Arctic Ocean Freshwater Storage and Export in CMIP6 Models

Over the past few decades the Arctic has experienced substantial changes in sea ice cover and the hydrologic cycle, both of which strongly impact the freshwater storage in, and export from, the Arctic Ocean. The fate of Arctic Ocean freshwater (FW) is of global relevance, as it can impact deep water formation in the North Atlantic and potentially the strength of the Meridional Overturning Circulation. Despite its importance, the projected changes in the Arctic FW budget vary between models. Here we analyze the newest generation of climate models from the Coupled Model Intercomparison Project phase 6 (CMIP6), to assess their agreement on projected Arctic FW budget changes, as well as compare these models against observations for the historical period. Particular attention will be paid to improvements in the CMIP6 models relative to their CMIP5 counterparts (if applicable), including, but not limited to, the impact of model resolution, bathymetry, and the existence of passages through the Canadian Arctic Archipelago (e.g., Nares Strait, Barrow Strait/Lancaster Sound) on the simulated Arctic FW budget. Furthermore, we will assess when forced trends in each component of the freshwater budget are statistically distinguishable from natural climate variability across the models.