Paleobiogeochemistry of marine sediments

海底的沉积物是过去气候和海洋变异性的自然档案。我建议通过测定各种有机遗骸的含量以及矿物和化学性质，即所谓的替代物，来解开这些记录中保存的信息。我对古海洋学研究的新贡献的关键是一种多代理方法，使用了广泛的代理，使我的团队能够区分本地和全球气候信号，并建立气候系统不同组成部分之间的阶段性(即因果)关系。 我的团队的研究有两个主要的长期目标：更充分地了解热带太平洋在过去全球气候变化中的重要性，以及建立对氮的彻底理解 海洋氮素清单过去变化的同位素证据。赤道太平洋是 地球气候系统，一直被认为是过去全球气候的煽动者、放大者和调解者 年际时间尺度到几千年时间尺度的变化。例如，厄尔尼诺南方涛动(ENSO) 主导着今天热带太平洋的年际变化，遥相关影响着气候 世界范围内，因此有人提出过去的全球气候变化可能受到 热带太平洋平均状态的“类ENSO”变化。我的跨学科研究 对海洋氮循环和清单过去变化的氮同位素证据进行系统分析，将有助于阐明诸如硝酸盐循环等生物地球化学变化是否是海洋对大气中二氧化碳在数千年时间尺度上的封存变化的主要原因这一重要问题。 对海洋和大气的空间和时间变异性以及地球气候系统各组成部分之间的相互关系进行这种多代理重建，对于验证当前的气候模型和建立一个必须衡量潜在人为影响的“背景”状态是必要的。

The sediments on the sea floor are natural archives of past climate and ocean variability. I propose to unravel the information preserved in these records by determining the contents of various organic remains and mineral and chemical properties, so- called proxies. The key to my novel contributions to paleo-oceanographic research is a multi-proxy approach, using a wide range of proxies, which enables my group to differentiate between local and global climate signals, and to establish phasing (i.e. causal) relationships between different components of the climate system. Research in my group has two primary long-term goals: to understand more fully the importance of the tropical Pacific Ocean in past global climate change, and to establish a thorough understanding of nitrogen isotope evidence for past changes in the oceanic nitrogen inventory. The equatorial Pacific is fundamental to Earth's climate system, and has been purported to be instigator, amplifier and mediator of past global climate change on inter-annual to multi-millennial time-scales. For example, the El Niño Southern Oscillation (ENSO) dominates the inter-annual variability of the tropical Pacific today, with tele-connections affecting climate worldwide, and it has thus been proposed that past global climate change could have been modulated by "ENSO-like" variations in the mean state of the tropical Pacific. My cross-disciplinary research into the systematics of nitrogen isotope evidence for past changes in the oceanic N cycling and inventory will shed light on the over-arching question whether or not biogeochemical changes, such as nitrate cycling are the primary cause for changes in the oceanic sequestration of atmospheric CO2 on multi-millennial time-scales. This kind of multi-proxy reconstruction of the full range of the spatial and temporal variability of the ocean and atmosphere and the interrelation between various components of Earth's climate system is required for validating current climate models and for establishing a 'background' state against which potential anthropogenic influences will have to be measured.