Links Between the Coral δ13C Record of Primary Productivity Variations in the Northern South China Sea and the East Asian Winter Monsoon

The decadal variability of ocean primary productivity (PP) has mainly been studied using relatively short term satellite data, limiting its in-depth analysis. Here, by removing the influence of the C-13 Suess effect, we extract the PP signal on decadal timescales using a record of coral delta C-13 values from the northern South China Sea (NSCS), where the physical-biogeochemical conditions are influenced largely by the winter monsoon. Our results show that the PP in the NSCS increased from 1851 to the 1920s and decreased from the 1920s to 2007, and large superimposed decadal-scale changes were observed. The in-phase relationship observed between the PP reconstruction and winter monsoon records suggests that the changes in the PP in the NSCS are linked to decadal-scale changes in the winter monsoon. Considering that the winter monsoon intensity may weaken in the future under global warming, the PP in the NSCS might decrease in the coming decades.