Collaborative Research: Integrating Eocene Shark Paleoecology and Climate Modeling to reveal Southern Ocean Circulation and Antarctic Glaciation

地球的气候随着时间的推移而变化，在始新世(5600万年前到3400万年前)，从温室到冰室的条件发生了转变。始新世期间，高纬度地区温度向较低温度的转变导致了极地冰川的开始。这反过来又影响了生物体的环境。该项目希望通过对过去探险中收集的鲨鱼牙齿化石进行化学分析，揭示南极洲始新世生物、海洋和气候系统之间的相互作用。古生物和地球化学分析的结合将提供对过去生态和海洋条件的洞察；将应用气候模型来测试构造、温室气体浓度和海洋环流在这段时间内对环境变化的作用。这项研究有助于理解大气二氧化碳增加和海洋环流之间的相互作用。该项目还致力于改善地球科学劳动力的多样性、公平性和包容性，努力面向本科生、研究生、博士后和早期职业教师。研究目标是阐明从始新世温室到渐新世冰库条件的过程。以前对这种气候变化的解释集中在南极洲，那里的构造配置影响了海洋门户，海洋环流减少了热量传输，和/或温室气体减少促进了冰川作用。该研究小组将使用从西摩岛收集的鲨鱼牙齿化石的地球化学指标(氧和钕同位素组成)来重建南极半岛附近的水团、洋流和气候波动。该方法建立在以前鲨鱼古生物学研究的基础上，纳入了用于环境重建(即温度梯度和海洋环流)的地球化学分析，并利用带有地球化学示踪剂的新型全球气候模型模拟来检验关于地球系统动力学的假说。该项目将通过在启用同位素的气候模型模拟中考虑始新世构造配置的实验来提高全球气候建模能力。将始新世气候模拟的地球化学结果与鲨鱼牙齿的经验记录进行比较，将揭示始新世南极气候变化的核心过程和机制。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Earth's climate has changed through time and during the Eocene Epoch (56 to 34 million years ago) there was a transition from 'greenhouse' to 'icehouse' conditions. During the Eocene, a shift to cooler temperatures at high latitudes resulted in the inception of polar glaciation. This in turn affected the environment for living organisms. This project looks to uncover the interaction between biological, oceanographic, and climate systems for the Eocene in Antarctica using chemical analysis of fossil shark teeth collected during past expeditions. The combination of paleontological and geochemical analyses will provide insight to the past ecology and ocean conditions; climate models will be applied to test the role of tectonics, greenhouse gas concentration and ocean circulation on environmental change during this time period. The study contributes to understanding the interaction of increased atmospheric carbon dioxide and ocean circulation. This project also seeks to improve diversity, equity, and inclusion within the geosciences workforce with efforts targeted to undergraduate, graduate, postdoctoral, and early career faculty.The research goal is to elucidate the processes leading from the Eocene greenhouse to Oligocene icehouse conditions. Previous explanations for this climate shift centers on Antarctica, where tectonic configurations influenced oceanic gateways, ocean circulation reduced heat transport, and/or greenhouse gas declines prompted glaciation. The team will reconstruct watermass, current, and climate fluctuations proximal to the Antarctic Peninsula using geochemical indicators (oxygen and neodymium isotope composition) from fossil shark teeth collected from Seymour Island. The approach builds on previous shark paleontological studies, incorporates geochemical analyses for environmental reconstruction (i.e., temperature gradients and ocean circulation), and tests hypotheses on Earth System dynamics using novel global climate model simulations with geochemical tracers. This project will advance global climate modeling capabilities with experiments that consider Eocene tectonic configuration within isotope-enabled climate model simulations. A comparison of geochemical results from Eocene climate simulations and empirical records of shark teeth will reveal processes and mechanisms central to the Eocene Antarctic climatic shift.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.