In the depths of Antarctic winter—months of near‑constant darkness when temperatures normally fall well below −30°C—parts of East Antarctica warmed dramatically. During July and August 2024, some locations were as much as 28°C above the seasonal average and stayed unusually warm for more than two weeks. To illustrate the scale: an equivalent anomaly in the UK would push January conditions into the mid‑30s Celsius.
A recent study shows this was not merely an odd weather blip but a rare atmospheric disruption amplified by human‑caused climate change. It followed an extreme March 2022 episode, when several Antarctic sites briefly registered nearly 40°C above their long‑term averages—one of the largest temperature anomalies on record. Together, these events signal a shift: extreme warming is occurring in places not previously seen as vulnerable.
What happened: the event began when the Antarctic polar vortex—a high‑altitude ring of strong winds that normally traps frigid air over the continent—weakened and became distorted. The stratosphere warmed by more than 15°C in early July, with another warming surge in early August. Those stratospheric disturbances helped establish a persistent surface high‑pressure area over East Antarctica and opened a route for a long, narrow plume of warm, moisture‑rich air—an atmospheric river—to penetrate deep into the interior in midwinter, which is highly unusual.
Clouds associated with that air mass acted like an insulating blanket, trapping heat near the surface and preventing the fast cooling that normally follows a short warm spike. That kept temperatures elevated for weeks instead of hours. At the same time, Antarctic sea ice was near record low extent and the surrounding Southern Ocean was unusually warm—conditions likely related to the same large‑scale atmospheric pattern and that further supported the transport of heat into the continent.
Natural variability contributed, but climate change altered the background state. Climate model simulations comparing the present climate with a hypothetical world without human influence indicate warming has made the 2024 winter heatwave both stronger and more likely. Events of this magnitude would have been exceptionally rare in the past; under high‑emission scenarios they could become up to 20 times more frequent by the end of the century.
Why it matters: Antarctica holds most of Earth’s freshwater in massive ice sheets. Even short‑lived winter warming can affect snowfall patterns, trigger surface melt, and weaken floating ice shelves that slow the flow of inland glaciers. When ice shelves thin or collapse, glaciers can accelerate into the ocean and raise global sea level. The 2024 event highlights how climate change is altering not just average temperatures but extremes, enabling long‑standing atmospheric processes to have far larger impacts. Changes in the coldest, most remote regions can therefore have meaningful consequences for coastlines and climate systems around the world.
