Unprecedented 2024 East Antarctic winter heatwave driven by polar vortex weakening and amplified by anthropogenic warming

Abstract During July–August 2024, East Antarctica experienced the most intense winter heatwave in the 46-year satellite era, with regional mean surface air temperatures across Dronning Maud Land exceeding the climatological mean by more than 9°C for 17 consecutive days. To explore the physical drivers and quantify the anthropogenic contribution to this unprecedented event, we propose a multi-model, multi-method attribution framework integrating regional climate model-based storyline attribution, circulation analogues, and large-ensemble probabilistic attribution. The results show that a pronounced weakening of the stratospheric polar vortex initiated a quasi-barotropic high-pressure anomaly, which enhanced meridional heat and moisture transport and accounted for approximately 50% of the observed surface warming. Across different models and attribution methods, synthesis of the attribution results indicates that anthropogenic warming intensified the event by approximately 0.7°C and more than doubled the likelihood of such exceptional winter heatwaves in the current climate. Probabilistic attribution further indicates that, compared to a natural climate without human influence, the likelihood of such events increases from 2–3 times today to ~6 times under moderate emissions and up to 26 times under high emissions by 2100. These findings reveal how human-induced warming is transforming even the coldest regions, with implications for ice shelf stability and predictability of future Antarctic extremes.