Interhemispheric monsoon response to bipolar forcing during Heinrich Stadial 4

This Supporting Information document provides additional details and data supporting the findings of the study titled “Interhemispheric Monsoon Response to Bipolar Forcing during Heinrich Stadial 4.” The dataset and methods described herein are derived from speleothem samples collected in Shennong Cave (117°15′N, 28°42′E; ~383 m above sea level) is located in Jiangxi Province, southeastern China. This Supporting Information document includes Texts S1 to S3, Figures S1 to S8, and Tables S1 to S2, providing detailed laboratory methods, climatic controls, and breakpoint determination methodologies. Text S1 outlines the laboratory methods, including 230Th dating, stable isotope analysis, fluorescence imaging, and annual lamina counting. Text S2 discusses the climatic controls of the Indian vs. East Asian monsoons, highlighting the influence of sea surface temperatures (SST) in the tropical Indian Ocean on the Indian Summer Monsoon (ISM) and the modulation of the East Asian Summer Monsoon (EASM) by the Western Pacific Subtropical High (WPSH), the Intertropical Convergence Zone (ITCZ), and ENSO variability. Text S3 describes the methodology for breakpoint determination using the BREAKFIT algorithm, which identifies shifts in paleoclimate records following the onset of Heinrich Stadial 4 (HS4). Figures S1 to S8 illustrate key results, including fluorescence images, age models, and climatic reconstructions, while Tables S1 and S2 provide comprehensive datasets, including 230Th dating results, δ¹³C, δ¹⁸O.