Taiwan has committed to achieving net-zero emissions by 2050. The particulate organic carbon export flux (POC flux) driven by the Biological Carbon Pump (BCP) represents a critical component in marine carbon sink inventories. Although recent studies have reported POC flux data in parts of Taiwan’s Exclusive Economic Zone (EEZ), long-term and systematic observations remain scarce across the vast northern South China Sea and Taiwan’s territorial waters.This study integrates multi-year field measurements collected in the northern South China Sea and the southern territorial waters of Taiwan. The results indicate that the annual average ocean carbon sink in the northern South China Sea is approximately 21.1 Mt-CO₂. Long-term time-series observations further show that when sea surface temperature increases by 1 °C, POC flux decreases by approximately 2–3 mg-C m⁻² d⁻¹, suggesting a 5–7% decline in carbon export efficiency under ocean warming conditions. This reduction is primarily attributed to enhanced stratification caused by seawater warming, which suppresses nutrient transport from subsurface waters to the surface, thereby reducing primary productivity and carbon export efficiency. In addition, this study compares POC flux across the four surrounding marine regions of Taiwan (east, west, south, and north). The average fluxes are 92 ± 33, 54 ± 17, 85 ± 11, and 225 ± 37 mg-C m⁻² d⁻¹, respectively, revealing up to a fourfold regional variation. The highest flux occurs in the northern region, reflecting strong nutrient supply associated with upwelling processes. The eastern and western regions exhibit intermediate fluxes, likely influenced by island effects and continental shelf mixing, whereas the southern region shows relatively lower flux due to oligotrophic water conditions. Based on the measured fluxes in this study, the estimated annual ocean carbon sink within Taiwan’s territorial waters is approximately 8.55 Mt-CO₂ yr⁻¹, substantially higher than the 1.41 Mt-CO₂ yr⁻¹ estimated by global biogeochemical models for the same region. These findings highlight the strong spatial heterogeneity of the biological carbon pump in waters surrounding Taiwan and indicate that global carbon cycle models using uniform parameters may systematically underestimate regional ocean carbon sinks.
 

biological carbon pump,South China Sea,Taiwan