by Richard Levy, Molly O. Patterson, Tina van de Flierdt, Timothy Naish

Response of the West Antarctic Ice Sheet (WAIS) to projected warming remains a significant uncertainty in sea level rise projections. This project will focus on understanding past and current drivers, mechanisms and feedbacks that influence retreat of ice sheets, to reduce uncertainty in numerical model projections of future changes. The SWAIS 2C Project will address the overarching question: How will marine-based ice sheets respond to a 2°C increase in global temperature and what are the local, regional, and global environmental consequences of this response if temperatures ultimately exceed this 2°C increase? We have established an international team of geologists, glaciologists, geophysicists, and ice sheet and climate modelers who will use a proven ‘trident’ approach that integrates studies of past and present ice sheet behavior to inform future projections (using models) of WAIS response to climate change. Geological records provide the past (via past behavior, system boundaries, processes, and rates of change), where modern observational data provide details of the variables and complexities (processes and changes), and models can play future scenarios to equilibrium states in accelerated time. We will recover and study sedimentary records of past environmental change and ice sheet dynamics in the interior Ross Sea Embayment of West Antarctica, targeting past warm intervals when global mean temperatures were similar to those projected for the coming decades. We will examine present-day ice sheet dynamics through detailed study of glacial and oceanographic processes within the Ross Ice Shelf cavity and at the grounding zone near Kamb Ice Stream. New knowledge regarding ice flow dynamics, grounding line interactions and the influence of oceanic and atmospheric warming will be integrated into numerical models to improve and enhance simulations of ice mass change under future climate scenarios. This integrated 3-fold approach will improve projections of Antarctic ice sheet contribution to global sea level. We will utilize new drilling technology to obtain a sedimentary history of past ice sheet dynamics at two locations (Kamb Ice Stream and Crary Ice Rise) along the Siple Coast in the West Antarctic interior. Geological records from this location have proven difficult to obtain but are critical to better constrain marine ice sheet sensitivity to past and future increases in global mean temperature up to 2°C. Technological advances developed in this project will enable us to test whether WAIS collapsed during past intervals of warmth and determine its sensitivity to a +2°C global warming threshold

• We have five scientific objectives with associated testable hypotheses: O1: Glacial dynamics since the Last Glacial Maximum to provide mechanistic insights; O2. Late Quaternary sea level and ice sheet contribution in response to near-future climates; O3. Pliocene ice sheet variability (current CO2 forcing and >2°C warming); O4. Late Oligocene – Miocene variability and the role of tectonics and carbon cycle feedbacks; O5. Life beneath the surface – microbial communities in extreme polar environments;

Antarctica, Glacial Isostatic Adjustment, Ice Sheet, Melt Water, Sea Level

Latitude: -82.6289, Longitude: -156.305