Understanding ocean carbon uptake mechanisms during glacial-interglacial cycles

自从科学家们第一次发现冰河时期的二氧化碳含量很低以来，他们就一直在提出理论来解释其中的原因。许多研究考察了各个机制在将二氧化碳隔离在海洋中的作用，还有一些研究则仔细研究了在冰河时代结束时二氧化碳是如何排出海洋的。由于地球系统模型还不能模拟整个冰期-间冰期循环期间的二氧化碳变化，因此汇集新数据变得越来越重要，既可以量化海洋的环境变化，也可以评估模型如何很好地识别冰川气候变化中最重要的机制。******我的研究项目集中在地球进入冰河时代时海洋的命运，以及不同的反馈在冰川循环的不同阶段如何发挥主导作用。我的长期目标是汇集多种古海洋学证据，以更全面地了解地球进入冰期循环时海洋是如何变化的，并利用这种综合来测试哪些海洋学过程对大气二氧化碳的封存起着最重要的作用。我的研究计划中的三个项目旨在重建冰川期不同阶段的海洋物理和生物地球化学的不同方面；这些方面包括灰尘沉积、海洋生产力、海冰覆盖和深海温度。我的方法将把全球环境数据汇编——提供新颖和创新的多行数据的时空比较——与对海洋沉积物样本的新分析——结合起来，以填补关于海洋如何变化的知识方面的现有空白。该项目将为2名博士、1名硕士和5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、粉尘沉积和南大洋海冰覆盖变化的多个基准数据集，并明确关注以前没有研究过的早期和中期冰川时期。这些数据将有利于气候建模者，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，在过去地球经历不同边界条件的时期模拟碳-气候反馈。此外，当这些项目结合在一起时，将提供对假设的全面检验，以检验大规模气候波动期间海洋环流的变化如何与海冰覆盖、粉尘的铁施肥、海洋生产力和海洋碳封存的变化联系起来。

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.