region. During the Holocene, low-latitude summer insolation emerged as the key driver of EASM, indicating a strong linkage of EASM to orbital forcings, which changed in concert with the modern EASM circulation. Our findings highlight the dynamic nature of the monsoon system throughout different climatic periods.