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.

早第三纪（约6500 - 4500万年前）的快速、短期全球变暖事件是由大量温室气体释放到海洋-大气系统造成的。这些被称为“超热气流”的变暖事件对地球上生命的进化、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-始新世热最大期（约5550万年前）。超高温类似于人类活动引起的气候变化，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似物。通过测试古近纪高温期间地球系统的相互作用，这个跨学科的项目将为全球气候碳循环反馈和极端气候提供新的见解。这项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，并通过将数据和模型输出与海洋地质学和古海洋学中新的同位素和微量元素技术的观测结果相结合，为国家利益服务。多学科的研究和教育活动得到整合，并将导致关于气候突变的教育材料的开发和广泛传播，从而加强对不同背景的本科生和高中生的定量科学培训。具体而言，这一合作努力涉及将新的生物、同位素和微量元素替代物与现有数据整合成一个最先进的、高分辨率的、这是一个综合性地球系统模型，用于检验以下假设：在超高温事件期间，深海通风从难溶有机物池中释放出大量碳，增加大气中的二氧化碳水平，从而通过碳循环反馈放大气候变化。研究小组将调查环境反应（例如，海洋酸化和脱氧）及其对远洋生态系统结构的影响。该项目将侧重于一个关键的机制，涉及海洋中有机物的矿化和DOM池的氧化，对未来气候演变的潜在重大影响，解决这些问题：（1）如何可能在海洋生产力，有机碳矿化，海洋氧化，和输出效率的变化在高温期间有助于海洋溶解有机物水库的变化？(2)由于海洋通风增强而释放的DOM是否至少是古近纪高温流的部分原因？(3)古近纪气候的含义是什么？与DOM储存和释放相关的碳循环变化，以应对未来气候和环境的极端情况？将获得关于南极和底栖有孔虫的新数据，以及相同样品上海洋重晶石的积累，并将其与大量现有数据相结合，以深入了解依赖生态系统的出口生产力和再矿化，以及各区域不同的垂直碳通量。最近从赤道地区收集的数据将纳入数据库，为地球系统模型提供初始条件。该模型的结果将深入了解海洋分层，垂直碳梯度，DOM水库，氧化和生态系统组成的变化，在过渡到和出超高温。特别是，该小组将评估与生态系统有关的DOM积累波动以及随后的海洋氧化和排放引起极端变化的可能性，因为DOM库是最大的易于互换的碳库。这一机制尚未被彻底探索，因为它是向温室气候过渡的一个促成因素，具有更极端的天气模式。