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

随着时间的推移，地球的气候发生了变化，在始新世时期（5600万至3400万年前），地球从“温室”状态转变为“冰窖”状态。始新世期间，高纬度地区气温下降导致极地冰川作用开始。这反过来又影响了生物的生存环境。该项目旨在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、海洋学和气候系统之间的相互作用。古生物学和地球化学分析的结合将提供对过去生态和海洋条件的见解；气候模式将用于测试构造、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。这项研究有助于了解大气二氧化碳增加与海洋环流的相互作用。该项目还旨在提高地球科学工作人员的多样性、公平性和包容性，努力针对本科生、研究生、博士后和早期职业教师。研究目的是阐明从始新世温室到渐新世冰窖条件的过程。先前对这种气候变化的解释集中在南极洲，那里的构造构造影响了海洋门户，海洋环流减少了热输送，和/或温室气体的减少促使了冰川作用。研究小组将利用从西摩岛收集的鲨鱼牙齿化石中的地球化学指标（氧和钕同位素组成），重建南极半岛附近的水团、洋流和气候波动。该方法建立在先前鲨鱼古生物学研究的基础上，结合了环境重建的地球化学分析（即温度梯度和海洋环流），并使用地球化学示踪剂模拟新的全球气候模型来测试地球系统动力学的假设。该项目将通过在同位素支持的气候模型模拟中考虑始新世构造配置的实验，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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.