Bedrock topography requirements for reducing uncertainties in ice sheet model projections of century-scale Thwaites Glacier sea level contribution

Abstract:

Determining the future outcome of the Antarctic ice sheet is imperative for understanding and narrowing the large existing uncertainties in century-scale sea level rise (SLR) prediction. One of the most significant glaciers in this ice sheet, Thwaites Glacier, is on the brink of destabilization and is known to potentially be the largest contributor of SLR in the world. Within the cryosphere community, we often look at basal melting rates and bedrock topography being the most powerful driving forces in estimated glacial retreat. To examine the impact of bedrock topography within known error at Thwaites, we examine the glacier's dynamics in the Ice-Sheet and Sea-level System Model (ISSM) with an average bedrock of x̄ and a net sampling region within ±3σ. We find that within these bounds a complete destabilization vs near stability is possible in the glacier. Using the ISSM-DAKOTA uncertainty quantification framework , we then perform an uncertainty quantification experiment of the extent of topographic variability affecting the estimated 200 year SLR due solely to Thwaites. We succeed with a wavelet decomposition on the bedrock topography map and amplify the high frequency filter to perturb our system with realistic noise and proceed to identify candidates for minimum spatial and vertical topographic resolutions required for reduced and acceptable uncertainties in scientific modeling of Thwaites.