Extreme Antarctic Sea Ice Loss Facilitated by Negative Shift of Southern Annular Mode

Antarctic sea ice area exhibited an abrupt decline in 2015–2016, transitioning from a near record maximum state to a then-record minimum state. The underlying drivers are still being studied, raising questions whether this marks the onset of a long-term decline, or an isolated internal climate variability event. We identify extreme events in CMIP6 pre-industrial control simulations that are comparable to the observed extreme event in 2015–2016 and explore their atmospheric and oceanic drivers. Results show these events are rare but possible. The most robust association we find is between a negative Southern Annular Mode transition and extreme Antarctic sea ice loss. Most models show sea ice recovery after extreme loss, differing from the persistent decline observed in recent years. This contrast suggests anthropogenic forcing may now be playing a role. Our results underscore the role of internal variability while improving understanding of extreme events and their relevance for future sea ice predictability.