Understanding ocean carbon uptake mechanisms during glacial-interglacial cycles

自从科学家第一次发现冰河时期二氧化碳水平较低以来，他们一直在提出理论来解释其中的原因。许多研究考察了单个机制在海洋中隔离二氧化碳方面的作用，还有一些研究仔细研究了二氧化碳在冰河时代结束时是如何离开海洋的。由于地球系统模型尚未模拟整个冰川-间冰期周期内二氧化碳的变化，收集新的数据以量化海洋环境变化以及评估模型在多大程度上能够很好地确定冰川气候变化的最重要机制变得越来越重要。 我的研究项目关注的是随着地球进入冰河时代，海洋的命运，以及不同的反馈如何在冰川周期的不同阶段发挥主导作用。我的长期目标是汇集多条古海洋学证据，以创建一幅更完整的地球进入冰川周期时海洋变化的图景，并利用这一综合来测试哪些海洋过程对大气二氧化碳的封存做出了最重要的贡献。我的研究计划中的三个项目旨在重建冰川时期不同阶段的海洋物理和生物地球化学的不同方面；这些方面包括尘埃沉积、海洋生产力、海冰覆盖和深海温度。我的方法将结合全球环境数据汇编-提供多行数据的新颖和创新的空间和时间比较-与对海洋沉积物样本的新分析-以填补关于海洋如何变化的现有知识空白。这些项目将为两名博士、一名硕士和五名本科生提供重要的跨学科培训。 这项研究的一个关键成果是，它将提供海洋温度、海洋生产力、尘埃沉积和南大洋海冰覆盖变化的多个基准数据集，明确侧重于以前从未研究过的冰川早期和中期时间段。这些数据将有利于气候模型师，他们希望评估地球系统模型的技能，如加拿大的UVic地球系统模型，模拟过去地球经历不同边界条件时的碳-气候反馈。此外，当这些项目结合在一起时，将提供一个全面的假说测试，研究大规模气候波动期间海洋环流的变化如何与海冰覆盖的变化、尘埃中的铁肥、海洋生产力和海洋碳封存有关。

Ever since scientists first discovered that carbon dioxide levels were low during ice ages, they have been proposing theories to understand why. Many studies have examined the role of individual mechanisms in sequestering carbon dioxide in the ocean, and others have closely examined how carbon dioxide exits the ocean at the end of an ice age. As Earth system models have yet to simulate carbon dioxide changes over a full glacial-interglacial cycle, it becomes increasingly important to bring together new data, both to quantify environmental changes of the ocean, as well as to evaluate how well models can identify the most important mechanisms in glacial climate change. My research program focuses on the fate of the ocean as the Earth enters an ice age, and how different feedbacks play dominant roles during different stages of a glacial cycle. My long-term objective is to bring together multiple lines of paleo-oceanographic evidence to create a more complete picture of how the ocean changes as the Earth enters a glacial cycle, and to use this synthesis to test which oceanographic processes are the most important contributors to the sequestration of atmospheric carbon dioxide. The three projects in my research program are designed to reconstruct different aspects of ocean physics and biogeochemistry during different stages of a glacial period; these aspects include dust deposition, ocean productivity, sea ice cover, and deep-ocean temperatures. My approach will combine global environmental data compilation - to provide novel and innovative spatial and temporal comparisons of multiple lines of data - with new analyses on marine sediment samples - to fill existing gaps in knowledge about how the ocean is changing. The projects will provide important interdisciplinary training to two doctoral, one Masters, and five undergraduate students. One key outcome of this research is that it will provide multiple benchmark datasets of changes in ocean temperature, marine productivity, dust deposition, and Southern Ocean sea-ice cover, with explicit focus on the early- and mid-glacial time periods that have not previously been studied. These data will benefit climate modelers who wish to evaluate the skill of Earth system models, such as Canada's UVic Earth System Model, in simulating carbon-climate feedbacks during past time periods when the Earth experienced different boundary conditions. Furthermore, when brought together, these projects will provide a comprehensive test of hypotheses examining how the ocean circulation changes during large-scale climate fluctuations are linked with changes in sea ice cover, iron fertilization from dust, marine productivity, and ocean carbon sequestration.