Heatwave in Antarctica? Temperatures soar 20°C above normal alarming scientists

Parts of Antarctica have recorded winter temperatures as much as 20°C above the seasonal average, in an episode that has broken long-standing records and led to snow and ice melting during what is usually the harshest phase of the Antarctic winter. The unusual warmth has raised fresh concern among researchers about the pace of climate change in one of the coldest and most remote parts of the world.

The Antarctic Peninsula has been at the centre of the event, with scientists reporting a prolonged heatwave, temperatures above freezing for nearly three weeks, melting on the ground and exceptionally low winter sea ice in nearby waters. Researchers said the episode reflects both immediate weather conditions and a longer-term warming trend that has become more evident in recent decades.

Record-breaking winter

The highest reading was recorded at Argentina’s Esperanza research station on the Antarctic Peninsula, where the temperature reached 15.4°C on June 6. This broke the site’s previous winter record by about 2°C and was roughly 20°C higher than what is normally expected at this time of year.

Researchers said what was especially striking was that this was not a brief spike. Daily maximum temperatures on the Antarctic Peninsula stayed above the freezing point for nearly three weeks, an extraordinary development during winter in the southern hemisphere. Climate scientist Raúl Cordero of the University of Groningen described the event as “absolutely crazy” and said the 20°C departure from normal was “a huge anomaly”.

Ice melting during the winter

The effects of the warmth have already been seen on the ground. On King George Island, researchers reported that areas usually covered by snow and ice had turned brown, grey and green in places as thawing exposed bare earth. Temperatures there rose to 4.6°C, leading to widespread melting.

Chilean glaciologists working in the region said they also encountered rain falling on glaciers, which is highly unusual for this time of year. According to researchers, glaciers that would normally be building up snow during winter instead underwent surface melting, a process known as ablation.

What drove the heatwave

Scientists have attributed the heatwave mainly to strong northerly winds that carried unusually warm air deep into the Antarctic Peninsula. They said weather systems can produce short warm spells naturally, but added that the strength and duration of such events are becoming more common in a warming world.

Researchers noted that similar extreme heatwaves in Antarctica have occurred more often since the 1980s, a pattern they said is consistent with wider evidence of human-driven climate change. The Antarctic Peninsula is already regarded as one of the fastest-warming regions on the planet and has warmed significantly over the past several decades.

Sea ice loss and climate impact

The heatwave has also coincided with exceptionally low levels of winter sea ice in parts of Antarctica. Scientists estimated that the Bellingshausen Sea, to the west of the Antarctic Peninsula, is missing an area of sea ice roughly equal to the size of France.

Sea ice helps keep regional temperatures low by reflecting sunlight. When it is lost, darker ocean waters absorb more heat, which can intensify warming and create a feedback loop that leads to further ice loss. Experts said the lack of sea ice may have strengthened the recent heatwave by weakening this cooling effect.

Scientists said a single heatwave is unlikely to trigger a dramatic rise in global sea levels, but warned that repeated events of this kind point to a broader trend. Antarctica contains enough ice to significantly reshape coastlines worldwide if major glaciers become unstable.

Possible fallout

The Thwaites and Pine Island glaciers, both closely watched by scientists, are considered especially vulnerable. Continued warming and reduced sea ice could weaken the floating ice shelves that help hold them back, potentially allowing more ice to move into the ocean.

The impact is not limited to sea levels. Shrinking sea ice can also disrupt Antarctic ecosystems by affecting krill, which form a key part of the Southern Ocean food chain. This can have knock-on effects for penguins, seals and whales. Scientists have already linked recent declines in sea ice to breeding failures in emperor penguin colonies.

For decades, Antarctica was seen as one of the last great wildernesses, shielded from many of the rapid changes affecting other parts of the Earth. The latest winter heat records, the melting seen on the ground and the loss of sea ice suggest that even this remote continent is being affected by a warming climate.