CAREER: Deconvolution of marine oxygen isotopic variability with an Earth system model to constrain sea level across the Pliocene

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The project aims to constrain sea level during the Pliocene Epoch (5.3 – 2.6 million years ago) in an effort to better understand ice sheet stability. With carbon dioxide concentration similar to present-day and global temperatures 2-4°C warmer than preindustrial, the Pliocene provides a good analog for future climate change.

Sea level was likely higher during the Pliocene, but significant uncertainty remains, with estimates ranging from 0 to 50 meters above present-day. To refine Pliocene sea level estimates, this study uses a series of Earth system model simulations to reinterpret records of past temperature and ice volume. The Earth system model data from this project will go into a public database, providing a community resource for education and future research.

This project will also produce a collection of educational activities for high school, undergraduate, and graduate students to foster the next generation of geoscientists.

Marine oxygen isotope records have been fundamental to our understanding of past climates. However, extracting ocean temperature, circulation, and sea level from marine oxygen isotope records remains difficult. Earth system models that track water isotopologues can quantify the contributions from ocean isotopic composition and temperature to the marine oxygen isotope records, and therefore, can provide estimates of past sea level.

This project will leverage an Earth system model that tracks water isotopologues to explore marine oxygen isotope responses to a suite of orbital, carbon dioxide, and ice sheet configurations of the Pliocene. These simulations will 1) allow for the construction of a Pliocene climate emulator capable of producing transient global reconstructions of isotopic changes of the ocean, atmosphere, and land, 2) provide forcings for dynamic ice sheet simulations, which will serve as an independent and complementary assessment of past sea level and oxygen isotope variability, and 3) evaluate the skill and sensitivity of the extensive Pliocene proxy network.

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.