Rainfall amplified sea-level control on silicate weathering in the Indo-Pacific Convergence Zone during Quaternary glacials

The Indo-Pacific Convergence Zone is a key carbon sink via silicate weathering, yet its glacial-interglacial carbon dioxide consumption remains unclear. Here we reconstruct silicate weathering fluxes over the past 700,000 years by combining the global geochemical numerical model GEOCLIM with machine learning algorithms to constrain silicate weathering history in the Indo-Pacific Convergence Zone. Our results show that during glacial periods, weathering fluxes peaked at approximately 1.86 × 1012 moles per year, drawing down about 9.3 ppmv of carbon dioxide. Exposure of continental shelves during low sea levels raised glacial weathering by 33%, but high-frequency positive rainfall anomalies amplified this increase by 54–130% (approximately 9.2–13.7 ppmv carbon dioxide). This underscores how sea-level change and hydrology control tropical shelf weathering. Our study provides critical insights into past climatic transitions, emphasizing the Indo-Pacific Convergence Zone’s role in regulating the global carbon cycle and offering constraints for future climate projections. During glacial periods, silicate weathering fluxes in the Indo-Pacific Convergence Zone were 33% higher compared to interglacial periods, with rainfalls amplifying it to 54–130%, according to numerical simulation of silicate chemical weathering.