The Arctic Ocean in CMIP6 Models: Biases and Projected Changes in Temperature and Salinity

We examine the historical evolution and projected changes in hydrography of deep basin Arctic Ocean 23 climate models participating Coupled Model Intercomparison Project Phase 6 (CMIP6). The comparison between simulations observational climatology shows that simulated Atlantic Water (AW) layer is too thick majority models, including multi-model mean (MMM). Moreover, halocline fresh MMM. Overall our findings indicate there no obvious improvement representation CMIP6 compared to CMIP5. change projections reveal sub-Arctic seas are outstanding warming hotspots, causing a strong trend AW layer. MMM temperature increase averaged over upper 700 m at end 21st century about 40% 60% higher than global SSP245 SSP585 scenarios, respectively. Salinity few hundred meters decrease However, spread salinity large tendency toward stronger not by all models. identified biases projection uncertainties call for concerted effort major improvements coupled