美国俄勒冈州立大学Wendt, Kathleen A.研究团队报道，海因里希冰期南大洋驱动大气二氧化碳的多年代际上升。这一研究成果发表在2024年5月13日出版的国际学术期刊《美国科学院院刊》上。

据研究人员介绍，北大西洋地区的最后一个冰期被寒冷的间歇所打断，最终导致了大规模的冰山喷发事件。这些被称为海因里希冰期的寒冷间隔与全球气候突变有关。

本研究展示了来自南极西部冰盖的二氧化碳值，以多年代际尺度分辨率将海因里希冰期冰芯划分为2至5。研究结果揭示了每个海因里希冰期内大气中CO₂浓度的多年代际尺度的跳跃。最大的变化幅度(55±10y内为14.0±0.8ppm)，发生在海因里希冰期4期间。大气CO₂的突然上升与大气CH₄的跳跃以及多个南极冰芯中水等值线的突然变化同时发生，后者表明南极洲和南大洋的蒸汽源区都在快速变暖。这些快速变化的同步性表明，在风的驱动下，南大洋中相对温暖、富含碳的海水上涌，这可能与南半球西风向极地加强有关。

研究人员利用同位素支持的大气环流模式，发现观测到的南极水等值线的变化可以用南大洋突然和广泛的变暖来解释。该研究工作为南大洋对大气环流变化的多年代际到世纪尺度的响应提供了证据，证明了在人类时间尺度上，南大洋生物地球化学和环流的动态变化的潜力。此外，它还表明，南大洋人为的CO₂吸收在今天和未来可能会随着西风带向极地加强而减弱。

附：英文原文

Title: Southern Ocean drives multidecadal atmospheric CO₂ rise during Heinrich Stadials

Author: Wendt, Kathleen A., Nehrbass-Ahles, Christoph, Niezgoda, Kyle, Noone, David, Kalk, Michael, Menviel, Laurie, Gottschalk, Julia, Rae, James W. B., Schmitt, Jochen, Fischer, Hubertus, Stocker, Thomas F., Muglia, Juan, Ferreira, David, Marcott, Shaun A., Brook, Edward, Buizert, Christo

Issue&Volume: 2024-5-13

Abstract: The last glacial period was punctuated by cold intervals in the North Atlantic region that culminated in extensive iceberg discharge events. These cold intervals, known as Heinrich Stadials, are associated with abrupt climate shifts worldwide. Here, we present CO₂ measurements from the West Antarctic Ice Sheet Divide ice core across Heinrich Stadials 2 to 5 at decadal-scale resolution. Our results reveal multi-decadal-scale jumps in atmospheric CO₂ concentrations within each Heinrich Stadial. The largest magnitude of change (14.0 ± 0.8 ppm within 55 ± 10 y) occurred during Heinrich Stadial 4. Abrupt rises in atmospheric CO₂ are concurrent with jumps in atmospheric CH₄ and abrupt changes in the water isotopologs in multiple Antarctic ice cores, the latter of which suggest rapid warming of both Antarctica and Southern Ocean vapor source regions. The synchroneity of these rapid shifts points to wind-driven upwelling of relatively warm, carbon-rich waters in the Southern Ocean, likely linked to a poleward intensification of the Southern Hemisphere westerly winds. Using an isotope-enabled atmospheric circulation model, we show that observed changes in Antarctic water isotopologs can be explained by abrupt and widespread Southern Ocean warming. Our work presents evidence for a multi-decadal- to century-scale response of the Southern Ocean to changes in atmospheric circulation, demonstrating the potential for dynamic changes in Southern Ocean biogeochemistry and circulation on human timescales. Furthermore, it suggests that anthropogenic CO₂ uptake in the Southern Ocean may weaken with poleward strengthening westerlies today and into the future.

DOI: 10.1073/pnas.2319652121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2319652121