Into the icehouse: Dramatic changes at the Devonian-Mississippian Climate Transition (DMCT)

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Reconstructions of ancient ocean temperatures give important clues to the limits of future global warming, the causes of climate change, and the impact of climate change on biodiversity. This project will test whether tropical ocean temperatures were extremely warm (35-40 °C or 95-104 °F) during the time of early animals and examine the role of rapid cooling in triggering biotic crises. The study will also explore how climate change impacted the cycling of calcium and whether linkages between the calcium and carbon cycles play a role in climate change. Proxy data for paleoenvironments will be combined with sophisticated mass balance models to further test links between calcium, carbon dioxide, and climate. The project will broaden geochemical education through (1) training of three graduate students and members of underrepresented groups in cutting-edge techniques, (2) development of exercises and independent research projects for undergraduate and graduate classes, and (3) K-12 activities at the annual TAMU Chemistry Open House. The project will enhance research and education infrastructure by supporting two cutting-edge mass-spectrometry systems and by sharing the mass balance model framework.The project will feature clumped isotope paleothermometry, a recent advance that measures the co-occurrence of 13C and 18O in carbonate molecules (e.g., Ca13C18O16O2). Analyses will be performed on well-preserved brachiopod shells from North America (US and Canada) and Eastern Europe (Russia) spanning the Late Devonian to Early Mississippian (383 to 348 million years), a time of rapid climate and ocean chemistry change (“calcite” to “aragonite” seas), and multiple biological crises. Clumped isotope measurements will be combined with measurements of calcium, carbon, and oxygen isotopes and comprehensive numerical modeling to examine the interplay between calcium, carbon, and crustal cycling during this major climatic shift in Earth’s history and foster better understanding of the consequences of climate change in our near future.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.