Historical and Projected Antarctic Sea Ice Trends Across High‐Resolution Coupled Model Hierarchies

Coupled climate models generally simulate a decline in Antarctic sea ice extent (SIE) over the satellite period, failing to capture the observed near‐zero trend. Recent work has suggested that high‐resolution ocean models could ameliorate this issue via improved representation of mesoscale ocean processes, which may delay simulated Antarctic SIE decline. We investigate this hypothesis using two high‐resolution hierarchies of coupled climate models developed at GFDL and NCAR, which span atmospheric resolutions of 0.25–1 and ice‐ocean resolutions of 0.1–1, as well as three generations of Coupled Model Intercomparison Project (CMIP) models. Across the high‐resolution hierarchies and CMIP ensembles, we find no clear relationship between ocean and atmospheric resolution and Antarctic SIE trends over both the satellite period and the remainder of the 21st century. Climate models that reproduce observed trends in individual ensemble members are those that exhibit large amplitude multi‐decadal Southern Ocean climate variability.