Antarctic temperatures soar 50 degrees above norm in long-lasting heat wave

This historic warm spell in East Antarctica is an ominous example of the temperature spikes this polar climate could experience more of in a warming world.

Ground temperatures in East Antarctica have soared more than 50 degrees (28 Celsius) above normal in the second major heat wave to afflict the region in the past two years. This historic warm spell could persist for another 10 days and is an ominous example of the major temperature spikes this polar climate could experience more frequently in a warming world.

“This heat wave is a near-record (or record) event for the region of Antarctica it’s having the biggest impact on,” Edward Blanchard, an atmospheric scientist at the University of Washington, said in an email. “The heat wave’s large footprint is also remarkable,” as it covers a large section of East Antarctica, which makes up most of the continent.

What is causing the heat wave?

Winter temperatures in Antarctica substantially fluctuate because of the lack of sunlight, but this heat wave is a much larger deviation from the norm than usual. It’s too early to determine all of its causes, but scientists say it may be at least partially linked to processes occurring 20 miles (30 kilometers) above the surface in the stratosphere.

The stratosphere contains a strong band of cold air and low pressure spinning around each pole, known as the polar vortex. The vortex is typically strong and stable during winter in the southern hemisphere, said Amy Butler, an atmospheric scientist at the National Oceanic and Atmospheric Administration. But this year, she said, it’s been jostled by atmospheric waves, weakening the vortex and causing high-altitude temperatures to soar; this is known as a sudden stratospheric warming event.

“The main reason it is notable is because it is usually a relatively quiet time of year for the Southern Hemisphere polar vortex,” Butler said. This event has lead to some record temperatures high in the stratosphere.

Data shows that the sudden stratospheric warming event is also affecting the lower atmosphere where weather occurs. The warming has weakened the belt of westerly winds around Antarctica, commonly referred to as the jet stream. This has allowed frigid air normally confined near the South Pole to veer north toward New Zealand, southern Africa and southern South America, like a refrigerator door left ajar. As the deep chill has escaped East Antarctica, temperatures have dramatically risen there in response.

Atmospheric pressures over East Antarctica are also surging to “absolutely bonkers” levels, tweeted Ben Noll, a meteorologist based in New Zealand. “The weather in the Southern Hemisphere is a little wild at the moment!” he wrote.

“With global temperatures increasing, that raises the potential ‘baseline’ for the average temperatures,” said David Mikolajczyk, a research meteorologist at the University of Wisconsin-Madison. As a result, “strong warming events such as this one can occur more frequently and have a bigger impact.”

The largest heat wave in Antarctica — and anywhere in the world — occurred in March 2022, when the eastern coast of Antarctica spiked at least 70 degrees (39 Celsius) above normal. Scientists on-site wore shorts and removed their shirts, while the area experienced intense melting.

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