Radiocarbon evidence for the stability of polar ocean overturning during the Holocene
Radiocarbon evidence for the stability of polar ocean overturning during the Holocene
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DOI：
10.1038/s41561-023-01214-2
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发表时间：
2023-06-26
影响因子：
18.3
通讯作者：
Knowles, Timothy D. J.
中科院分区：
文献类型：
--
作者：
Chen, Tianyu;Robinson, Laura F.;Knowles, Timothy D. J.
基于代用物的研究将全新世中后期工业前大气p（CO2）大约20 ppmv的上升与推断的南大洋倾覆和相关生物地球化学变化的增加联系起来。然而，全新世极地海洋翻转和通气的历史仍然知之甚少，在评估温暖气候状态下海洋环流变化与碳循环之间的反馈方面留下了重要的空白。深海放射性碳含量提供了一种通风测量，它对百年到千年时间尺度上的环流变化做出了反应。在这里，我们展示了绝对有年代的深海珊瑚放射性碳记录，这些记录来自位于南美洲和南极洲之间的德雷克海峡，以及冰岛南部的雷克雅内斯山脊，在全新世。我们的数据表明，在我们的采样分辨率下，南极环极水域和北大西洋深水的通风在代理不确定性范围内惊人地不变。我们的研究结果表明，长期的、大规模的极地海洋翻转并没有被干扰到放射性碳可以解决的水平，并且可能不是全新世千年大气pCO(2)演变的原因。相反，在冰川消退之后，水柱内持续的养分和碳再分配，以及陆地有机碳储量的变化，可能调节了这一时期的大气二氧化碳收支。
Proxy-based studies have linked the pre-industrial atmospheric p(CO2) rise of similar to 20 ppmv in the mid- to late Holocene to an inferred increase in the Southern Ocean overturning and associated biogeochemical changes. However, the history of polar ocean overturning and ventilation through the Holocene remains poorly constrained, leaving important gaps in the assessment of the feedbacks between changes in ocean circulation and the carbon cycle in a warm climate state. The deep-ocean radiocarbon content, which provides a measure of ventilation, responds to circulation changes on centennial to millennial time scales. Here we present absolutely dated deep-sea coral radiocarbon records from the Drake Passage, between South America and Antarctica, and Reykjanes Ridge, south of Iceland, over the Holocene. Our data suggest that ventilation in the Antarctic circumpolar waters and North Atlantic Deep Water is surprisingly invariant within proxy uncertainties at our sampling resolution. Our findings indicate that long-term, large-scale polar ocean overturning has not been disturbed to a level resolvable by radiocarbon and is probably not responsible for the millennial atmosphere pCO(2) evolution through the Holocene. Instead, continuous nutrient and carbon redistribution within the water column following deglaciation, as well as changes in land organic carbon stock, might have regulated atmospheric CO2 budget during this period.