Unprecedented Winter Heatwave over East Antarctica in 2024

In austral mid-winter 2024, East Antarctica experienced an unprecedented heatwave with an estimated return period of approximately 1-in-130 years. Temperatures in parts of East Antarctica soared nearly 20°C above the climate norm, making it the most extreme heatwave ever recorded in the region. This record-breaking event was primarily driven by the weakening of the polar vortex, which trapped heat over the region and prolonged the warming. Here, we present initial findings from the first multi-method attribution study of this East Antarctic heatwave: pulling together the circulation analog method, statistical attribution analysis (leveraging multiple global model simulations and large-ensemble atmospheric model simulations), and a storyline approach using a set of pseudo-global warming regional climate simulations dedicated for this event.

Attribution based on the circulation analog method reveals that changes in the dynamical flow explain a fraction of more than 60% of increases in the probability of heatwaves. Furthermore, statistical attribution method indicates that such an event would have been potentially impossible without human-induced warming. The storyline approach demonstrates that background warming due to greenhouse gas emissions has significantly intensified the heatwave's magnitude and extended its duration. Under future warming scenarios, similar heatwave events are projected to become more frequent and intense. Our study underscores the growing vulnerability of the Antarctic climate system to future heatwave events, serving as a stark warning of the potential for polar extremes to intensify under global warming.