本文转自《Nature》杂志发表的论文“CO2 storage and release in the deep Southern Ocean on millennial to centennial timescales”

作者：J. W. B. Rae, A. Burke, L. F. Robinson, J. F. Adkins, T. Chen, C. Cole, R. Greenop, T. Li, E. F. M. Littley, D. C. Nita, J. A. Stewart & B. J. Taylor 

日期：20181024 

页码：Naturevolume 562, pages569–573 (2018)

原文链接：https://www.nature.com/articles/s41586-018-0614-0

Abstract

The cause of changes in atmospheric carbon dioxide (CO2) during the recent ice ages is yet to be fully explained. Most mechanisms for glacial–interglacial CO2 change have centred on carbon exchange with the deep ocean, owing to its large size and relatively rapid exchange with the atmosphere1. The Southern Ocean is thought to have a key role in this exchange, as much of the deep ocean is ventilated to the atmosphere in this region2. However, it is difficult to reconstruct changes in deep Southern Ocean carbon storage, so few direct tests of this hypothesis have been carried out. Here we present deep-sea coral boron isotope data that track the pH—and thus the CO2 chemistry—of the deep Southern Ocean over the past forty thousand years. At sites closest to the Antarctic continental margin, and most influenced by the deep southern waters that form the ocean’s lower overturning cell, we find a close relationship between ocean pH and atmospheric CO2: during intervals of low CO2, ocean pH is low, reflecting enhanced ocean carbon storage; and during intervals of rising CO2, ocean pH rises, reflecting loss of carbon from the ocean to the atmosphere. Correspondingly, at shallower sites we find rapid (millennial- to centennial-scale) decreases in pH during abrupt increases in CO2, reflecting the rapid transfer of carbon from the deep ocean to the upper ocean and atmosphere. Our findings confirm the importance of the deep Southern Ocean in ice-age CO2 change, and show that deep-ocean CO2 release can occur as a dynamic feedback to rapid climate change on centennial timescales.

近期冰河期间大气二氧化碳（CO2）变化的原因尚未得到充分解释。冰川 - 间冰期二氧化碳变化的大多数机制都集中在与深海的碳交换上，因为它的大尺寸和与大气1的相对快速交换。南大洋被认为在这次交换中起着关键作用，因为大部分深海通向该地区的大气2。然而，很难重建南大洋深海碳储量的变化，因此很少对该假设进行直接测试。在这里，我们提供深海珊瑚硼同位素数据，追踪过去四万年来南海深海的pH值和二氧化碳化学成分。在最接近南极大陆边缘的地点，并且受到形成海洋较低倾覆细胞的深海南部水域的影响最大，我们发现海洋pH值与大气CO2之间存在密切关系：在低CO2浓度间隔期间，海洋pH值较低，反映增强海洋碳储存;在二氧化碳上升的时间间隔内，海洋pH值上升，反映了海洋中碳向大气的损失。相应地，在较浅的地点，我们发现二氧化碳突然增加时pH值迅速下降（千年到百年规模），反映了碳从深海到上层海洋和大气的快速转移。我们的研究结果证实了南大洋深冰对冰期二氧化碳变化的重要性，并表明深海二氧化碳的释放可以作为对百年时间尺度快速气候变化的动态反馈。

详细原文请链接：https://www.nature.com/articles/s41586-018-0614-0