Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan.
Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Sci Rep. 2019 May 10;9(1):6449. doi: 10.1038/s41598-019-42573-4.
Further understanding of past climate requires a robust estimate of global ice volume fluctuations that in turn rely on accurate global sea-level reconstructions. An advantage of Marine Isotope Stage 2 (MIS 2) is the availability of suitable material for radiocarbon dating to allow comparison of sea-level data with other paleoclimatic proxies. However, the number and accuracy of sea-level records during MIS 2 is currently lacking. Here we present the history of MIS 2 eustatic sea-level change as recorded in the Bonaparte Gulf, northwestern Australia by reconstructing relative sea level and then modeling glacial isostatic adjustment. The isostatically-corrected global sea-level history indicates that sea-level plateaued from 25.9 to 20.4 cal kyr BP (modeled median probability) prior reaching its minimum (19.7 to 19.1 cal kyr BP). Following the plateau, we detect a 10-m global sea-level fall over ~1,000 years and a short duration of the Last Glacial Maximum (global sea-level minimum; 19.7 to 19.1 cal kyr BP). These large changes in ice volume over such a short time indicates that the continental ice sheets never reached their isostatic equilibrium during the Last Glacial Maximum.
进一步了解过去的气候需要对全球冰量波动进行稳健估计，而这反过来又依赖于准确的全球海平面重建。海洋同位素阶段 2 (MIS 2) 的一个优势是有合适的物质可用于放射性碳测年，从而可以将海平面数据与其他古气候替代指标进行比较。然而，目前 MIS 2 期间的海平面记录的数量和准确性都不足。在这里，我们通过重建相对海平面，然后对冰川均衡调整进行建模，来记录澳大利亚西北部波拿巴湾 MIS 2 期间的海平面变化历史。经均衡调整的全球海平面历史表明，海平面在达到最小值（19.7 至 19.1 千年前）之前，从 25.9 至 20.4 千年前稳定在同一水平。在这个平台期之后，我们检测到全球海平面在大约 1000 年内下降了 10 米，并且末次冰盛期（全球海平面最低值；19.7 至 19.1 千年前）的持续时间很短。在如此短的时间内，冰量发生如此大的变化表明，在末次冰盛期期间，大陆冰盖从未达到其均衡平衡状态。
