Southern Ocean upwelling, Earth's obliquity, and glacial-interglacial atmospheric CO2 change
Southern Ocean upwelling, Earth's obliquity, and glacial-interglacial atmospheric CO2 change
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DOI：
10.1126/science.abd2115
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发表时间：
2020-12-11
期刊：
影响因子：
56.9
通讯作者：
Haug, Gerald H.
中科院分区：
文献类型：
--
作者：
Ai, Xuyuan E.;Studer, Anja S.;Haug, Gerald H.
先前的研究表明，在晚更新世冰期，南大洋南极区的地表-深部交换在某种程度上减弱了，这减少了深层封存的二氧化碳的泄漏，从而导致冰期大气中二氧化碳水平较低。在这里，从南极区的印度部门的高分辨率氮同位素测量揭示了三种模式的变化，在南西风驱动的上升流，每一个影响大气中的二氧化碳。以前曾提出过两种模式，即全球气候模式和两极跷跷板模式。第三种模式是由地球自转（轴向倾斜）影响的纬向温度梯度引起的，它可以解释冰川开始和冰川消退期间大气二氧化碳滞后于气候的现象。这一气候变化引起的滞后，反过来又使二氧化碳成为晚更新世冰期循环中的延迟气候放大器。
Previous studies have suggested that during the late Pleistocene ice ages, surface-deep exchange was somehow weakened in the Southern Ocean's Antarctic Zone, which reduced the leakage of deeply sequestered carbon dioxide and thus contributed to the lower atmospheric carbon dioxide levels of the ice ages. Here, high-resolution diatom-bound nitrogen isotope measurements from the Indian sector of the Antarctic Zone reveal three modes of change in Southern Westerly Wind-driven upwelling, each affecting atmospheric carbon dioxide. Two modes, related to global climate and the bipolar seesaw, have been proposed previously. The third mode-which arises from the meridional temperature gradient as affected by Earth's obliquity (axial tilt)-can explain the lag of atmospheric carbon dioxide behind climate during glacial inception and deglaciation. This obliquity-induced lag, in turn, makes carbon dioxide a delayed climate amplifier in the late Pleistocene glacial cycles.