Collaborative Research: Evaluating Deep-Sea Ventilation and the Global Carbon Cycle During Early Paleogene Hyperthermals

合作研究：评估古近纪早期高温期间的深海通风和全球碳循环

• 批准号: 1536604
• 负责人: Pincelli Hull
• 金额: $ 11.1万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1536604&HistoricalAwards=false
• 关键词: Collaborative; Research; Evaluating; Deep; Sea

Rapid, short-term global warming events in the Early Paleogene (~65-45 Million years ago) were caused by massive greenhouse gas release into the ocean-atmosphere system. These warming events, called "hyper thermals", had far-reaching effects on the evolution of life on Earth, ecosystems, and the carbon cycle. The most extreme of these events was the Paleocene-Eocene Thermal Maximum (~55.5 Million years ago). Hyperthermals resemble what could happen during anthropogenic climate change, and provide analogs for the effects of greenhouse gas emissions and their long-term effects on life on Earth. By testing earth system interactions during the Paleogene hyperthermals, this interdisciplinary project will provide new insight into global climate-carbon cycle feedbacks and extremes in climate. The research will serve the national interest by improving a widely used Community Earth System Model on high-performance computers, and by synthesizing data and model output with observations from novel isotopic and trace element techniques in marine geology and paleoceanography. Multidisciplinary research and educational activities are integrated and will lead to development and widespread circulation of educational materials on abrupt climate change, thus enhancing training in quantitative science for undergraduate and high school students from diverse backgrounds.Specifically, this collaborative effort involves integration of new biotic, isotopic and trace element proxies with existing data into a state-of-the-art, high-resolution, comprehensive earth system model to test the hypothesis that deep-sea ventilation released a massive amount of carbon from the refractory dissolved organic matter (DOM) pool during hyperthermal events, increasing atmospheric CO2 levels, and thus amplifying climate change through carbon-cycle feedback. The research team will investigate the environmental response (e.g., ocean acidification and deoxygenation) and its impact on pelagic ecosystem structure for three Paleogene hyperthermals with different magnitudes and durations. The project will focus on a key mechanism involving remineralization of organic matter and oxidation of the DOM pool in the ocean, with potentially major implications for future climate evolution, addressing these questions:(1) How might changes in oceanic productivity, organic carbon remineralization, ocean oxygenation, and export efficiency during hyperthermals have contributed to changes in the oceanic dissolved organic matter reservoir? (2) Could DOM release due to enhanced ocean ventilation have been at least a partial cause of Paleogene hyperthermals?(3) What are the implications of Paleogene climate?carbon cycle changes associated with DOM storage and release for future extremes in climate and the environment?New data on planktic and benthic foraminifera, and accumulation of marine barite on the same samples will be obtained and integrated with a large amount of existing data to provide insight into ecosystem-dependent export productivity and remineralization, as well as regionally varying vertical carbon fluxes. Recently gathered data from the equatorial regions will be incorporated in a database to provide initial conditions for the earth system model. The model results will give insight into changes in ocean stratification, vertical carbon gradients, DOM reservoirs, oxygenation, and ecosystem composition during transitions into and out of hyperthermals. In particular, the team will evaluate the possibility of extreme changes in response to ecosystem-related fluctuations in DOM accumulation and subsequent oxidation and emission from the oceans, because the DOM pool is the largest reservoir of easily interchangeable carbon. This mechanism has not been thoroughly explored as a contributor to a transition into a hothouse climate with more extreme weather patterns.

古近纪早期（约 65-4500 万年前）快速、短期的全球变暖事件是由大量温室气体释放到海洋大气系统中引起的。这些变暖事件被称为“高温”，对地球生命的进化、生态系统和碳循环产生了深远的影响。这些事件中最极端的是古新世-始新世最热事件（约 5550 万年前）。高温类似于人为气候变化期间可能发生的情况，并为温室气体排放的影响及其对地球生命的长期影响提供了类比。通过测试古近纪高温期间地球系统的相互作用，这个跨学科项目将为全球气候-碳循环反馈和极​​端气候提供新的见解。该研究将通过在高性能计算机上改进广泛使用的社区地球系统模型，并将数据和模型输出与海洋地质学和古海洋学中的新型同位素和微量元素技术的观测结果相结合，服务于国家利益。多学科研究和教育活动相结合，将导致气候突变教育材料的开发和广泛传播，从而加强对来自不同背景的本科生和高中生的定量科学培训。具体来说，这种合作努力涉及新生物、将现有数据与同位素和微量元素代理集成到最先进的高分辨率综合地球系统模型中，以检验深海通风从难熔溶解有机物 (DOM) 中释放大量碳的假设高温期间的泳池事件，增加大气二氧化碳水平，从而通过碳循环反馈加剧气候变化。研究小组将研究三次不同强度和持续时间的古近纪高温天气的环境响应（例如海洋酸化和脱氧）及其对中上层生态系统结构的影响。该项目将重点研究涉及海洋中有机物再矿化和 DOM 池氧化的关键机制，对未来气候演变具有潜在的重大影响，并解决以下问题：(1) 海洋生产力、有机碳再矿化、高温期间的海洋氧合和输出效率导致了海洋溶解有机物库的变化？ (2) 由于海洋通风增强而导致的 DOM 释放是否至少是古近纪高温的部分原因？(3) 古近纪气候有何影响？与 DOM 储存和释放相关的碳循环变化对未来气候和环境的极端事件?将获得有关浮游和底栖有孔虫的新数据，以及同一样本上海洋重晶石的积累，并将其与大量现有数据相结合，以深入了解依赖于生态系统的出口生产力和再矿化以及区域不同的垂直碳通量。最近从赤道地区收集的数据将被纳入数据库，为地球系统模型提供初始条件。模型结果将深入了解进入和退出高温期间海洋分层、垂直碳梯度、DOM 库、氧合和生态系统组成的变化。特别是，该团队将评估因生态系统相关的 DOM 积累波动以及随后的海洋氧化和排放而发生极端变化的可能性，因为 DOM 池是易于互换的碳的最大储存库。这种机制尚未被彻底探索为向具有更极端天气模式的温室气候过渡的促成因素。