Right now it is winter in Antarctica, the season when sea ice spreads rapidly around the continent and builds towards its September peak. Yet satellite images this year have revealed something startling. The Bellingshausen Sea, which sits on the western side of the Antarctic peninsula and is normally locked under ice by June, is almost entirely ice free.
How much ice has vanished
Compared with the average recorded between 1991 and 2020, scientists say the region is short of roughly 650,000 square kilometers (250,000 square miles) of sea ice. That is an expanse about the size of all of France, and nearly ten times the size of Tasmania.
Across the whole continent the picture is similar. On June 10 there was about 11.4 million square kilometers of sea ice ringing Antarctica, against a long-term average for that date of 12.6 million square kilometers.
"It's done"
Dr Will Hobbs, an Antarctic sea ice expert at the University of Tasmania working with the Australian Antarctic Program Partnership, did not hide his alarm.
"I'm concerned. It's depressing," he said. "It is remarkable that we are in June, and there is no sea ice there."
Hobbs pointed out that this is the third time in four years that sea ice in the region has been very low. "I don't think we will see sea ice there any more. It's done," he said. In his view the loss is probably tied to changes in the ocean, and researchers are now working to figure out whether global heating is a factor as well.
What it means for krill and marine life
Hobbs stressed that the area matters greatly for krill, a critical link in the food web for the species that live there. In winter, krill would normally shelter from predators beneath the ice, grazing on algae as they go.
Glaciers and the threat to sea levels
Dr. Phil Reid, who monitors Antarctic conditions at Australia's Bureau of Meteorology, said the Bellingshausen Sea had recently seen "incredible coastal exposure" in both winter and summer.
He noted that just to the west of this area lie the Pine Island and Thwaites glaciers, the continent's biggest contributors to ice loss and rising sea levels. If protective sea ice is missing for longer stretches, Reid warned, the floating ice shelves in front of those glaciers could break up faster. That, in turn, could accelerate the loss of ice from the glaciers and push global sea levels higher in the years ahead.
A crisis for penguins
The coastline of the Bellingshausen Sea was the scene of tragedy in late 2022, when thousands of emperor penguin chicks died during a "catastrophic breeding failure" across four colonies. That episode helped persuade UN advisers earlier this year to move the species up two categories to "endangered" on the international threatened species list.
Dr. Peter Fretwell, a scientist at the British Antarctic Survey who has been documenting the penguin's decline, said the current loss of sea ice in the region was "a serious problem for penguins, especially emperors."
"Sea ice is forming too late and breaking up too early. It leads to reduced breeding success and longer trips to molting grounds."
Fretwell added that Adelie penguin numbers are also falling, and that crabeater seals are being pushed to migrate in summer in search of stable ice.
Linking the heat to the missing ice
This month the Antarctic peninsula endured an extreme temperature spike that ran over several days. While "nobody has done the numbers," Hobbs said, it is reasonable to suggest the heat wave was "made worse by the lack of sea ice." Normally, he explained, sea ice helps cool any warmer airflow drifting into the region from the north.
Officials at Argentina's national weather service, Servicio Meteorológico Nacional, said the country's Esperanza base, on the northeastern tip of the peninsula, had recorded an "extreme temperature event" that peaked on June 5 and 6. Maximum temperatures of 15.4 degrees Celsius and 13.4 degrees Celsius were logged on those days, at a time when average daily maximums sit at minus 6.2 degrees Celsius. The base's previous June record of 13.3 degrees Celsius had stood since June 12, 1998. The peninsula's daytime temperatures last week climbed as high as 15.4 degrees Celsius, more than 20 degrees Celsius above average.
