Dai Yuhao, Yu Jimin
Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.
Australian Centre for Excellence in Antarctic Science, Australian National University, Canberra, ACT, Australia.
Nat Commun. 2025 Mar 18;16(1):2665. doi: 10.1038/s41467-025-57677-x.
As a critical region regulating air-sea gas exchanges, the polar Southern Ocean has important implications for deglacial atmospheric CO rises. However, proxy data evidence is sparse to evaluate the respective roles of Southern Ocean biological and physical dynamics in affecting past air-sea CO exchanges due to longstanding challenges in obtaining carbonate materials to reconstruct surface conditions in this region. Here, we circumvent these challenges by constraining polar Southern Ocean surface-water conditions based on preformed deep-water properties derived from paired carbonate ion-phosphate-oxygenation reconstructions during the last deglaciation. We show that polar Southern Ocean carbon losses coincided with increased deep-ocean preformed nutrient concentrations, highlighting reduced biological carbon utilization as a key process for deglacial CO outgassing. By comparing total carbon losses with those attributable to biological processes, we further show that enhanced physically-driven air-sea gas exchanges in the polar Southern Ocean strongly drove CO outgassing towards the end of the last deglaciation.
作为调节海气气体交换的关键区域，南大洋极地地区对冰消期大气二氧化碳上升具有重要影响。然而，由于在获取碳酸盐材料以重建该地区表面条件方面长期存在挑战，用于评估南大洋生物和物理动力学在影响过去海气二氧化碳交换中各自作用的代用数据证据稀少。在此，我们通过基于末次冰消期期间从成对的碳酸根离子 - 磷酸根 - 氧合作用重建中得出的预制深水属性来约束南大洋极地地区的表层水条件，从而规避了这些挑战。我们表明，南大洋极地地区的碳损失与深海预制营养物浓度增加同时发生，突出了生物碳利用减少是冰消期二氧化碳脱气的关键过程。通过将总碳损失与生物过程导致的碳损失进行比较，我们进一步表明，末次冰消期末期南大洋极地地区物理驱动的海气气体交换增强有力地推动了二氧化碳脱气。
