Evaluating sea ice thickness simulation is critical for projecting a summer ice-free Arctic Ocean

Abstract The rapid decline of Arctic sea ice, including ice area (SIA) retreat and thinning, is a striking manifestation global climate change. Analysis 40 CMIP6 models reveals very large spread in both model simulations the September SIA thickness timing summer ice-free Ocean. existing SIA-based evaluation metrics are deficient due to observational uncertainty, prominent internal variability, indirect response forcing. Given critical roles (SIT) determining variation throughout seasonal cycle April SIT bridging winter freezing melting processes, we propose two SIT-based metrics, mean SIT, assess models’ capability reproduce historical change area. selected 11 good reduce uncertainty projected first by 70% relative poor models. chosen ensemble projects year 2049 (2043) under shared socio-economic pathways (SSP)2-4.5 (SSP5-8.5) scenario with one standard deviation inter-model 12.0 (8.9) years.