Collaborative Research: EAR Climate - Pairing calcium and clumped isotopes to inform carbon cycle and climate dynamics at the onset of the Late Paleozoic Ice Age

过去的气候与了解地球系统对二氧化碳等温室气体水平上升的敏感程度有关。3.5亿至2.9亿年前的晚古生代冰期是过去5亿年中最长的冰期，也是研究地球气候与全球碳循环耦合关系的重要机会。虽然深度时间研究的挑战在于需要依靠气候的“代理”而不是直接测量，但最近的进展为了解气候系统中影响我们未来的全部自然变率提供了新的机会。该项目将开发新的同位素代用物，以了解晚古生代冰期开始时陆地植物进化对有机碳埋藏、大气二氧化碳和温度的作用。收益将包括培训早期职业科学家，包括那些来自代表性不足的群体的科学家，以及发展实践演示，旨在提高学生对地球大气中碳输入和碳输出之间微妙平衡的理解。关于晚古生代冰期的拟议研究将探讨阻碍理解全球碳循环与气候之间关系的重要问题：1)成岩作用对浅水碳酸盐中稳定碳同位素的影响，这些碳同位素被用作碳循环的代理；2)海洋氧同位素记录中温度与冰体积的作用。为了验证成岩作用对全球碳循环和温度对冰体积的影响，本研究将利用新的钙和块状同位素系统。钙元素的优势在于可以深入了解成岩作用对碳同位素测量的影响，而团块同位素记录温度，但不受矿物学、降水速率或海水同位素演化的影响。钙和块状同位素可能会改变我们对地球历史的理解，这项研究将有利于在一系列空间和时间尺度上的研究方法。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Past climates are relevant to understanding how sensitive the Earth system is to rising greenhouse gas levels like carbon dioxide. The Late Paleozoic Ice Age from 350 to 290 million years ago was the longest-lived glaciated period of the past half-billion years and represents an important opportunity to study the coupling between Earth’s climate and the global carbon cycle. Although the challenge in deep time studies is the need to rely on ‘proxies’ for climate rather than direct measurements, recent advances provide new opportunities to understand the full range of natural variability in the climate system that informs our future. This project will develop novel isotope proxies to understand the role of land plant evolution on organic carbon burial, atmospheric carbon dioxide, and temperature at the beginning of the Late Paleozoic Ice Age. Benefits will include training of early career scientists, including those from under-represented groups, and developing hands-on demonstrations aimed at improving student understanding of the delicate balance between carbon inputs and outputs to Earth’s atmosphere. The proposed research on the Late Paleozoic Ice Age will investigate important questions that have hindered progress towards understanding the relationship between global carbon cycling and climate: 1) diagenetic influences on stable carbon isotopes in shallow water carbonates that are used as a proxy for carbon cycling and 2) the role of temperature versus ice volume in marine oxygen isotope records. To test hypotheses of diagenesis versus global carbon cycling and temperature versus ice volume, this research will utilize the novel calcium and clumped isotope systems. Calcium has the advantage of providing insight on the impact of diagenesis on measured carbon isotopes whereas clumped isotopes record temperature but are unaffected by mineralogy, precipitation rate, or the isotopic evolution of seawater. Calcium and clumped isotopes may transform our understanding of Earth history and this study will benefit research approaches over a range of spatial and temporal scales.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.