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

随着温室气体浓度上升导致世界变暖，地球系统正朝着前所未有的气候状态发展，挑战社会适应能力。然而，地球的历史为未来几十年的全球变暖提供了可能的类似物。其中包括始新世早期（约50 Ma）的气候状态，根据目前的温室气体排放轨迹，可能会在2150年达到。因此，对始新世气候和生态系统的研究可以为他们可能在不久的将来对应的状态和动态提供关键的见解。这样一个“从过去的教训”可以微调模型的预测，并最终支持我们的能力，以适应未来。一个特殊的沉积档案，研究早到中始新世气候变化是由玛珥湖沉积物的梅塞尔化石坑，联合国教科文组织世界遗产，位于达姆施塔特，西南德国。虽然梅塞尔以其保存完好的动物群和植物群遗迹而闻名，这些遗迹提供了对古近纪陆地生态系统的罕见观察，但其沉积物代表了在地质学上最近的地球温室期（约48 Ma）期间短期气候动力学的独特档案。以前的研究已经证明了这种沉积档案对气候变化的敏感性（例如，通过花粉分析）的轨道时间尺度。由于在梅塞尔发现的沉积物显示出（最有可能）年度分层，因此，鉴于存在极高分辨率的代用数据，它们进一步允许了解短期（即十年期到潜在的季节性）气候变率。在这里，我们建议生成地球化学数据，通过高分辨率（1毫米= ~7年）的梅塞尔FB 2001岩芯XRF核心扫描破译在始新世温室世界在中欧的水文变化。这些数据有可能产生洞察古环境和古气候演变的梅塞尔在前所未有的十年亚轨道时间的时间分辨率。因此，新的数据将用于构建一个高分辨率的天文学调整的年龄模型，改进目前基于低分辨率花粉数据的年龄模型。我们将进一步开发一个干湿指数，用于解释（i）在未来全球变暖情景中类似于预期的条件下的气候趋势和动态，以及（ii）限制气候对进化模式的影响，如在Messel恢复的独特化石记录所揭示的那样。

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.