USAP-DC

The Earth's climate has changed through time and during the Eocene Epoch (56 to 34 million years ago) there was a transition from 'greenhouse' to 'icehouse' conditions. During the Eocene, a shift to cooler temperatures at high latitudes resulted in the inception of polar glaciation. This in turn affected the environment for living organisms. This project looks to uncover the interaction between biological, oceanographic, and climate systems for the Eocene in Antarctica using chemical analysis of fossil shark teeth collected during past expeditions. The combination of paleontological and geochemical analyses will provide insight to the past ecology and ocean conditions; climate models will be applied to test the role of tectonics, greenhouse gas concentration and ocean circulation on environmental change during this time period. The study contributes to understanding the interaction of increased atmospheric carbon dioxide and ocean circulation. This project also seeks to improve diversity, equity, and inclusion within the geosciences workforce with efforts targeted to undergraduate, graduate, postdoctoral, and early career faculty.

The research goal is to elucidate the processes leading from the Eocene greenhouse to Oligocene icehouse conditions. Previous explanations for this climate shift centers on Antarctica, where tectonic configurations influenced oceanic gateways, ocean circulation reduced heat transport, and/or greenhouse gas declines prompted glaciation. The team will reconstruct watermass, current, and climate fluctuations proximal to the Antarctic Peninsula using geochemical indicators (oxygen and neodymium isotope composition) from fossil shark teeth collected from Seymour Island. The approach builds on previous shark paleontological studies, incorporates geochemical analyses for environmental reconstruction (i.e., temperature gradients and ocean circulation), and tests hypotheses on Earth System dynamics using novel global climate model simulations with geochemical tracers. This project will advance global climate modeling capabilities with experiments that consider Eocene tectonic configuration within isotope-enabled climate model simulations. A comparison of geochemical results from Eocene climate simulations and empirical records of shark teeth will reveal processes and mechanisms central to the Eocene Antarctic climatic shift.

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.

Person	Role
Kim, Sora	Investigator and contact
Scher, Howard	Investigator
Huber, Matthew	Investigator
Jahn, Alexandra	Investigator

Antarctic Earth Sciences	Award # 1842176
Antarctic Earth Sciences	Award # 1842115
Antarctic Earth Sciences	Award # 1842059
Antarctic Integrated System Science	Award # 1842059
Antarctic Earth Sciences	Award # 1842049

USAP-1842049_1

DMP_sharks_18-0621.doc

Repository	Title (link)	Format(s)	Status
Dryad	Data from: Probing the ecology and climate of the Eocene Southern Ocean with sand tiger sharks Striatolamia macrota	Not Provided	exists

1. Kim, S. L., Zeichner, S. S., Colman, A. S., Scher, H. D., Kriwet, J., Mörs, T., & Huber, M. (2020). Probing the ecology and climate of the Eocene Southern Ocean with sand tiger sharks Striatolamia macrota. Paleoceanography and Paleoclimatology, 35, e2020PA003997. (doi:10.1029/2020PA003997)
2. Kim, S. L., Zeichner, S. S., Colman, A. S., Scher, H. D., Kriwet, J., Mörs, T., & Huber, M. (2020). Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger Sharks Striatolamia macrota. Paleoceanography and Paleoclimatology, 35(12). (doi:10.1029/2020pa003997)
3. Inglis, G. N., Bragg, F., Burls, N. J., Cramwinckel, M. J., Evans, D., Foster, G. L., … Pancost, R. D. (2020). Global mean surface temperature and climate sensitivity of the early Eocene Climatic Optimum (EECO), Paleocene–Eocene Thermal Maximum (PETM), and latest Paleocene. Climate of the Past, 16(5), 1953–1968. (doi:10.5194/cp-16-1953-2020)
4. Inglis, G. N., Bragg, F., Burls, N., Evans, D., Foster, G. L., Huber, M., … Tierney, J. E. (2020). Global mean surface temperature and climate sensitivity of the EECO, PETM and latest Paleocene. (doi:10.5194/cp-2019-167)