CAREER: Evaluating controls on marine-terminating outlet glacier stability in Southwest Alaska

Sections of ice sheets that flow into the ocean are important contributors to global sea-level rise, yet scientists still do not fully understand why some of these glaciers retreat gradually while others retreat quickly. This project will investigate how an ice sheet that once covered Southwest Alaska responded to major environmental changes at the end of the last ice age, providing an opportunity to study fundamental ice sheet processes that cannot be directly observed in the modern era. Results from this research will help evaluate models used to forecast future sea-level change, supporting infrastructure planning for America’s coastal communities, ports, and shipping corridors. The project will also prepare Queens College students for STEM careers through a course-based undergraduate research experience in glacial geology, a field-based science communication course, and a tiered mentoring program. Public outreach will be conducted in partnership with the Queens Public Library, where the project team will lead free science workshops for youth in grades 4-12. Marine-terminating outlet glaciers transfer large volumes of ice from ice sheet interiors to the ocean and are capable of switching from slow retreat to rapid collapse. Understanding what controls these different behaviors is essential for improving projections of ice sheet and sea-level change, but satellite observations capture only a small fraction of the conditions that outlet glaciers have experienced through time. This project will address that limitation by investigating the retreat of the Cordilleran Ice Sheet in Southwest Alaska, which was strikingly similar to parts of Greenland and Antarctica today. Using geologic mapping, cosmogenic nuclide surface exposure dating, and ice sheet modeling, the research will determine whether outlet glaciers draining to the North Pacific retreated before those in the North Atlantic during the Last Deglaciation (~22,000-11,000 years ago) and evaluate how ocean and atmosphere conditions, topography, and ice dynamics interact to influence the transitions between gradual and rapid ice retreat. Results from this project will provide new insight into the processes that control outlet glacier stability and improve understanding of how the Arctic responded to past environmental change. Educational activities will engage Queens College students in all aspects of the scientific process, allowing students to emerge from this project well-prepared to join the U.S. STEM workforce. 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.