The variation of the East Asian summer monsoon on multi-centennial scale during 8.3–2.9 ka BP

As a key component of the global climate system, the Asian summer monsoon (ASM) exhibits variability on centennial timescales that remains poorly understood. Based on high-precision U-Th dating and multi-proxy analyses (δ¹⁸O, δ¹³C and Mg/Ca) of stalagmite YK1306 from Yangkou Cave, Chongqing, southwestern China, this study reconstructs a hydroclimate variability for southwestern China during 8.3–2.9 ka BP, and elucidate the spatial and temporal characteristics of centennial-scale climate variability in the East Asian summer monsoon (EASM) region during this period. The multi-proxy records indicated ∼500-year cycles of hydroclimatic variability in southwestern China during 8.3–2.9 ka BP, and suggest relatively stable climatic conditions across the EASM region during 6.5–4.8 ka BP. On centennial timescales, hydroclimatic changes in southwestern China are broadly synchronous with those in northern China during the mid-Holocene. Records of Antarctic meltwater, the Intertropical Convergence Zone (ITCZ), and hydroclimatic variations in southwestern China exhibit a common ∼500-year periodicity. Model simulations indicate that freshwater input into the Southern Ocean enhances the meridional thermal gradient between the hemispheres, strengthening cross-equatorial flow and driving a northward shift of the ITCZ. Therefore, Antarctic meltwater, by modulating the Atlantic Meridional Overturning Circulation (AMOC) and ITCZ, contributed to increased centennial-scale climate variability during 8.3–6.5 ka BP and 4.8–2.9 ka BP. This study proposes that coupled ocean–atmosphere interactions between the Northern and Southern Hemispheres drive centennial-scale oscillations of the ASM, offering important insights into regional hydro-ecological evolution and societal development at centennial timescales.