Department of Systems Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
Ocean Resources Research Center for Next Generation, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba, 275-0016, Japan.
Sci Rep. 2017 Sep 12;7(1):11304. doi: 10.1038/s41598-017-11470-z.
Multiple transient global warming events occurred during the early Palaeogene. Although these events, called hyperthermals, have been reported from around the globe, geologic records for the Indian Ocean are limited. In addition, the recovery processes from relatively modest hyperthermals are less constrained than those from the severest and well-studied hothouse called the Palaeocene-Eocene Thermal Maximum. In this study, we constructed a new and high-resolution geochemical dataset of deep-sea sediments clearly recording multiple Eocene hyperthermals in the Indian Ocean. We then statistically analysed the high-dimensional data matrix and extracted independent components corresponding to the biogeochemical responses to the hyperthermals. The productivity feedback commonly controls and efficiently sequesters the excess carbon in the recovery phases of the hyperthermals via an enhanced biological pump, regardless of the magnitude of the events. Meanwhile, this negative feedback is independent of nannoplankton assemblage changes generally recognised in relatively large environmental perturbations.
古近纪早期发生了多次短暂的全球变暖事件。尽管这些被称为超暖事件的事件已经在全球范围内有所报道，但印度洋的地质记录却很有限。此外，与最严重和研究最充分的温室事件——古新世-始新世极热事件相比，从中等程度超暖事件中恢复的过程受到的限制较小。在这项研究中，我们构建了一个新的、高分辨率的深海沉积物地球化学数据集，该数据集清晰地记录了印度洋中多次始新世超暖事件。然后，我们对高维数据矩阵进行了统计分析，并提取了与超暖事件生物地球化学响应相对应的独立成分。无论事件的规模如何，生产力反馈通常通过增强的生物泵来控制和有效地隔离超暖事件恢复阶段的多余碳，这是一个负反馈过程。同时，这种负反馈与在相对较大的环境扰动中普遍观察到的纳米浮游生物组合变化无关。
