Recently, a study led by Dr. Weiyi Sun and his team from the School of Geography at Nanjing Normal University was published in SCIENCE CHINA Earth Sciences . The team used simulations from the isotope-enabled Community Earth System Model-Last Millennium Ensemble (iCESM-LME), together with δ 18 O reconstructions to investigate decadal variability of the East Asian monsoon.
Earlier studies have emphasized local precipitation amount, seasonal effects, and moisture transport pathways have influenced on decadal variability of δ ¹⁸O p . In particular, the mechanisms controlling δ ¹⁸O p variability—especially related to moisture sources and transport pathways—remain insufficiently understood.
The study revealed that δ ¹⁸O p share a quasi-11-year cycle as the leading mode of decadal variability across the monsoon region. Spatially, δ ¹⁸O p exhibits a coherent regional pattern, while precipitation itself shows a tripolar wet–dry–wet mode. By comparing the solar-forcing-only experiment with the control experiment reflecting internal variability, the researchers confirmed that external solar forcing plays a dominant role in driving the quasi-11-year δ ¹⁸O p cycle.
Water-tagging experiments further demonstrated that enhanced solar irradiance modulates a La Niña–like SST anomalies, which enhances the Walker Circulation. This leads to enhanced upstream convection over the Maritime Continent and a greater contribution of moisture from the equatorial Pacific, resulting in lower δ 18 O p values across the monsoon region. Our findings suggest that the quasi-11-year δ 18 O p cycle primarily reflects shifts in moisture sources driven by solar activity.
This study provides new insights into the decadal variability of δ 18 O p over the past millennium, promotes comparability between model simulations and proxy records, and holds important scientific value for understanding monsoon dynamics and projecting future changes in the East Asian monsoon.
See the article:
Da C, Wang X, Sun W, Liu J, Ning L, Chen G. 2025. Decadal variability in δ 18 O over the East Asian monsoon region responding to solar activity over the last millennium. Science China Earth Sciences, 68(9): 2853–2866, https://doi.org/10.1007/s11430-025-1644-0
Science China Earth Sciences
Computational simulation/modeling