Antarctic ice loss may switch off planet’s fridge

The region could be in the process of changing from the planet’s refrigerator to the its radiator, climate scientists warn.

A new paper has documented what appear to be a range of extreme events in the Antarctic. Picture: Supplied

The Antarctic could be in the process of changing from being the planet’s refrigerator to the planet’s radiator, climate scientists have said after a year of record-breaking ice loss.

An area of sea ice the size of Greenland is missing on the continent, with the area covered 2.4 million sq kilometres below the 1979-2022 average.

The reduction not only means that the immediate ecosystem is affected, but it also means that the continent is less able to reflect sunlight.

“A lot of solar radiation is bounced back out into space, just reflected off the white surface,” Professor Martin Siegert, from the University of Exeter, said. When that is replaced by darker sea water, though, “that reflecting ability is reduced and the Earth absorbs that heat”.

Along with colleagues, Siegert has published a paper in the journal Frontiers in Environmental Science, documenting what appear to be a range of extreme events in the Antarctic.

These include increased calving of icebergs, loss of sea ice and massive temperature anomalies. Last year parts of East Antarctica were 40C higher than normal, after a change in air currents brought in warmer weather from Australia.

CSIRO research vessel, RV Investigator, in Antarctica. Picture: CSIRO

“It was absolutely astonishing,” Siegert said. “The largest heatwave that the Earth has ever experienced in terms of the variance from the normal.”

It meant that regions that were expected to be minus 50C were instead minus 10C.

The factors affecting Antarctic ice and climate are complex and poorly understood. In part this is because of a paucity of data. Antarctica was discovered only 200 years ago, and has been studied for far less time than other regions of the world.

When compounded with the difficulty of working there, this means that it is hard definitively to attribute changes to global warming. Until 2015, in fact, ice cover had for several years been gradually increasing.

However, scientists who have spent their careers in Antarctica say that they are experiencing repeated extremes.

Anna Hogg, of the University of Leeds, said: “As somebody who watches this happen on a day-to-day basis, I’m finding it really surprising and staggering to see the changes occur at the scale they are already.”

She said she had been especially struck by the loss of ice shelves, which form where glaciers meet the sea.

“It’s going to take decades, if not centuries, for these things to recover. There’s no quick fix to replacing this ice.”

It is winter in the Antarctic at present, and ice cover is set to keep on increasing until the end of next month. Typically, winter highs over the past 40 years – which is when satellite records began – have been 17 to 19 million sq kilometres.

During the summer low it is 2 to 4 million sq kilometres. Today’s anomaly is far outside the variability seen in either direction in previous years.

Siegert said this could not be excluded as a fluke. “It could be, because we’ve not got the scientific evidence, that it was just one of those one-in-1,000-year events, but that’s so unlikely, and I think it’s perfectly scientifically reasonable to make the assumption that it is linked to our heating planet,” he said. If so, the knock-on effect will be more heat going into the sea, he said, as is already being seen at the North Pole.

“There’s a real danger, I think, in the years coming ahead that Antarctica starts to behave in a way that looks a lot more like the Arctic, and we start to see that it stops acting as a refrigerant for the planet, and it starts acting as a radiator for the planet.”

The Times