Development of a Sea Ice Emulator: A Progress Update

Arctic sea ice is a complex yet fundamental component of the Earth system, and is a sensitive indicator of global climatic changes. Since the satellite record began in 1979, the Arctic ocean has received increasing attention due to the rapid decline of sea ice coverage (Niederdrenk and Notz, 2018). This has raised concerns regarding the future state of Arctic sea ice and the subsequent implications of its continued decline. Both passive satellite observations and global climate models used in the sixth phase of the Coupled Model Intercomparison Project, unanimously show continued year-round reductions in Arctic sea ice throughout the 21st century. The prediction of unprecedented Arctic sea ice loss has led to the clear consensus that the continued rate of Arctic sea ice reduction will present far-reaching, severe implications to atmospheric and oceanic systems. However, the nature and scale of the response to Arctic sea-ice loss and the mechanisms involved remains uncertain. CMIP6 models currently produce a wide spread of sea ice area projections and fail to plausibly simulate sea-ice area evolution to changes in global mean surface temperature. This limitation is exacerbated through the computational expense of current models preventing numerous runs over multi-centennial timescales and scenarios. In this PhD confirmation seminar Siân Chilcott will discuss how a sea ice emulator can be used to gain a new understanding into the behavior of complex CMIP6 models; and how such a tool will provide insight into why model projections differ from observations and what the dominant drivers of sea ice loss are. This project aims to make sense of the wide spread of CMIP6 projections in order to produce a plausible set of sea ice area projections.