Role of anthropogenic forcing in Antarctic sea ice variability simulated in climate models.

Antarctic sea ice extent has seen a slight increase over recent decades, yet since 2016, it has undergone a sharp decline, reaching record lows. While the precise impact of anthropogenic forcing remains uncertain, natural fluctuations have been shown to be important for this variability. Our study employs a series of coupled model experiments, revealing that with constant anthropogenic forcing, the primary driver of interannual sea ice variability lies in deep convection within the Southern Ocean, although it is model dependent. However, as anthropogenic forcing increases, the influence of deep convection weakens, and the Southern Annular Mode, an atmospheric intrinsic variability, plays a more significant role in the sea ice fluctuations owing to the shift from a zonal wavenumber-three pattern observed in the historical period. These model results indicate that surface air-sea interaction will play a more prominent role in Antarctic sea ice variability in the future.