The Magnitude of Surface Ocean Acidification and Carbon Release During Eocene Thermal Maximum 2 (ETM-2) and the Paleocene-Eocene Thermal Maximum (PETM)
The Magnitude of Surface Ocean Acidification and Carbon Release During Eocene Thermal Maximum 2 (ETM-2) and the Paleocene-Eocene Thermal Maximum (PETM)
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DOI：
10.1029/2019pa003699
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发表时间：
2020-02-01
影响因子：
3.5
通讯作者：
Zachos, J. C.
中科院分区：
文献类型：
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作者：
Harper, D. T.;Honisch, B.;Zachos, J. C.
始新世热峰2（ETM-2; 54.1 Ma）是第二大始新世超高温。与古新世-始新世热盛期（PETM）一样，ETM-2的特征是大量的碳排放和几度全球变暖，因此可以作为评估CO2快速排放对海洋碳酸盐化学，生物群和气候影响的案例研究。ETM-2的海相碳酸盐记录保存得比PETM的好，这是由于碳酸盐溶解作用较弱。然而，到目前为止，这种碳循环扰动的幅度还没有得到很好的限制。在这里，我们提出了ETM-2的第一个表面海洋酸化记录，基于来自两个中纬度ODP站点（北太平洋1210和东南大西洋1265）的混合层浮游有孔虫中的稳定硼同位素记录，这表明保守的最小全球海洋表面酸化为-0.20 +0.12/-0.13 pH单位。使用这些pH值和温度的估计值作为碳循环模型模拟的约束条件，我们得出结论，在ETM-2期间，在15至25 kyr的时间内释放的C的总质量可能在2，600至3，800 Gt C之间，这大于先前基于其他观测结果（即，稳定碳同位素和碳酸盐补偿深度）。
Eocene Thermal Maximum 2 (ETM-2; 54.1 Ma) was the second largest Eocene hyperthermal. Like the Paleocene-Eocene Thermal Maximum (PETM), ETM-2 was characterized by massive carbon emissions and several degrees of global warming and thus can serve as a case study for assessing the impacts of rapid CO2 emissions on ocean carbonate chemistry, biota, and climate. Marine carbonate records of ETM-2 are better preserved than those of the PETM due to more subdued carbonate dissolution. As yet, however, the magnitude of this carbon cycle perturbation has not been well constrained. Here, we present the first records of surface ocean acidification for ETM-2, based on stable boron isotope records in mixed-layer planktic foraminifera from two midlatitude ODP sites (1210 in the North Pacific and 1265 in the SE Atlantic), which indicate conservative minimum global sea surface acidification of -0.20 +0.12/-0.13 pH units. Using these estimates of pH and temperature as constraints on carbon cycle model simulations, we conclude that the total mass of C, released over a period of 15 to 25 kyr during ETM-2, likely ranged from 2,600 to 3,800 Gt C, which is greater than previously estimated on the basis of other observations (i.e., stable carbon isotopes and carbonate compensation depth) alone.