Presentation Information
[ACG68-P13]Effects of Coastal Erosion and Seafloor Sediment on Arctic Ocean CO2 Uptake
*YUANXIN ZHANG1, EIJI WATANABE2, SAYAKA YASUNAKA1,3 (1.Tohoku University, 2.Japan Agency for Marine-Earth Science and Technology, 3.Advanced Institute for Marine Ecosystem Change (WPI-AIMEC))
Keywords:
Coastal Erosion,Seafloor Sediment,Arctic Ocean,Air-Sea CO2 exchange
Arctic shelf seas absorb a substantial amount of atmospheric CO2 owing to their extensive open-water area and high primary productivity. Accelerating coastal erosion and sediment resuspension deliver terrestrial and benthic biogeochemical materials that can modify the seawater carbonate system and alter air–sea CO2 exchange. To quantify these impacts, we conducted multi-decadal sensitivity experiments for 1979–2018 using a pan-Arctic sea ice–ocean biogeochemistry model (COCO & Arctic NEMURO-C), incorporating observation-based biogeochemical inputs from coastal erosion and seafloor sediment.
The simulation results indicate that coastal erosion and seafloor sediment substantially elevates surface seawater pCO2 over Arctic shelf seas. In the East Siberian and Laptev Seas, air–sea CO2 fluxes shift from net uptake in the baseline simulation to net outgassing, suggesting a reversal from an atmospheric CO2 sink to a source. Sediment-derived biogeochemical fluxes exert a more delayed influence, emerging on multi-decadal timescales. Moreover, sediment impacts exhibit remarkable regional contrasts, with much larger effects in the East Siberian Sea than in the Chukchi Sea, likely reflecting the role of ocean current and lateral carbon transport.
Under ongoing climate warming, permafrost thaw, and enhanced benthic carbon release, the Arctic shelf seas may increasingly lose their capacity to mitigate rising atmospheric CO2, with important implications for future Arctic carbon–climate feedbacks.
The simulation results indicate that coastal erosion and seafloor sediment substantially elevates surface seawater pCO2 over Arctic shelf seas. In the East Siberian and Laptev Seas, air–sea CO2 fluxes shift from net uptake in the baseline simulation to net outgassing, suggesting a reversal from an atmospheric CO2 sink to a source. Sediment-derived biogeochemical fluxes exert a more delayed influence, emerging on multi-decadal timescales. Moreover, sediment impacts exhibit remarkable regional contrasts, with much larger effects in the East Siberian Sea than in the Chukchi Sea, likely reflecting the role of ocean current and lateral carbon transport.
Under ongoing climate warming, permafrost thaw, and enhanced benthic carbon release, the Arctic shelf seas may increasingly lose their capacity to mitigate rising atmospheric CO2, with important implications for future Arctic carbon–climate feedbacks.