Millennial climate oscillations regulated organic carbon yields from a young orogen during the Last Glacial

Approximately one-third of the global terrestrial organic carbon (OC) flux to the oceans originates from active orogens, which play a vital role in regulating atmospheric CO₂ concentrations and global climate through their high flux and burial efficiency in the oceans. However, the relationship between long-term climate change and OC yield from active orogens remains less well understood. Here, we analyse a long core from the Zhuoshui River Delta using sedimentary facies, organic geochemistry, and geochronology to evaluate the impact of millennial climate oscillations on OC yields from the Taiwan orogen during the Last Glacial. Our results show lower OC yields during warm–humid interstadials compared to cold–arid stadials, as stronger physical erosion and higher sediment discharge during warmer periods favoured the deposition of coarser, low-OC sediments in the fluvial channel. The mean OC accumulation rate in the delta during the Last Glacial is estimated as 44.2 ± 48.8 % of the recent value, indicating a diminished carbon sink effect in response to colder and drier climate. Our findings highlight the potential negative feedback of OC cycling in small mountainous river systems on long-term climate change.