NOAA/WDS Paleoclimatology - EPICA Dronning Maud Land Ice Core 10-51 KYrBP d18O Data

Precise knowledge of the phase relationship between climate changes in the two hemispheres is a key for understanding the Earth's climate dynamics. For the last glacial period, ice core studies have revealed strong coupling of the largest millennial-scale warm events in Antarctica with the longest Dansgaard-Oeschger events in Greenland through the Atlantic meridional overturning circulation. It has been unclear, however, whether the shorter Dansgaard-Oeschger events have counterparts in the shorter and less prominent Antarctic temperature variations, and whether these events are linked by the same mechanism. Here we present a glacial climate record derived from an ice core from Dronning Maud Land, Antarctica, which represents South Atlantic climate at a resolution comparable with the Greenland ice core records. After methane synchronization with an ice core from North Greenland, the oxygen isotope record from the Dronning Maud Land ice core shows a one-to-one coupling between all Antarctic warm events and Greenland Dansgaard-Oeschger events by the bipolar seesaw. The amplitude of the Antarctic warm events is found to be linearly dependent on the duration of the concurrent stadial in the North, suggesting that they all result from a similar reduction in the meridional overturning circulation.

精准掌握南北半球气候变化的相位关系，是理解地球气候动力学机制的关键所在。在末次冰期，冰芯（ice core）研究已揭示：南极地区规模最大的千年尺度暖事件，与格陵兰地区最长的丹斯果-奥什格尔事件（Dansgaard-Oeschger events），通过大西洋经向翻转环流（Atlantic meridional overturning circulation）实现了强耦合。然而，此前仍存在两个未解问题：其一，规模更小的丹斯果-奥什格尔事件是否对应南极地区规模更小、信号更弱的温度变化；其二，两类事件是否通过相同机制实现关联。本研究基于南极毛德皇后地（Dronning Maud Land）的一支冰芯，重建了一套冰期气候记录，该记录能够反映南大西洋气候状况，其时间分辨率可与格陵兰冰芯记录相媲美。通过与北格陵兰冰芯的甲烷序列进行年代校准后，毛德皇后地冰芯的氧同位素记录（oxygen isotope record）显示：所有南极暖事件与格陵兰丹斯果-奥什格尔事件均通过双极跷跷板（bipolar seesaw）机制实现了一一对应的耦合关系。研究还发现，南极暖事件的振幅与北半球同期冰阶（stadial）的持续时长呈线性相关，这表明两类事件均源自经向翻转环流的类似强度减弱过程。