EAGER: Characteristic Disruptions of the Marine Carbon Cycle

地球的碳循环由消耗和产生二氧化碳的过程组成。地质记录表明，消费和生产之间的平衡经历了数千年或更长时间的多次中断。这个项目的重点是产生异常高的二氧化碳水平和全球变暖的破坏。以前的工作已经将这些事件与特定来源在合适的气候条件下释放的碳联系在一起。然而，最近的研究表明，这些事件以一种典型的方式发生，与长期气候趋势无关。该项目提出，这种特有的干扰是碳循环中始终活跃的机制的自然结果。该项目将在海洋沉积物的记录中量化这种行为的证据。它还将开发数学模型，以说明这种干扰是如何发生的。为了将这一主题带给更广泛的受众，该项目将在reddit.com的“IAMA”“Ask Me Anything”网站上举行公开问答环节。它还将主办2019年HBO纪录片《火上的冰》的公开放映，该纪录片以相关主题为特色。该项目还将产生新的教育资源，支持研究生的培训，并在新闻媒体上宣传其工作。该项目的总体目标是了解破坏长期碳循环的机制。该项目假设特征突变是通过非线性放大过程发生的。它建议在古气候时间序列中检测这种过程的特征，并通过建立新的模型来解释这些观察到的现象。过去的工作强调了特定沉积碳库在某些个别事件发生中的作用。然而，它也表明，更普遍的破坏路径可能通过不同的气候制度持续存在。该项目力求确定与海洋碳循环的内在非线性动力学有关的这类持久现象的类别。该项目将构建数学模型，展示这是如何发挥作用的，并将寻找他们在过去碳同位素数据波动中预测的证据。这样的理解可能会导致对特定应激源的作用做出新的解释，例如火山活动增强或甲烷释放，作为重大变暖事件的驱动因素。该奖项反映了NSF的法定使命，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，被认为是值得支持的。

Earth's carbon cycle consists of processes that consume and produce carbon dioxide. The geologic record shows that the balance between consumption and production has undergone many disruptions lasting thousands of years or more. This project focuses on disruptions that produce unusually high carbon dioxide levels and global warming. Previous work has related these events to carbon that is released from particular sources under the right climatic conditions. However, recent work suggests these events occur in a typical way independent of longer-term climatic trends. This project proposes that such characteristic disruptions are natural consequences of mechanisms in the carbon cycle that are always active. The project will quantify the evidence of such behavior in records from marine sediments. It will also develop mathematical models to show how such disruptions could arise. To bring this subject to a wide audience, the project will hold public question-and-answer sessions on reddit.com's “IAmA” “Ask me anything” website. It will also host a public screening of the 2019 HBO documentary Ice on Fire, which features related themes. The project will also produce new educational resources, support the training of a graduate student, and publicize its work in the news media.The project's overall goal is to understand mechanisms responsible for disruption of the long-term carbon cycle. The project hypothesizes that characteristic disruptions occur via processes of nonlinear amplification. It proposes to detect signatures of such processes in paleoclimate time series and to explain these observations by construction of new models. Past work has emphasized the role of specific sedimentary carbon reservoirs in generating certain individual events. Yet it also indicates that more general pathways to disruption may have persisted through different climate regimes. The project seeks to identify classes of such persistent phenomena related to intrinsic nonlinear dynamics of the marine carbon cycle. The project will construct mathematical models showing how this could work and will seek evidence of their predictions in past fluctuations in carbon-isotopic data. Such understanding will likely lead to new interpretations of the role of specific stressors, such as enhanced volcanism or the release of methane, as drivers of major warming events. Results will also provide insight into the long-term risks of the human perturbation of the modern carbon cycle.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.