Quantitative reconstruction of sea-level dynamics for the Late Pliocene to Early Pleistocene (Marine Isotope Stages MG1–78): An integrated approach using oxygen isotopes, Mg/Ca ratios and "clumped isotopes"

海平面上升是人为气候变化的一个组成部分，具有极高的社会相关性。鉴于对未来海平面变化进行高保真定量预估的需要，必须了解与人为气候变化速度（即次千年）相称的时间尺度上的海平面变率；同时，需要关于短期变率基础上海平面变化的较低频率（即轨道尺度）基线特征的资料，以便全面了解其机制。这些信息可以从地球历史的时间间隔中获得，这些时间间隔包括在不久的将来将要遇到的气候边界条件。因此，这个项目的目的是在比现代更温暖的气候下，准确地破译与人类相关的（即次千年）时间尺度上的海平面变化。选择晚上新世至早更新世（~3.35 ~ 2.05 Myr，海洋同位素阶段MG1 ~ 78）为目标层段，因为它捕获了与了解近未来气候变化相关的全范围气候边界条件。通过一种创新的综合地球化学方法，基于氧同位素、Mg/Ca比率和应用于热带太平洋底栖有孔虫的新型“块状同位素”古温学，将产生准确的定量海平面估计（ODP Site 849）。这种方法代表着相对于更传统的基于氧同位素和Mg/ ca的海平面估计迈出了关键的一步。值得注意的是，它将有助于解决不同深度时间（即bbb500kyr）海平面重建之间的实质性不一致性，因为它们仍然可用。由于新数据集的高时间分辨率，该项目还将首次允许在晚上新世/早更新世冰川的内部解剖与相对较好理解的晚更新世冰川的结构之间进行深入比较。

Sea-level rise represents a component of anthropogenic climate change with exceptionally high societal relevance. In light of the need for high-fidelity, quantitative projections of future sea-level change, it is mandatory to understand sea-level variability at timescales that do justice to the tempo of anthropogenic climate change (i.e., sub-millennial); at the same time, information on the lower-frequency (i.e., orbital-scale) baseline characteristics of sea-level change underlying the short-term variability is required for a full mechanistic understanding. Such information can be obtained from time intervals of Earths history that comprise climatic boundary conditions as they are to be encountered in the near future. Therefore, this project aims at accurately deciphering sea-level variability on human-relevant (i.e., sub-millennial) timescales under a warmer-than-modern climate. The selected target interval is the Late Pliocene to Early Pleistocene (~3.35 to 2.05 Myr, Marine Isotope Stages MG1 to 78) because it captures the full range of climatic boundary conditions relevant for understanding near-future climate change. Accurate, quantitative sea-level estimates will be generated through an innovative, integrated geochemical approach based on oxygen isotopes, Mg/Ca ratios and novel "clumped-isotope" paleothermometry applied to benthic foraminifera from the tropical Pacific Ocean (ODP Site 849). This approach represents a critical step forward with respect to more conventional oxygen-isotope- and Mg/Ca-based sea-level estimates. Notably, it will help resolving the substantial inconsistencies between the different deep-time (i.e., >500 kyr) sea-level reconstructions as they are yet available. Owing to the high temporal resolution of the new datasets, the project will also allow for the first time an in-depth comparison between the internal anatomy of a Late Pliocene/Early Pleistocene glacial and the structure of the relatively well-understood Late Pleistocene glacials.