Paleoclimate reconstructions from sediment core MD01-2378

On the basis of the radiocarbon (14C) plateau-tuning method a new age model for Timor Sea Core MD01-2378 was established. It revealed a precise centennial-scale phasing of climate events in the ocean, cryo-, and atmosphere during the last deglacial and provides important new insights into causal linkages controlling events of global climate change. At Site MD01-2378 reservoir ages of surface waters dropped from 1600 yr prior to 20 cal ka to 250-500 yr after 18.8 cal ka. This evidence was crucial for generating a high-resolution age model for deglacial events in the Indo-Pacific Warm Pool. Sea-surface temperatures (SST) started to change near 18.8 cal ka, that is ~500 yr after the start of, presumably northern hemispheric, deglacial melt and sea level rise as shown by the benthic foraminiferal oxygen isotope ratio (d18O). However, the SST rise occurred 500-1000 yr prior to the onset of deglacial Antarctic warming and the first major rise in atmospheric carbon dioxide at about 18 ka. The increase in SST may partly reflect reduced seasonal upwelling of cold subsurface waters along the eastern margin of the Indian Ocean, which is reflected by a doubling of the thermal gradient between the sea surface and the thermocline, a halving of chlorin productivity from 19 to 18.5 cal ka, and in particular, by the strong decrease in surface water reservoir ages. Two significant increases in deglacial Timor Sea surface salinities from 19-18.5 and 15.5-14.5 cal ka, may partly reflect the deglacial increase in the distance of local river mouths, partly an inter-hemispheric millennial-scale see-saw in tropical monsoon intensity, possibly linked to a deglacial increase in the dominance of Pacific El Niño regimes over Heinrich stadial 1.基于放射性碳（radiocarbon, ¹⁴C）高原调谐法，本研究建立了帝汶海岩芯MD01-2378的全新年代模型。该模型精准揭示了末次冰消期期间海洋、冰冻圈与大气中气候事件的百年尺度相位关系，为阐明控制全球气候变化事件的因果关联提供了重要新认知。 MD01-2378站位的表层水储库年龄从20校准千年（cal ka）前的1600年，降至18.8校准千年（cal ka）后的250~500年。这一证据对构建印太暖池内冰消期事件的高分辨率年代模型至关重要。 海表温度（sea-surface temperatures, SST）的变化起始于18.8校准千年，即约在北半球冰消期融水与海平面上升启动后约500年，该结论可通过底栖有孔虫氧同位素比值（δ¹⁸O）得到验证。 然而，海表温度的升温较南极冰消期首次显著增温以及大气二氧化碳浓度在约18校准千年时的首次大幅上升早500~1000年发生。 海表温度的升高可能部分反映了印度洋东部沿岸冷次表层水季节性上升流的减弱，这一现象可通过以下指标佐证：海表与温跃层间的温度梯度翻倍、叶绿素生产力在19~18.5校准千年间减半，尤其表层水储库年龄的显著降低。 帝汶海冰消期表层盐度在19~18.5校准千年与15.5~14.5校准千年出现两次显著升高，这可能部分反映了当地河口距海距离的冰消期增大，同时也可能与热带季风强度的千年尺度半球间跷跷板现象有关——该现象或与冰消期太平洋厄尔尼诺（El Niño）状态相较于海因里希冷期1（Heinrich stadial 1）占据主导地位的变化相关。