Speaker: Alex Robel
Many marine-terminating glaciers in Greenland and Antarctica are currently retreating and thinning. In this talk, I start by describing a simple mathematical model for the response of marine-terminating glaciers to external climate forcing, which emulates changes simulated in more realistic models. Using a stochastic perturbation approach, I show that the marine ice sheet instability amplifies and skews uncertainty in projections of marine-terminating glacier change for certain vulnerable glaciers in Greenland and Antarctica. This uncertainty amplification is also present in state-of-the-art 3D simulations of marine ice sheet collapse in West Antarctica. Bumpiness of the bed can reduce this uncertainty, indicating that resolution of small-scale subglacial bed topography is critical in estimating uncertainty in future projections of sea level rise. I also show how we can interpret observations of marine-terminating glacier change by estimating the envelope of natural glacier variability expected from climate variability. I conclude by discussing the necessity of ensemble approaches to robustly estimate uncertainty in projections of future sea level rise.