Collaborative Research: Atmospheric CO2 and the Relationship to Millennial Changes in Atmospheric and Oceanic Circulation in the Eastern Equatorial Pacific Ocean over the Past 100

合作研究：大气CO2及其与过去100年东赤道太平洋大气和海洋环流千年变化的关系

• 批准号: 1803933
• 负责人: Matthew Schmidt
• 金额: $ 27.44万
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1803933&HistoricalAwards=false
• 关键词: Collaborative; Research; Atmospheric; CO2; Relationship

To understand future climate change, we must know how climate varied in the past. One of the biggest unknowns about past climate is the origin of atmospheric carbon dioxide (CO2) variability over global warm-cold cycles. This project will address potential causes of the varying atmospheric carbon dioxide by focusing on changes in the efficiency of fertilization of the surface ocean, and how, and if, that is related to changes in the deep-ocean. Furthermore, the research will investigate both the "how" of varying carbon dioxide with the "where", namely the Eastern Equatorial Pacific (EEP), an important region of the world ocean where, today, significant CO2 is exhaled to the atmosphere and the greatest rates of phytoplankton growth are found. The project will contribute to an improved understanding of global climate change and important Earth systems connected to the tropical Pacific Ocean. On the broadest of levels, understanding the past dynamics of Earth's carbon cycle is of fundamental importance to inform and guide societal policy-making in an increasing CO2 world. The project will support the educational and professional development of graduate and undergraduate students and results will be incorporated into the curriculum of undergraduate and graduate classes. In addition, a series of YouTube videos will be developed that are aimed at communicating the importance of how past climate variability informs us about climate's future variability and its potential impact on our lives.The project seeks to answer questions related to: 1) where and how atmospheric carbon dioxide was sequestered from the atmosphere, or ventilated from the ocean, on millennial timescales, and 2) how these carbon dynamics are related to both changes in atmospheric and oceanic circulation over the last glacial period and into the deglacial and Holocene. To address these objectives, an integrated suite of multiple proxies will be measured in two high accumulation rate sediment cores previously collected from the EEP. These proxies include: authigenic uranium as a proxy for bottom water oxygenation and radiocarbon ages of benthic foraminifera as a proxy for changes in the age of deep water in the EEP, 231Pa/230Th ratios and excess Ba fluxes as proxies for productivity, excess 230Th-derived 232Th flux as a proxy for dust flux, B/Ca ratios in planktonic foraminifera as a proxy for carbonate ion concentration of surface water, and Nd and Pb isotope ratios as a proxy for the provenance of the dust source of the detrital component of the sediment and, therefore, an index of Intertropical Convergence Zone migration. By investigating the storage of a respired carbon pool in the deep ocean during cold periods of the last glacial period (i.e., from ~71,000 to 14,000 years ago), in conjunction with probing how this storage relates to changes in export production and potential iron fertilization, the research will shed light on the mechanistic links between ocean (stratification/ventilation) and atmospheric (wind belt shifts) circulation and the modification of atmospheric CO2 levels.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.

要了解未来的气候变化，我们必须了解过去的气候变化。 关于过去气候的最大未知数之一是全球冷暖循环中大气二氧化碳（CO2）变化的起源。该项目将通过关注表层海洋施肥效率的变化，以及它如何以及是否与深海变化相关，来解决大气二氧化碳变化的潜在原因。此外，该研究还将调查二氧化碳的“方式”和“地点”的变化，即东赤道太平洋（EEP），这是世界海洋的一个重要区域，今天，大量的二氧化碳被排放到大气中，并且发现浮游植物生长速度最快。该项目将有助于加深对全球气候变化和与热带太平洋相连的重要地球系统的了解。从最广泛的层面来看，了解地球碳循环过去的动态对于在二氧化碳排放不断增加的世界中为社会决策提供信息和指导至关重要。该项目将支持研究生和本科生的教育和专业发展，其成果将纳入本科生和研究生课程。此外，还将制作一系列 YouTube 视频，旨在传达过去气候变化如何让我们了解未来气候变化及其对我们生活的潜在影响的重要性。该项目旨在回答以下相关问题：1) 地点和地点大气中的二氧化碳如何在千年时间尺度上从大气中被隔离，或从海洋中排出，以及2）这些碳动态如何与末次冰河期以及冰消期和冰消期的大气和海洋环流的变化相关。全新世。为了实现这些目标，将在先前从 EEP 收集的两个高积累率沉积岩芯中测量一套综合的多个代理。这些指标包括：自生铀作为底层水氧合的指标，底栖有孔虫的放射性碳年龄作为 EEP 深水年龄变化的指标，231Pa/230Th 比率和过量 Ba 通量作为生产力指标，过量 230Th-导出 232Th 通量作为灰尘通量的代表，浮游有孔虫中的 B/Ca 比率作为碳酸根离子的代表地表水浓度以及 Nd 和 Pb 同位素比作为沉积物碎屑成分尘埃来源的代理，因此也是热带辐合带迁移的指标。通过调查末次冰河期寒冷时期（即约 71,000 至 14,000 年前）深海中呼吸碳库的储存情况，同时探讨这种储存与出口产量和潜在铁施肥变化的关系，该研究将揭示海洋（分层/通风）和大气（风带转移）环流之间的机制联系以及大气二氧化碳水平的改变。该奖项反映了通过使用基金会的智力价值和更广泛的影响审查标准进行评估，NSF 的法定使命被认为值得支持。