Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes.
Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes.
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DOI：
10.1038/ncomms11539
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发表时间：
2016-05-17
影响因子：
16.6
通讯作者：
Waelbroeck C
中科院分区：
文献类型：
--
作者：
Gottschalk J;Skinner LC;Lippold J;Vogel H;Frank N;Jaccard SL;Waelbroeck C
在最后一次冰川时期和冰川消融期间，千年尺度的气候变化伴随着大气中二氧化碳的快速变化，这些变化仍然无法解释。虽然强调了南大洋作为海洋-大气二氧化碳交换“控制阀”的作用，但这种作用的确切性质，特别是物理作用(例如，海洋动力学和大气-海洋气体交换)与生物过程(例如，出口生产力)的相对贡献，仍然很少受到制约。在这里，我们结合了南极以下大西洋的底层水[O2]、出口产量和14C通风年龄的重建，并表明，在最后一次冰川和去冰期期间，大气中的二氧化碳脉冲始终伴随着碳生物输出的减少和来自南方的水团的深海通风的增加。这些发现表明，南大洋的“有机碳泵”如何通过物理和生物过程的协同作用，严格控制大气中的二氧化碳，进而控制全球气候。对于过去千年尺度的大气二氧化碳变化，许多解释的直接替代证据仍然很少。在这里，作者们表明，在过去的65,000年里，南大洋深处呼吸碳储存效率的变化与大气中二氧化碳的变化有关。
Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean–atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air–sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and 14C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes. Direct proxy evidence for the many explanations for past millennial-scale atmospheric CO2 changes remains scarce. Here, the authors show that changes in the efficiency of respired carbon storage in the deep Southern Ocean were linked to variations in atmospheric CO2 over the last 65,000 years.