‘Astonishing’ Antarctica heat wave sends temperatures 50 degrees above normal

CNN – A record-breaking heat wave unfolding at what should be the coldest time in Earth’s coldest place has scientists concerned about what it could mean for the future health of the Antarctic continent, and the consequences it could inflict for millions of people across the globe.

Temperatures since mid-July have climbed up to 50 degrees Fahrenheit above normal over parts of Antarctica and unseasonable warmth could continue through the first half of August.

The latest data shows high temperatures in portions of East Antarctica – where the most abnormal conditions are ongoing – that are typically between minus 58 and minus 76 degrees Fahrenheit are now closer to minus 13 to minus 22 degrees Fahrenheit.

That’s cold, but Bismarck, North Dakota, has reached minus 20 degrees at least once a year in almost every year since 1875. Antarctica’s typical winter cold should be operating at a level unfathomable to most people in the US.

Summerlike heat in the dead of winter – even if much of the continent is still below freezing – is an alarming development for a place more capable than any other of generating catastrophic sea level rise as fossil fuel pollution continues to drive global temperatures upward.

Most of the planet’s ice is stored here, and were it all to melt, would raise average global sea levels by well over 150 feet. Even smaller icy features, like the so-called Doomsday Glacier, could raise sea levels by 10 feet if they were to melt – catastrophic amounts for the world’s coastal communities.

It’s possible more heat waves like this will happen in future winters, which could leave the icy continent less fortified for its hottest season – summer – and more vulnerable to melting during subsequent heat waves, said David Mikolajczyk, a research meteorologist with the Antarctic Meteorological Research and Data Center at the University of Wisconsin-Madison.

Increased Antarctic melting could also potentially alter global oceanic circulations, Mikolajczyk told CNN. These circulations play an outsized role in making the planet’s climate habitable.

“I’m sure more (impacts) will emerge with time as we understand (this heat wave) better, but at the moment, it’s just a case of astonishment really, what we’re seeing,” Thomas Bracegirdle, deputy science leader for the British Antarctic Survey’s Atmosphere, Ice and Climate team, said.

Bracegirdle told CNN the temperatures in this event were record-breaking and were an important signal of what could be coming in the longer term. Heat waves of this magnitude should be quite rare in Antarctica and scientists aren’t yet certain that they are occurring more frequently, but that may be changing.

“All we can say at this stage is that more high temperature extremes are what we expect (in Antarctica) under a changing climate, but for this particular event we’ll have to study more,” Bracegirdle said.

It also contributed significantly to Earth’s new hottest day on record in late June, according to an analysis from the European Union’s Copernicus Climate Change Service.

This is the second significant heat wave Antarctica has endured in the last two years. During the previous in March 2022, temperatures in some locations reached up to 70 degrees above normal, the most extreme temperature departures ever recorded in this part of the planet.

That unprecedented heat wave was made worse by climate change, according to a 2023 study published in Geophysical Research Letters. Climate change contributed 3.6 degrees of warming to the heat wave and could worsen similar heat waves by 9 to 10.8 degrees Fahrenheit by 2100, the study found.

While the current heat wave hasn’t seen temperature departures reach the level of 2022, it’s been much more expansive and long-lasting, according to Ted Scambos, a glaciologist at the University of Colorado Boulder.

And the crucial differences between the two come down to what’s happening in the atmosphere.

‘A very unusual event’

The set of atmospheric conditions largely responsible for the ongoing heat wave – a breakdown of the southern polar vortex – is only expected to occur once every two decades on average, according to Bracegirdle.

“This is a very unusual event, from that perspective,” Bracegirdle added.

Just like the Northern Hemisphere, the Southern Hemisphere has a polar vortex – strong winds circulating high in the atmosphere that trap cold air in place.

But when the southern polar vortex gets disrupted, it releases cold air trapped over Antarctica and sends bursts of it farther north. This also leaves the door open for air to rush down from the upper atmosphere, warming along the way.

The southern polar vortex is disrupted much less frequently than its northern counterpart, which explains why such heat waves are much less frequent, according to Amy Butler, a research physicist at NOAA’s Chemical Sciences Laboratory.