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

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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.