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。鉴于需要对未来海平面变化进行高保真的定量预测，必须了解与人为气候变化(即亚千年)节奏相符的时间尺度上的海平面变化；同时，要从机制上全面理解短期变化所依据的海平面变化的较低频率(即轨道尺度)基线特征的信息。这种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遇到的气候边界条件。因此，该项目的目的是在比现代更温暖的气候下，准确地破译与人类有关的(即亚千年)时间尺度上的海平面变化。选定的目标区间为上新世晚期至更新世早期(~3.35至2.05Myr，海洋同位素MG1至78期)，因为它捕捉到了与理解近期气候变化有关的全部气候边界条件。将通过基于氧同位素、镁/钙比和应用于热带太平洋(ODP849站点)底栖有孔虫的新型“丛集同位素”古测温的创新综合地球化学方法，产生准确、定量的海平面估计。这一方法是向更传统的基于氧同位素和镁/钙的海平面估算迈出的关键一步。值得注意的是，这将有助于解决不同深度时间(即&gt；500 KYR)海平面重建之间的实质性不一致，因为它们尚可使用。由于新数据集的时间分辨率很高，该项目还将首次对晚上新世/早更新世冰川的内部解剖与相对了解的晚更新世冰川的结构进行深入比较。

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.