The predictive power of ice sheet models and the regional sensitivity of ice loss to basal sliding parameterisations: a case study of Pine Island and Thwaites glaciers, West Antarctica

Abstract. Ice sheet models use a wide range of sliding laws to define relationship between ice velocity and basal drag, generally comprising some combination Weertman-style power law Coulomb friction. The exact nature is not known from observational data, making assessment the suitability different difficult. question how much this choice could affect predictions future evolution an important one. Here we conduct model study large sector West Antarctic Sheet (WAIS), particularly critical component cryosphere, using parameterisations, provide sensitivity loss law. We show that, after initialisation, various result in broadly similar ranges sea level contribution over 100 years, with primarily dependent on parameter values used each Comparing mass Thwaites Pine Island glaciers neighbouring regions reveals significant qualitative geographical differences parameters modelled response changes forcing. that responses do necessarily follow universal systematic patterns, and, particular, higher exponent m imply larger rates loss. Despite magnitudes change system, all our experiments display broad similarities behaviour which serve reinforce decade-to-century-scale predictive models, regardless sliding.