Bihemispheric Warming in the Miocene Climatic Optimum as Seen From the Danish North Sea
Bihemispheric Warming in the Miocene Climatic Optimum as Seen From the Danish North Sea
复制标题
DOI：
10.1029/2020pa003935
复制
发表时间：
2020-10-01
影响因子：
3.5
通讯作者：
Sliwinska, Kasia K.
中科院分区：
文献类型：
--
作者：
Herbert, Timothy D.;Rose, Rebecca;Sliwinska, Kasia K.
中新世见证了气候的重大变化。海洋氧同位素记录是我们对时间间隔的最佳单一连续表示，它包含了大的变化，表明南极洲冰川作用和/或深海温度的实质性变化，其中最耗尽的同位素组成的间隔发生在类似于18至13.9 Ma（中新世中期气候最佳[MCO]）之间。在这里，我们给出了一份烯烃不饱和度估算记录，该记录来自于钻穿海洋沉积物的井眼，这些沉积物跨越了大部分中新世，温度大约为北纬56度。中新世重建的海洋温度比现在高出20摄氏度。最大值出现在MCO时。这一记录与北大西洋其他地点公布的不连续烯烃结果惊人地相似。与南半球一样，北大西洋的海洋温度梯度与今天相比非常低。我们的研究结果表明，MCO是一个全球最高温度，并将南极的部分消冰和随后的“制冷”与全球强迫过程联系起来。然而，14 ~ 10 Ma的海洋降温幅度较小，表明南极东部冰量与全球温度之间存在高度非线性（阈值）关系。
The Miocene epoch witnessed major changes in climate. The marine oxygen isotope record, our best single continuous representation of the time interval, contains large shifts indicating substantial changes in the glaciation of Antarctica and/or deep ocean temperatures, with the interval of the most depleted isotopic composition occurring between similar to 18 and 13.9 Ma (mid-Miocene Climatic Optimum [MCO]). We present here a record of alkenone unsaturation estimates from a borehole penetrating marine sediments spanning most of the Miocene at similar to 56 degrees N. Marine temperatures reconstructed for the Miocene are up to 20 degrees C warmer than present day. A maximum occurs at the time of the MCO. The record is strikingly similar to discontinuous alkenone results published from other North Atlantic sites. As in the southern hemisphere, ocean temperature gradients were extraordinarily low in the North Atlantic in comparison to today. Our findings suggest that the MCO was a global temperature maximum and link the partial deglaciation of the Antarctic and subsequent "refrigeration" to a global forcing process. However, the small magnitude of the ocean cooling from similar to 14 to 10 Ma suggests a highly nonlinear (threshold) relationship between East Antarctic ice volume and global temperature.