Hindcasting the Ocean radiocarbon history of the past 25,000 years

了解和模拟在最后一个冰河时代结束时大气中二氧化碳水平上升的幅度和时间一直是地球科学研究界面临的一个重大挑战。与此同时，要对气候变化做出明智的长期社会反应，就需要详细了解各种时间尺度上的气候-碳循环反馈。该项目通过深入研究过去25 000年来海洋碳循环的演变及其与海洋环流变化和碳库交换的关系来应对这些挑战。从该项目中获得的信息将有助于评估地球系统模式在过去、现在和未来气候条件下的性能。使用一系列具有时变边界条件的瞬态地球系统模型实验，研究小组将确定重现现有古海洋示踪剂的冰消期海洋环流情景，特别关注放射性碳。通过将其他年龄示踪剂纳入拟议的模型模拟中，将测试各种基于放射性碳的“通风”年龄方法的保真度，例如投影年龄和底栖生物-浮游生物年龄差方法。拟议的数值实验将提供更深入的物理见解的气候-碳循环反馈的动态。具体问题包括：1。大气放射性碳产生率随时间变化的信号是如何“传播”到深海的？2.在末次冰期终止期间海洋环流的变化如何影响世界海洋放射性碳异常的三维结构？3.冰川期下北冰洋的潜在碳储存能力是多少？4.在第一个终端和进入全新世的过程中，储层年龄的空间和时间变化是什么？

Understanding and simulating the magnitude and timing of the rise in atmospheric carbon dioxide levels at the end of the last ice age has been a major challenge for the Earth Science research community. At the same time, a well-informed long-term societal response to climate changes requires a detailed understanding of climate-carbon cycle feedbacks on a variety of timescales. This project addresses these challenges through an in-depth study of the evolution of the marine carbon cycle over the past 25,000 years and its relation to ocean circulation changes and carbon reservoir exchanges. The information gained from this project will be beneficial for assessing the performance of earth system models under past, present and future climate conditions. Using a series of transient earth system model experiments with time-varying boundary conditions, the research team will identify deglacial ocean circulation scenarios that reproduce the existing paleoceanographic tracers, with special focus on radiocarbon. By including other age tracers into the proposed model simulations, the fidelity of various radiocarbon-based "ventilation" age methods, such as the projection age and the benthic-planktonic age difference method will be tested. The proposed numerical experiments will provide deeper physical insights into the dynamics of climate-carbon cycle feedbacks. Specific questions that will be addressed include: 1. How did the time-varying signal of atmospheric radiocarbon production rates "propagate" into the deep ocean? 2. How did ocean circulation changes during the last glacial termination affect the three-dimensional structure of radiocarbon anomalies in the world's oceans? 3. What is the potential carbon storage capacity of the Arctic Ocean under glacial periods?4. What is the spatial and temporal variability of reservoir ages over the course of Termination 1 and into the Holocene?