Collaborative Research: Using the Ice Sheet and Sea-level System Model and geological constraints to investigate the disappearance of the Laurentide Ice Sheet

Estimates of the magnitude of sea-level rise largely come from computer models that predict ice-sheet behavior. For these models to accurately predict sea-level rise, physical ice-sheet processes must be properly represented. Accurate predictions of ice-sheet behavior and the magnitude of sea-level rise are critical for decision makers. This project will simulate the complete disappearance of the Laurentide Ice Sheet that once covered much of North America. The retreat of the Laurentide Ice Sheet that began about 20,000 years ago presents a natural test case to better understand 1) the physical driving mechanisms that result in the complete disappearance of an ice sheet, and 2) the rate at which an ice sheet disappears. Lessons learned from this research will provide key insights into how large-scale ice-sheet retreat occurs which has clear relevance for predicting the future evolution of Earth’s vulnerable extant ice masses, such as the Greenland and West Antarctic ice sheets.A key question in ice-sheet science is determining how the influence of dynamic mass loss changes through time for a retreating ice sheet and what might control this variability. Lessons from prior episodes of ice-sheet retreat in the geologic record can elucidate how the role of dynamic mass loss changes with time in a fluctuating climate and improve ice-sheet model performance. The researchers will use the next-generation state-of-the-art Ice Sheet System and Sea-level Model (ISSM) to explore the disappearance of the Laurentide Ice Sheet over the last 20,000+ years. In a first-of-its-kind application, ISSM will be used at a spatial resolution capable of capturing large-scale ice-streaming and ice discharge through narrow fjords, along with implementation of coupled solid-Earth-sea-level feedbacks to investigate the role of dynamic ice discharge in driving the disappearance of the Laurentide Ice Sheet. To test model performance, the researchers will compare simulations of Laurentide Ice Sheet retreat against both existing and new geologic benchmarks generated over the course of this project. This project will provide the first quantitative estimates of how the percentage of dynamic mass loss versus surface mass balance evolved over the course of a full deglacial sequence and how this evolution influenced the fate of the Laurentide Ice Sheet. The project will develop a new collaboration with California State University, Long Beach, which is a designated minority serving institution, to recruit students from the Los Angeles area for internships at NASA’s Jet Propulsion Laboratory by leveraging an existing program.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.