Landscapes Live (16/11/2023) - Ryan Venturelli

Retreat, Recovery, and Subglacial Radiocarbon: Untangling past [in]stability of the West Antarctic Ice Sheet
Abstract: Reconstructions of past ice sheet behavior enable us to refine physical models that predict how much, how fast, and from where Antarctic ice mass loss will contribute to future sea level rise. Geological constraints on paleo ice thickness obtained from above the modern ice surface (e.g., exposure age data from deglaciated nunataks) and on paleo ice extent obtained outboard from modern margins (e.g., sediment core and geomorphic data from the ice-free continental shelf) have served as the primary tools to decipher the topology of the Antarctic Ice Sheet from the Last Glacial Maximum to present. Recent efforts to recover sediment and bedrock from beneath grounded ice in Antarctica offer insight into the southernmost extent of grounding line retreat, yielding a more complete view of ice dynamics through the last deglaciation. In this talk, I will present results from recent subglacial access efforts that have provided the first direct constraints on a less extensive West Antarctic Ice Sheet in the Holocene compared to today. These new constraints on the timing and extent of grounding line retreat prior to the modern observational record allow for a mechanistic understanding of the drivers of marine ice-sheet evolution, subglacial ecosystem processes, and subglacial Antarctica’s role in global biogeochemical cycling. I will conclude by presenting new geochemical and sampling tools under development to enable future work constraining ice-sheet history. By generating this process-to-paleo perspective on the co-evolution of cryospheric, geologic, biologic, and oceanographic systems and combining it with detailed ice-sheet modeling experiments, we can create the context required to reduce uncertainty in sea-level projections on societally relevant timescales.