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"

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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.