In the middle of the Antarctic winter, during months of darkness when temperatures usually plunge well below −30°C, parts of the continent warmed dramatically. In July and August 2024, regions of East Antarctica experienced temperatures up to 28°C above the seasonal average and remained unusually warm for more than two weeks. To put that in context, a comparable anomaly in the UK would push January temperatures into the mid-30s Celsius.
A recent study shows this was not just an odd weather blip but a rare atmospheric disturbance amplified by human-caused climate change. It followed an extreme March 2022 event, when some Antarctic locations soared nearly 40°C above average—one of the largest temperature anomalies ever recorded. Together, these episodes signal a shift: extreme warming is no longer confined to traditionally vulnerable places.
How it happened: the winter event began with a weakening and distortion of the Antarctic polar vortex, the high-altitude band of strong winds that normally keeps cold air trapped over the continent. In early July the stratosphere warmed by more than 15°C, with another surge in early August. Those stratospheric changes helped set up a persistent surface high-pressure system over East Antarctica and opened a pathway for a long, narrow plume of warm, moisture-rich air—an atmospheric river—to penetrate deep into the interior during winter, an uncommon occurrence.
Clouds tied to the system acted like an insulating blanket, trapping heat near the surface and preventing rapid cooling, turning a brief spike into a prolonged heatwave. At the same time Antarctic sea ice was near record lows and the surrounding Southern Ocean was unusually warm, likely linked to the same large-scale conditions and helping sustain heat transport into the continent.
Natural variability played a role, but climate change altered the background state. Simulations comparing today’s climate with a world without human influence indicate that warming made the 2024 winter heatwave both stronger and more likely. Events of this magnitude would have been exceptionally rare in the past; already they are significantly more probable and, under high-emission scenarios, could become up to 20 times more frequent by century’s end.
Antarctic heatwaves matter beyond the poles. The continent holds most of Earth’s freshwater in vast ice sheets, and even short-lived warming can affect snowfall, surface melt and the stability of floating ice shelves that restrain inland glaciers. When ice shelves weaken, glaciers can accelerate into the ocean, contributing to global sea level rise. More broadly, the 2024 event shows that climate change is transforming not just average temperatures but extremes, allowing longstanding atmospheric processes to have far greater impacts in a warmer world. What happens in the coldest, most remote places has consequences for coastlines and climate patterns worldwide.
