Digging into Eocene hothouse climate variability: Elemental signals derived from X-ray fluorescence scanning of Messel sediment cores

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As the world warms due to rising greenhouse gas concentrations, the Earth system moves toward climate states without historic precedent, challenging societal adaptation. However, Earth’s history offers possible analogues for the warming world of the coming decades. These include the climatic state of the early Eocene (~50 Ma), which based on current greenhouse-gas emission trajectories, will likely be reached by 2150. Hence, the study of Eocene climates and ecosystems can provide critical insight into the states and dynamics of their likely near-future counterparts. Such a ‘lesson from the past’ can be instrumental for fine-tuning model predictions and ultimately support our abilities for adaption to the future.An exceptional sedimentary archive to study early to middle Eocene climate variability is presented by the maar-lake sediments of the Messel fossil-pit, UNESCO world heritage site located near Darmstadt, SW Germany. While Messel is famous for its exceptionally well-preserved faunal and floral remains that provide a rare look into terrestrial ecosystems of the Paleogene, its sediments represent a unique archive for short-term climate dynamics operating during the geologically most recent greenhouse period of the Earth at around 48 Ma. Previous studies have demonstrated the sensitivity of this sedimentary archive to climate changes (e.g., via pollen analysis) on orbital time scales. As the sediments recovered at Messel exhibit (most likely) annual lamination, they further allow for insights into short-term (i.e. decadal down to potentially seasonal) climate variability, given the presence of extremely highly resolved proxy data.However, analysis of its geochemical changes allowing insights in much higher temporal resolution are yet unavailable. Here we propose to generate geochemical data via high-resolution (1 mm = ~7 yr) XRF core scanning of the Messel FB2001 drill core to decipher the hydrological variability in Central Europe during the Eocene greenhouse world. Such data have the potential to yield insight into the paleoenvironmental and paleoclimatic evolution of Messel in unprecedented decadal to sub-orbital time temporal resolution. As such, the new data will be used to construct a high-resolution, astronomically tuned age model, improving the present age model that is based on low-resolution pollen data. We will further develop a wet-dry index that will be utilized to decipher (i) climate trends and dynamics under conditions resembling those expected during future global warming scenarios and (ii) constraining the climatic impact on evolutionary patterns as revealed by the unique fossil record recovered at Messel.